Toxicity to Candida albicans mediated by human serum and peripheral blood mononuclear cells (original) (raw)
Related papers
FEMS Immunology & Medical Microbiology, 2007
Although most individuals are colonized with Candida albicans, only patients with insufficient or nonfunctional phagocytes develop life-threatening C. albicans disease. Because recognition of bacterial pathogens through phagocyte receptors for IgG (FcgR) is known to augment phagocyte responses, we postulated that antibody opsonization would enhance monocyte damage to C. albicans and subsequent tumor necrosis factor-a (TNF-a) production. After exposure to the human monocytic cell line THP-1, opsonized yeast showed an 89% decrease in metabolic activity, compared with 40% for unopsonized yeast (P o 0.05). Culture supernatants contained 1316 pg mL À1 of TNF-a after monocytes were exposed to opsonized yeast vs. 341 pg mL À1 for unopsonized yeast (P = 0.003). Similar results were obtained using peripheral blood mononuclear cells. Antibody opsonization of C. albicans germ tubes enhanced TNF-a production but did not affect organism damage. Antibody-dependent and antibody-independent factors were found to act synergistically to increase TNF-a production. ERK activation was important for both antibody-dependent and antibody-independent stimulation of TNF-a production, but not for monocyte-mediated organism damage. These data suggest that FcgR cooperates positively with antibody-independent recognition mechanisms in what may be a novel link between innate and adaptive immunity to C. albicans.
Journal of general microbiology, 1990
Two major proteoglycan constituents (designated F1 and F2) of the cell wall of Candida albicans were separated by ion-exchange chromatography from a crude carbohydrate-rich extract (GMP), and investigated for their chemical and molecular composition, antigenicity and immunomodulatory properties in cultures of human peripheral blood mononuclear cells (PBMC). Both fractions consisted predominantly of Periodic acid-Schiff (PAS) and concanavalin A (Con A)-reactive material consisting of greater than 90% mannose, 3-5% protein and small amounts of phosphorus; each was recognized by an anti-Candida rabbit serum as well as by a monoclonal antibody (mAb AF1) directed against an oligosaccharide epitope present on the fungal cell surface. When F1 and F2 were subjected to SDS-PAGE, transblotted and stained with enzyme-conjugated mAb AF1 or Con A, most of the antibody or lectin bound to high molecular mass (greater than 200 kDa) polydisperse material, some of which was present in F2 (as in the s...
Journal of Medical Microbiology, 1986
Glutaraldehyde-inactivated cells and cell-wall fractions of Candida albicans were studied for their capacity to induce or inhibit the in-vitro proliferation of human peripheral blood mononuclear cells (PBMC), as measured by 3H-thymidine incorporation. Both the intact cells (CA) and a phosphorylated gluco-mannanprotein complex of the cell wall (GMP), in pg doses, were strong inducers of PBMC proliferation, with a peak of activity at 6-9 days of culture and varying with the PBMC donor. A significant but much lower proliferation was observed on exposure of PBMC to a low-protein (< 3% by weight) mannan component (M) of the cell wall. Both a hot-alkali extracted mannan-protein complex (M-alk), comparable to GMP in crude chemical composition, and an alkali-insoluble cell-wall glucan (GG) were inactive. None of the Candida fractions induced a lymphoproliferation of umbilical cord blood cells and all fractions, except GG, were equally effective in binding human anti-Candida antibodies as shown by a sensitive ELISA-inhibition assay. Moreover, a monoclonal antibody against the class I1 determinant of the HLA complex inhibited PBMC proliferation irrespective of the Candida antigen used. Taken together, the data shows that in inducing lymphoproliferation, Candida fractions act as specific antigens rather than as non-specific mitogens. Use of intact Candida cells and chemically-defined cell-wall components appears preferable to use of undefined antigenic mixtures as stimulators of PBMC proliferation.
Cellular Immunology, 1989
In this study, the major histocompatibility complex-unrestricted cytotoxic et&tots elicited in human peripheral blood mononuclear cells (PBMC) by a mannoprotein (MP) component from the cell wall of the human indigenous microrganism Candida albicans have been compared with those obtained by stimulation with interleukin 2. (Interleukin 2-activated killer cells: LAK). It has been found that MP-induced lytic effecters were substantially similar to LAK in potency, target specificity, and type of precursor/effecter cells. In both cases, natural killer (NK)susceptible and NK-resistant targets as well as fresh tumor (glioma) cells were efficiently killed by a population of effecters showing a predominant CD3-, CDl6+ phenotype. However, the precursors of MP-induced killers were highly sensitive to the lysosomotropic toxic drug L-leutine methyl ester (Leu-OME) whereas the generation of LAK cells was unaffected by this drug. The Leu-OME sensitivity of MP-induced cytotoxicity generation was not due to a nonspecific effect on antigen-presenting cells or inhibition of cell proliferation. In addition, the generation of MP-induced killer cells was totally abrogated by treatment with CD 16 antibodies and complement, whereas a minor but significant fraction of LAK precursors was not susceptible to the above treatment. These results indicate that a defined component(s) ofthe cell wall of C. albicans has some properties of biological response modifiers in cultures of human PBMC in vitro. 0 1989 Academic Press, Inc. ' Abbreviations used: IL-2, interleukin 2; LAK, interleukin 2-activated killer cells; PBMC, peripheral blood mononuclear cells; MP, mannoprotein; MHC, major histocompatibility complex; L.eu-OME (Lleucine methyl ester); IFN--r, interferon-y; APC, antigen-presenting cells; MAb, monoclonal antibody; BSA, bovine serum albumine; NK, natural killer cells.
Candida albicans induces the release of inflammatory mediators from human peripheral blood monocytes
Inflammation, 1996
Candida albicans (C. albicans) is a major nosocomial pathogen. We examined arachidonic acid (AA) and cytokine production by monocytes stimulated with C. albicans. [14C]-AA labeled monocytes released 8.9 ±2.3% of the incorporated AA following stimulation with live C. albicans (C. albicans: monocyte of 16∶1) (P=0.0002). Prior studies indicate that solubleα-mannans andβ-glucans antagonize mannose andβ-glucan receptors, respectively. Preincubation of monocytes withα-mannan (100μg/ml) caused 45.8 ±5.7% inhibition of [14C]-AA release, whereasβ-glucan (100μg/ml) yielded 43.7 ±6.0% inhibition (Pβ (IL-1β), tumor necrosis factor-α (TNFα), interleukin-6 (IL-6) and interleukin-8 (IL-8). However, a-mannan orβ-glucan failed to inhibit IL-1β release. These data indicate that C. albicans induces monocytes to release AA and inflammatory cytokines. Furthermore, AA, but not cytokine liberation, is partially mediated by a-mannan andβ-glucan components of the fungus.
A rapid evaluation of phagocytosis and killing of Candida albicans by CD13+ leukocytes
Journal of Immunological Methods, 1997
Flow cytometry can be adopted for routine monitoring of the immune functions of human polymorphonuclear leukocytes Ž. PMNs in several disease states. We recently developed a rapid and reproducible assay for the evaluation of the phagocytosis and killing of Candida albicans blastospores by human PMNs. Whole blood leukocytes were incubated with Ž. opsonized fluorescein isothiocyanate-labeled FITC-labeled blastospores for phagocytosis and killing assays. To discrimi-Ž. nate between ingested, membrane-bound and free C. albicans blastospores, ethidium bromide EtBr was added to the samples prior to the flow cytometric analysis. EtBr induces a loss of green fluorescence in non-phagocytized C. albicans blastospores. Phagocytosis is determined by gating the phagocytes and calculating the percentage of phagocyte-associated green fluorescent cells. Intracellular killing is determined by first lysing phagocytes by hypotonic shock and then adding Ž. propidium iodide PI in order to identify red dead blastospores. Killing is measured in terms of the percentage of double-marked blastospore cells. We suggest that this method is a reliable and inexpensive technique to evaluate the immune Ž. reactivity of PMNs and peripheral blood monocytes PBMs in cases of immunosuppression. q 1997 Elsevier Science B.V.