Gregory Maniero - Academia.edu (original) (raw)

Papers by Gregory Maniero

Springer eBooks, 2000

Lymphocyte proliferation is a prerequisite for most aspects of the mammalian acquired immune resp... more Lymphocyte proliferation is a prerequisite for most aspects of the mammalian acquired immune response. Splenic lymphocytes from golden-mantled ground squirrels collected at different phases of hibernation were stimulated in vitro with several mitogens to measure proliferative ability at several temperatures. No differences were seen in lymphocyte proliferation at any of the temperatures tested between animals at different stages of hibernation. No proliferation was detected at 5°C. T cell mitogens induced significantly higher proliferation at 37°C than at 27°C in lymphocytes from both summer and hibenrating animals. A B cell mitogen induced similar proliferation at both 27° and 37°C in cells from summer and hibernating animals. Lymphoocyte proliferation appears to be highly temperature-dependent in both summer and hibernating animals. Therefore, interbout arousals are essential for the production of a successful acquired immune response during hibernation.

Comparative Immunology Microbiology and Infectious Diseases, Jul 1, 2005

This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from go... more This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from golden-mantled ground squirrels (Spermophilus lateralis, GMGS), a hibernating mammal, at a variety of in vitro incubation temperatures to determine whether this aspect of immune function is effective at low body temperatures. LPS-binding by ground squirrel macrophages was compared to that of rat splenic macrophages. Macrophages were collected from squirrels at discreet stages in their annual cycle and incubated with fluorescein-labeled LPS (LPS-FITC). The percentage of GMGS that bound LPS-FITC did not change as a function of hibernation season or as a function of incubation temperature. The total amount of LPS-FITC bound per cell was similarly unaffected by season or temperature, however, macrophages from torpid squirrels bound more LPS-FITC than cells from normothermic squirrels. Macrophages of golden-mantled ground squirrels bind LPS at a wide range of temperatures throughout their annual cycle; an ability shared between hibernators and nonhibernators alike.

Advances in Physiology Education, Dec 1, 2008

IntechOpen eBooks, Jul 14, 2021

The interaction of CD4 with MHC class II during helper T-cell activation and effector function is... more The interaction of CD4 with MHC class II during helper T-cell activation and effector function is required for the initiation of an adaptive immune response in all gnathostomes. CD4 is comprised of four immunoglobulin domains but most likely arose from an ancestral two-domain homolog. The distal, D1 domain of CD4 binds to non-polymorphic regions of the MHC molecule, but despite the absolute requirement for this interaction, the sequence and structure of this domain are not well conserved through phylogeny. Conversely, the proximal, D4 domain of CD4 contains the binding site of the cytokine IL-16 and is highly conserved in its amino acid structure. IL-16 is a cytokine that has been described in a wide variety of invertebrate and vertebrate species. The CD4-binding residues on IL-16 are highly conserved throughout phylogeny, allowing for promiscuous binding of IL-16 to CD4 between members of unrelated taxa. This chapter aims to present structural, and functional support for the hypothesis that the CD4 co-receptor of the TCR arose from a primordial receptor for IL-16.

The immune system is a vital physiological component that affords animals protection from disease... more The immune system is a vital physiological component that affords animals protection from disease and is composed of innate and adaptive mechanisms that rely on cellular and dissolved components. The serum complement system is a series of dissolved proteins that protect against a variety of pathogens. The activity of complement in serum can be determined by its ability to lyse red blood cells in vitro. Here, we describe a modification of a standard complement hemolysis assay that makes an interesting and informative laboratory exercise suitable for a variety of courses including physiology.

Developmental and Comparative Immunology, Jul 1, 2002

Little is known about the changes in the immune system that coincide with the annual cycle of hib... more Little is known about the changes in the immune system that coincide with the annual cycle of hibernating mammals. This study investigates classical pathway complement activity in the serum of the golden-mantled ground squirrel, a mammalian hibernator. Complement activity varied signi®cantly among discreet stages of the annual cycle and is lowest during torpor and greatest during stages of arousal. C3 mRNA levels follow a pattern similar to that of complement-mediated hemolysis throughout the year but do not vary signi®cantly among hibernation states. The classical pathway of the serum complement system is able to function in vitro at 5 8C, although at a slower rate than at 34 8C. The classical pathway of the serum complement system is active throughout all phases of the annual cycle of the golden-mantled ground squirrel.

Physiological and Biochemical Zoology, May 1, 1999

The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understoo... more The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understood. In order to examine whether rates of substrate oxidation vary as a function of hibernation, liver mitochondria were isolated from telemetered ground squirrels (Spermophilus lateralis) in five phases of their annual hibernation cycle: summer active, and torpid, interbout aroused, entrance, and arousing hibernators. Rates of state 3 and state 4 respiration were measured in vitro at 25 degrees C. Relative to mitochondria from summer-active animals, rates of state 3 respiration were significantly depressed in mitochondria from torpid animals yet fully restored during interbout arousals. These findings indicate that a depression of ADP-dependent respiration in liver mitochondria occurs during torpor and is reversed during the interbout arousals to euthermia. Because this inhibition was determined to be temporally independent of entrance and arousal, it is unlikely that active suppression of state 3 respiration causes entrance into torpor by facilitating metabolic depression. In contrast to the observed depression of state 3 respiration in torpid animals, state 4 respiration did not differ significantly among any of the five groups, suggesting that alterations in proton leak are not contributing appreciably to downregulation of respiration in hibernation.

Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, May 20, 1997

The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte p... more The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte populations, and serum complement levels was examined in the northern leopard frog, Rana pipiens. Proliferation of T lymphocytes in response to phytohemagglutinin stimulation was significantly decreased in frogs kept for 2, 3, and 5 months at 5 degrees C compared to that of animals kept at 22 degrees C. A significant increase in the average percentage of neutrophils and a decrease in the mean percentage of eosinophils was observed in the blood of frogs held for 5 months in the cold compared to animals held at 22 degrees C for the same length of time. Mean serum complement activity after 1 month at 5 degrees C was significantly reduced in comparison to animals held at 22 degrees C and was not detectable after 5 months in the cold. Recovery of complement levels at room temperature (22 degrees C) was also examined after cold exposure. Complement levels were significantly higher than controls (at 22 degrees C) in frogs returned to 22 degrees C for 7 and 14 days after 5 months in the cold. After frogs were held at 5 degrees C for 1 month, serum complement levels increased significantly within 2 days after returning to 22 degrees C and continued to rise 5 and 9 days after warming. Injections with Aeromonas hydrophila following a 5-week exposure to 5 degrees C failed to cause death or observable symptoms of disease in frogs that were returned to 22 degrees C.

Interleukins - The Immune and Non-Immune Systems’ Related Cytokines, 2021

The interaction of CD4 with MHC class II during helper T-cell activation and effector function is... more The interaction of CD4 with MHC class II during helper T-cell activation and effector function is required for the initiation of an adaptive immune response in all gnathostomes. CD4 is comprised of four immunoglobulin domains but most likely arose from an ancestral two-domain homolog. The distal, D1 domain of CD4 binds to non-polymorphic regions of the MHC molecule, but despite the absolute requirement for this interaction, the sequence and structure of this domain are not well conserved through phylogeny. Conversely, the proximal, D4 domain of CD4 contains the binding site of the cytokine IL-16 and is highly conserved in its amino acid structure. IL-16 is a cytokine that has been described in a wide variety of invertebrate and vertebrate species. The CD4-binding residues on IL-16 are highly conserved throughout phylogeny, allowing for promiscuous binding of IL-16 to CD4 between members of unrelated taxa. This chapter aims to present structural, and functional support for the hypoth...

IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate... more IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate to a site of inflammation or tissue damage. IL-16 is a ligand for CD4 and binds at the proximal, D4 region well outside of the binding site for MHC class II. The sequence and structure of IL-16 is highly conserved among disparate vertebrates but CD4 is less well conserved and is highly variable at the distal, D1region that binds to MHC class II during T-cell activation and effector function. Conversely, the D4 region, like its ligand, is very highly conserved. This conservation of sequence and structure suggests that the role of CD4 as a receptor for IL-16 has been retained throughout vertebrate phylogeny. Because of the conservation of this receptor: ligand pair, we set out to demonstrate that recombinant human IL-16 (rhIL-16) can elicit the same effects on lymphocytes from the amphibian Xenopus laevis as it would on human lymphocytes. Our data suggest that rhIL-16 attracts a population of CD4+ lymphocytes with a regulatory phenotype.

Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology, 1997

The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte p... more The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte populations, and serum complement levels was examined in the northern leopard frog, Rana pipiens. Proliferation of T lymphocytes in response to phytohemagglutinin stimulation was significantly decreased in frogs kept for 2, 3, and 5 months at 5 degrees C compared to that of animals kept at 22 degrees C. A significant increase in the average percentage of neutrophils and a decrease in the mean percentage of eosinophils was observed in the blood of frogs held for 5 months in the cold compared to animals held at 22 degrees C for the same length of time. Mean serum complement activity after 1 month at 5 degrees C was significantly reduced in comparison to animals held at 22 degrees C and was not detectable after 5 months in the cold. Recovery of complement levels at room temperature (22 degrees C) was also examined after cold exposure. Complement levels were significantly higher than controls (at 22 degrees C) in frogs returned to 22 degrees C for 7 and 14 days after 5 months in the cold. After frogs were held at 5 degrees C for 1 month, serum complement levels increased significantly within 2 days after returning to 22 degrees C and continued to rise 5 and 9 days after warming. Injections with Aeromonas hydrophila following a 5-week exposure to 5 degrees C failed to cause death or observable symptoms of disease in frogs that were returned to 22 degrees C.

The interaction of CD4 with MHC class II during helper T-cell activation and effector function is... more The interaction of CD4 with MHC class II during helper T-cell activation and effector function is required for the initiation of an adaptive immune response in all gnathostomes. CD4 is comprised of four immunoglobulin domains but most likely arose from an ancestral two-domain homolog. The distal, D1 domain of CD4 binds to non-polymorphic regions of the MHC molecule, but despite the absolute requirement for this interaction, the sequence and structure of this domain are not well conserved through phylogeny. Conversely, the proximal, D4 domain of CD4 contains the binding site of the cytokine IL-16 and is highly conserved in its amino acid structure. IL-16 is a cytokine that has been described in a wide variety of invertebrate and vertebrate species. The CD4-binding residues on IL-16 are highly conserved throughout phylogeny, allowing for promiscuous binding of IL-16 to CD4 between members of unrelated taxa. This chapter aims to present structural, and functional support for the hypoth...

Transplantation, Dec 1, 2004

In vertebrates from man to frogs, the heat shock protein (hsp) gp96 elicits T-cell responses agai... more In vertebrates from man to frogs, the heat shock protein (hsp) gp96 elicits T-cell responses against antigenic peptides that it chaperones. In Xenopus, immunization with gp96 purified from normal tissues accelerates rejection of MHC identical, minor histocompatibility (H) antigen-disparate skin grafts in vivo and induces MHC-restricted CTL responses in vitro. Also in Xenopus, gp96 derived from MHC class I-negative tumors elicits peptide-specific responses against these tumors in vivo and MHC-unrestricted CD8 killing in vitro. We have developed an adoptive cell transfer protocol to further characterize these gp96-stimulated Xenopus effectors in vivo. Carboxyfluorescein diacetate succinimidyl ester (CFSE)-stained splenocytes from cloned LG-6 donor frogs immunized with gp96 purified from minor H-antigen-disparate LG-15 tissues were transferred into LG-6 recipients bearing a LG-15 minor H antigen (ag)-disparate skin graft. Primed anti-LG-15 but not naive CFSE T cells accumulated and divided in the spleen of allografted recipients to a greater extent than in those of autografted recipients. Similar accumulation and division occurred when CD8 T cells primed by 15/0 tumor-derived gp96 were transferred to an isogeneic recipient bearing the same MHC class I-negative tumor. Furthermore, the transfer of such primed antitumor splenocytes into naive recipients before tumor challenge delayed the appearance of tumors. These data provide new in vivo evidence that in frogs as in mammals, gp96 can prime CD8 T cells against antigens they chaperone. In addition, at least in Xenopus, gp96 can prime CD8(+) T-cell effectors that are not MHC restricted.

Physiological and Biochemical Zoology, 1999

The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understoo... more The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understood. In order to examine whether rates of substrate oxidation vary as a function of hibernation, liver mitochondria were isolated from telemetered ground squirrels (Spermophilus lateralis) in five phases of their annual hibernation cycle: summer active, and torpid, interbout aroused, entrance, and arousing hibernators. Rates of state 3 and state 4 respiration were measured in vitro at 25 degrees C. Relative to mitochondria from summer-active animals, rates of state 3 respiration were significantly depressed in mitochondria from torpid animals yet fully restored during interbout arousals. These findings indicate that a depression of ADP-dependent respiration in liver mitochondria occurs during torpor and is reversed during the interbout arousals to euthermia. Because this inhibition was determined to be temporally independent of entrance and arousal, it is unlikely that active suppression of state 3 respiration causes entrance into torpor by facilitating metabolic depression. In contrast to the observed depression of state 3 respiration in torpid animals, state 4 respiration did not differ significantly among any of the five groups, suggesting that alterations in proton leak are not contributing appreciably to downregulation of respiration in hibernation.

Archives of Autoimmune Diseases, 2020

IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate... more IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate to a site of inflammation or tissue damage. IL-16 is a ligand for CD4 and binds at the proximal, D4 region well outside of the binding site for MHC class II. The sequence and structure of IL-16 is highly conserved among disparate vertebrates but CD4 is less well conserved and is highly variable at the distal, D1region that binds to MHC class II during T-cell activation and effector function. Conversely, the D4 region, like its ligand, is very highly conserved. This conservation of sequence and structure suggests that the role of CD4 as a receptor for IL-16 has been retained throughout vertebrate phylogeny. Because
of the conservation of this receptor: ligand pair, we set out to demonstrate that recombinant human IL-16 (rhIL-16) can elicit the same effects on lymphocytes from the amphibian Xenopus laevis as it would
on human lymphocytes. Our data suggest that rhIL-16 attracts a population of CD4+ lymphocytes with a regulatory phenotype.

Cytokine, 2020

The D1 domain of the CD4 co-receptor interacts with MHC class II during Helper CD4+ Th-cell activ... more The D1 domain of the CD4 co-receptor interacts with MHC class II during Helper CD4+ Th-cell activation and effector function in all gnathostomes but the sequence and structure of this region are not well conserved through phylogeny. Conversely, the proximal D4 domain of CD4 is the binding site of the cytokine IL-16 and is highly conserved, allowing for promiscuous binding of IL-16 to CD4 between disparate gnathostomes. We report here that recombinant human IL-16 (rhIL-16) bound to Xenopus lymphocytes to allow separation on a magnetic column. Incubation with rhIL-16 resulted in an increased expression of MHC class II mRNA by Xenopus CD8− cells more than by CD8+ cells. An in vivo assay demonstrated that rhIL-16 can recruit lymphocytes of Xenopus frogs. Our data suggest that a subset of Xenopus laevis lymphocytes express a CD4 homolog on their surface that is capable of binding IL-16. These results imply that CD4 most likely arose from a primordial cytokine receptor.

Immunogenetics, 2005

CD91, the endocytic receptor for α 2 -macroglobulin (α 2 M), mediates the internalization of cert... more CD91, the endocytic receptor for α 2 -macroglobulin (α 2 M), mediates the internalization of certain heat shock proteins (hsps) and the cross-presentation of peptides they chaperone by antigen-presenting cells. The phylogenetic conservation of the immunologically active CD91 ligands, α 2 M and hsps, is consistent with the idea of an ancestral system of immune surveillance. We have further explored this hypothesis by taking advantage of the frog Xenopus, and asked how conserved is CD91 and whether the expression of CD91 is differentially modulated during immune responses of class I-positive adult and naturally class I-negative larvae. We have identified a Xenopus CD91 gene homologue that displays high sequence identity (>65%) with other CD91 homologues and contains an additional distinctive cytoplasmic NPXY motif. Phylogenetic analysis indicates that CD91 homologues branch as a monophyletic group distinct from other LDLRs; this suggests an origin of CD91 contemporary with that of metazoans. A 14-kb transcript is detected by Northern blotting in most adult and larval tissues, including lymphoid tissues. RT-PCR study reveals that CD91 is expressed in most cell types, including adult macrophages, B and T cells as well as in splenocytes and thymocytes from naturally MHC class I negative larvae. CD91 is markedly up-regulated in vivo by adult peritoneal leukocytes following bacterial and viral stimulation; it is constitutively expressed on class I-negative larval perito-neal leukocytes at high levels and cannot be further upregulated by such stimulation. These data are in agreement with a conserved role of CD91 in immunity.

Springer eBooks, 2000

Lymphocyte proliferation is a prerequisite for most aspects of the mammalian acquired immune resp... more Lymphocyte proliferation is a prerequisite for most aspects of the mammalian acquired immune response. Splenic lymphocytes from golden-mantled ground squirrels collected at different phases of hibernation were stimulated in vitro with several mitogens to measure proliferative ability at several temperatures. No differences were seen in lymphocyte proliferation at any of the temperatures tested between animals at different stages of hibernation. No proliferation was detected at 5°C. T cell mitogens induced significantly higher proliferation at 37°C than at 27°C in lymphocytes from both summer and hibenrating animals. A B cell mitogen induced similar proliferation at both 27° and 37°C in cells from summer and hibernating animals. Lymphoocyte proliferation appears to be highly temperature-dependent in both summer and hibernating animals. Therefore, interbout arousals are essential for the production of a successful acquired immune response during hibernation.

Comparative Immunology Microbiology and Infectious Diseases, Jul 1, 2005

This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from go... more This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from golden-mantled ground squirrels (Spermophilus lateralis, GMGS), a hibernating mammal, at a variety of in vitro incubation temperatures to determine whether this aspect of immune function is effective at low body temperatures. LPS-binding by ground squirrel macrophages was compared to that of rat splenic macrophages. Macrophages were collected from squirrels at discreet stages in their annual cycle and incubated with fluorescein-labeled LPS (LPS-FITC). The percentage of GMGS that bound LPS-FITC did not change as a function of hibernation season or as a function of incubation temperature. The total amount of LPS-FITC bound per cell was similarly unaffected by season or temperature, however, macrophages from torpid squirrels bound more LPS-FITC than cells from normothermic squirrels. Macrophages of golden-mantled ground squirrels bind LPS at a wide range of temperatures throughout their annual cycle; an ability shared between hibernators and nonhibernators alike.

Advances in Physiology Education, Dec 1, 2008

IntechOpen eBooks, Jul 14, 2021

The interaction of CD4 with MHC class II during helper T-cell activation and effector function is... more The interaction of CD4 with MHC class II during helper T-cell activation and effector function is required for the initiation of an adaptive immune response in all gnathostomes. CD4 is comprised of four immunoglobulin domains but most likely arose from an ancestral two-domain homolog. The distal, D1 domain of CD4 binds to non-polymorphic regions of the MHC molecule, but despite the absolute requirement for this interaction, the sequence and structure of this domain are not well conserved through phylogeny. Conversely, the proximal, D4 domain of CD4 contains the binding site of the cytokine IL-16 and is highly conserved in its amino acid structure. IL-16 is a cytokine that has been described in a wide variety of invertebrate and vertebrate species. The CD4-binding residues on IL-16 are highly conserved throughout phylogeny, allowing for promiscuous binding of IL-16 to CD4 between members of unrelated taxa. This chapter aims to present structural, and functional support for the hypothesis that the CD4 co-receptor of the TCR arose from a primordial receptor for IL-16.

The immune system is a vital physiological component that affords animals protection from disease... more The immune system is a vital physiological component that affords animals protection from disease and is composed of innate and adaptive mechanisms that rely on cellular and dissolved components. The serum complement system is a series of dissolved proteins that protect against a variety of pathogens. The activity of complement in serum can be determined by its ability to lyse red blood cells in vitro. Here, we describe a modification of a standard complement hemolysis assay that makes an interesting and informative laboratory exercise suitable for a variety of courses including physiology.

Developmental and Comparative Immunology, Jul 1, 2002

Little is known about the changes in the immune system that coincide with the annual cycle of hib... more Little is known about the changes in the immune system that coincide with the annual cycle of hibernating mammals. This study investigates classical pathway complement activity in the serum of the golden-mantled ground squirrel, a mammalian hibernator. Complement activity varied signi®cantly among discreet stages of the annual cycle and is lowest during torpor and greatest during stages of arousal. C3 mRNA levels follow a pattern similar to that of complement-mediated hemolysis throughout the year but do not vary signi®cantly among hibernation states. The classical pathway of the serum complement system is able to function in vitro at 5 8C, although at a slower rate than at 34 8C. The classical pathway of the serum complement system is active throughout all phases of the annual cycle of the golden-mantled ground squirrel.

Physiological and Biochemical Zoology, May 1, 1999

The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understoo... more The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understood. In order to examine whether rates of substrate oxidation vary as a function of hibernation, liver mitochondria were isolated from telemetered ground squirrels (Spermophilus lateralis) in five phases of their annual hibernation cycle: summer active, and torpid, interbout aroused, entrance, and arousing hibernators. Rates of state 3 and state 4 respiration were measured in vitro at 25 degrees C. Relative to mitochondria from summer-active animals, rates of state 3 respiration were significantly depressed in mitochondria from torpid animals yet fully restored during interbout arousals. These findings indicate that a depression of ADP-dependent respiration in liver mitochondria occurs during torpor and is reversed during the interbout arousals to euthermia. Because this inhibition was determined to be temporally independent of entrance and arousal, it is unlikely that active suppression of state 3 respiration causes entrance into torpor by facilitating metabolic depression. In contrast to the observed depression of state 3 respiration in torpid animals, state 4 respiration did not differ significantly among any of the five groups, suggesting that alterations in proton leak are not contributing appreciably to downregulation of respiration in hibernation.

Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, May 20, 1997

The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte p... more The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte populations, and serum complement levels was examined in the northern leopard frog, Rana pipiens. Proliferation of T lymphocytes in response to phytohemagglutinin stimulation was significantly decreased in frogs kept for 2, 3, and 5 months at 5 degrees C compared to that of animals kept at 22 degrees C. A significant increase in the average percentage of neutrophils and a decrease in the mean percentage of eosinophils was observed in the blood of frogs held for 5 months in the cold compared to animals held at 22 degrees C for the same length of time. Mean serum complement activity after 1 month at 5 degrees C was significantly reduced in comparison to animals held at 22 degrees C and was not detectable after 5 months in the cold. Recovery of complement levels at room temperature (22 degrees C) was also examined after cold exposure. Complement levels were significantly higher than controls (at 22 degrees C) in frogs returned to 22 degrees C for 7 and 14 days after 5 months in the cold. After frogs were held at 5 degrees C for 1 month, serum complement levels increased significantly within 2 days after returning to 22 degrees C and continued to rise 5 and 9 days after warming. Injections with Aeromonas hydrophila following a 5-week exposure to 5 degrees C failed to cause death or observable symptoms of disease in frogs that were returned to 22 degrees C.

Interleukins - The Immune and Non-Immune Systems’ Related Cytokines, 2021

The interaction of CD4 with MHC class II during helper T-cell activation and effector function is... more The interaction of CD4 with MHC class II during helper T-cell activation and effector function is required for the initiation of an adaptive immune response in all gnathostomes. CD4 is comprised of four immunoglobulin domains but most likely arose from an ancestral two-domain homolog. The distal, D1 domain of CD4 binds to non-polymorphic regions of the MHC molecule, but despite the absolute requirement for this interaction, the sequence and structure of this domain are not well conserved through phylogeny. Conversely, the proximal, D4 domain of CD4 contains the binding site of the cytokine IL-16 and is highly conserved in its amino acid structure. IL-16 is a cytokine that has been described in a wide variety of invertebrate and vertebrate species. The CD4-binding residues on IL-16 are highly conserved throughout phylogeny, allowing for promiscuous binding of IL-16 to CD4 between members of unrelated taxa. This chapter aims to present structural, and functional support for the hypoth...

IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate... more IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate to a site of inflammation or tissue damage. IL-16 is a ligand for CD4 and binds at the proximal, D4 region well outside of the binding site for MHC class II. The sequence and structure of IL-16 is highly conserved among disparate vertebrates but CD4 is less well conserved and is highly variable at the distal, D1region that binds to MHC class II during T-cell activation and effector function. Conversely, the D4 region, like its ligand, is very highly conserved. This conservation of sequence and structure suggests that the role of CD4 as a receptor for IL-16 has been retained throughout vertebrate phylogeny. Because of the conservation of this receptor: ligand pair, we set out to demonstrate that recombinant human IL-16 (rhIL-16) can elicit the same effects on lymphocytes from the amphibian Xenopus laevis as it would on human lymphocytes. Our data suggest that rhIL-16 attracts a population of CD4+ lymphocytes with a regulatory phenotype.

Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology, 1997

The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte p... more The effect of exposure to low temperatures (5 degrees C) on lymphocyte proliferation, leukocyte populations, and serum complement levels was examined in the northern leopard frog, Rana pipiens. Proliferation of T lymphocytes in response to phytohemagglutinin stimulation was significantly decreased in frogs kept for 2, 3, and 5 months at 5 degrees C compared to that of animals kept at 22 degrees C. A significant increase in the average percentage of neutrophils and a decrease in the mean percentage of eosinophils was observed in the blood of frogs held for 5 months in the cold compared to animals held at 22 degrees C for the same length of time. Mean serum complement activity after 1 month at 5 degrees C was significantly reduced in comparison to animals held at 22 degrees C and was not detectable after 5 months in the cold. Recovery of complement levels at room temperature (22 degrees C) was also examined after cold exposure. Complement levels were significantly higher than controls (at 22 degrees C) in frogs returned to 22 degrees C for 7 and 14 days after 5 months in the cold. After frogs were held at 5 degrees C for 1 month, serum complement levels increased significantly within 2 days after returning to 22 degrees C and continued to rise 5 and 9 days after warming. Injections with Aeromonas hydrophila following a 5-week exposure to 5 degrees C failed to cause death or observable symptoms of disease in frogs that were returned to 22 degrees C.

The interaction of CD4 with MHC class II during helper T-cell activation and effector function is... more The interaction of CD4 with MHC class II during helper T-cell activation and effector function is required for the initiation of an adaptive immune response in all gnathostomes. CD4 is comprised of four immunoglobulin domains but most likely arose from an ancestral two-domain homolog. The distal, D1 domain of CD4 binds to non-polymorphic regions of the MHC molecule, but despite the absolute requirement for this interaction, the sequence and structure of this domain are not well conserved through phylogeny. Conversely, the proximal, D4 domain of CD4 contains the binding site of the cytokine IL-16 and is highly conserved in its amino acid structure. IL-16 is a cytokine that has been described in a wide variety of invertebrate and vertebrate species. The CD4-binding residues on IL-16 are highly conserved throughout phylogeny, allowing for promiscuous binding of IL-16 to CD4 between members of unrelated taxa. This chapter aims to present structural, and functional support for the hypoth...

Transplantation, Dec 1, 2004

In vertebrates from man to frogs, the heat shock protein (hsp) gp96 elicits T-cell responses agai... more In vertebrates from man to frogs, the heat shock protein (hsp) gp96 elicits T-cell responses against antigenic peptides that it chaperones. In Xenopus, immunization with gp96 purified from normal tissues accelerates rejection of MHC identical, minor histocompatibility (H) antigen-disparate skin grafts in vivo and induces MHC-restricted CTL responses in vitro. Also in Xenopus, gp96 derived from MHC class I-negative tumors elicits peptide-specific responses against these tumors in vivo and MHC-unrestricted CD8 killing in vitro. We have developed an adoptive cell transfer protocol to further characterize these gp96-stimulated Xenopus effectors in vivo. Carboxyfluorescein diacetate succinimidyl ester (CFSE)-stained splenocytes from cloned LG-6 donor frogs immunized with gp96 purified from minor H-antigen-disparate LG-15 tissues were transferred into LG-6 recipients bearing a LG-15 minor H antigen (ag)-disparate skin graft. Primed anti-LG-15 but not naive CFSE T cells accumulated and divided in the spleen of allografted recipients to a greater extent than in those of autografted recipients. Similar accumulation and division occurred when CD8 T cells primed by 15/0 tumor-derived gp96 were transferred to an isogeneic recipient bearing the same MHC class I-negative tumor. Furthermore, the transfer of such primed antitumor splenocytes into naive recipients before tumor challenge delayed the appearance of tumors. These data provide new in vivo evidence that in frogs as in mammals, gp96 can prime CD8 T cells against antigens they chaperone. In addition, at least in Xenopus, gp96 can prime CD8(+) T-cell effectors that are not MHC restricted.

Physiological and Biochemical Zoology, 1999

The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understoo... more The biochemical mechanisms by which hibernators cool as they enter torpor are not fully understood. In order to examine whether rates of substrate oxidation vary as a function of hibernation, liver mitochondria were isolated from telemetered ground squirrels (Spermophilus lateralis) in five phases of their annual hibernation cycle: summer active, and torpid, interbout aroused, entrance, and arousing hibernators. Rates of state 3 and state 4 respiration were measured in vitro at 25 degrees C. Relative to mitochondria from summer-active animals, rates of state 3 respiration were significantly depressed in mitochondria from torpid animals yet fully restored during interbout arousals. These findings indicate that a depression of ADP-dependent respiration in liver mitochondria occurs during torpor and is reversed during the interbout arousals to euthermia. Because this inhibition was determined to be temporally independent of entrance and arousal, it is unlikely that active suppression of state 3 respiration causes entrance into torpor by facilitating metabolic depression. In contrast to the observed depression of state 3 respiration in torpid animals, state 4 respiration did not differ significantly among any of the five groups, suggesting that alterations in proton leak are not contributing appreciably to downregulation of respiration in hibernation.

Archives of Autoimmune Diseases, 2020

IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate... more IL-16 is a pleiotropic, pro-inflammatory cytokine that induces regulatory CD4+ T cells to migrate to a site of inflammation or tissue damage. IL-16 is a ligand for CD4 and binds at the proximal, D4 region well outside of the binding site for MHC class II. The sequence and structure of IL-16 is highly conserved among disparate vertebrates but CD4 is less well conserved and is highly variable at the distal, D1region that binds to MHC class II during T-cell activation and effector function. Conversely, the D4 region, like its ligand, is very highly conserved. This conservation of sequence and structure suggests that the role of CD4 as a receptor for IL-16 has been retained throughout vertebrate phylogeny. Because
of the conservation of this receptor: ligand pair, we set out to demonstrate that recombinant human IL-16 (rhIL-16) can elicit the same effects on lymphocytes from the amphibian Xenopus laevis as it would
on human lymphocytes. Our data suggest that rhIL-16 attracts a population of CD4+ lymphocytes with a regulatory phenotype.

Cytokine, 2020

The D1 domain of the CD4 co-receptor interacts with MHC class II during Helper CD4+ Th-cell activ... more The D1 domain of the CD4 co-receptor interacts with MHC class II during Helper CD4+ Th-cell activation and effector function in all gnathostomes but the sequence and structure of this region are not well conserved through phylogeny. Conversely, the proximal D4 domain of CD4 is the binding site of the cytokine IL-16 and is highly conserved, allowing for promiscuous binding of IL-16 to CD4 between disparate gnathostomes. We report here that recombinant human IL-16 (rhIL-16) bound to Xenopus lymphocytes to allow separation on a magnetic column. Incubation with rhIL-16 resulted in an increased expression of MHC class II mRNA by Xenopus CD8− cells more than by CD8+ cells. An in vivo assay demonstrated that rhIL-16 can recruit lymphocytes of Xenopus frogs. Our data suggest that a subset of Xenopus laevis lymphocytes express a CD4 homolog on their surface that is capable of binding IL-16. These results imply that CD4 most likely arose from a primordial cytokine receptor.

Immunogenetics, 2005

CD91, the endocytic receptor for α 2 -macroglobulin (α 2 M), mediates the internalization of cert... more CD91, the endocytic receptor for α 2 -macroglobulin (α 2 M), mediates the internalization of certain heat shock proteins (hsps) and the cross-presentation of peptides they chaperone by antigen-presenting cells. The phylogenetic conservation of the immunologically active CD91 ligands, α 2 M and hsps, is consistent with the idea of an ancestral system of immune surveillance. We have further explored this hypothesis by taking advantage of the frog Xenopus, and asked how conserved is CD91 and whether the expression of CD91 is differentially modulated during immune responses of class I-positive adult and naturally class I-negative larvae. We have identified a Xenopus CD91 gene homologue that displays high sequence identity (>65%) with other CD91 homologues and contains an additional distinctive cytoplasmic NPXY motif. Phylogenetic analysis indicates that CD91 homologues branch as a monophyletic group distinct from other LDLRs; this suggests an origin of CD91 contemporary with that of metazoans. A 14-kb transcript is detected by Northern blotting in most adult and larval tissues, including lymphoid tissues. RT-PCR study reveals that CD91 is expressed in most cell types, including adult macrophages, B and T cells as well as in splenocytes and thymocytes from naturally MHC class I negative larvae. CD91 is markedly up-regulated in vivo by adult peritoneal leukocytes following bacterial and viral stimulation; it is constitutively expressed on class I-negative larval perito-neal leukocytes at high levels and cannot be further upregulated by such stimulation. These data are in agreement with a conserved role of CD91 in immunity.