Girmai Gebru | Addis Ababa University (original) (raw)

Papers by Girmai Gebru

Journal of Reproductive Immunology, 1996

A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cel... more A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cells from BALB/c mice immunised with human sperm cells. The antibody was determined to be an IgG1. The corresponding antigen is present on the whole surface of ejaculated human spermatozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, cat, dog, sheep, boar, bull, horse). In human male genital organs, immunostaining with GZS-1 is observed on sperm cells in the epididymis and the ductus deferens together with the lining epithelium of those organs. No reactivity of sperm cells or germ cell precursors in the testis has been detected. Functional tests using the antibody show a strong inhibitory effect of human sperm in the hamster egg penetration assay. Furthermore, the GZS-1 antigen is detectable on the surface of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal plasma performed under reducing conditions immunostaining was detected at 21-25, 31, 51-54, and 62 kDa. The reaction with human lymphocytes shows one major band at 62 kDa and additional bands at 31 and 54 kDa. The results suggest that the monoclonal antibody GZS-1 may recognise an antigen which is secreted from the epithelial cells of the epididymis and binds to ejaculated spermatozoa as a sperm coating antigen. This component may be involved in the capacitation of the sperm and the acrosome reaction. Molecules that are expressed both on sperm and on immunocompetent cells may be relevant for the regulation of immunological processes or for the development of the related immunological tolerance of sperm in the female reproductive tract.

PLoS ONE, 2021

Introduction Human embryo is well protected in the uterus by the embryonic membrane, although ter... more Introduction Human embryo is well protected in the uterus by the embryonic membrane, although teratogens may cause developmental disruptions after maternal exposure to them during early pregnancy. Most of the risk factors contributing to the development of congenital anomalies are uncertain; however, genetic factors, environmental factors and multifactorial inheritance are found to be risk factors. Regardless of their clinical importance, there are little/no studies conducted directly related to predisposing risk factors in southwestern Ethiopia. Objective The study aimed to determine the associated risk factors with congenital anomalies among newborns in southwestern Ethiopia. Methods Case—control study was conducted on newborns and their mothers in six purposively selected hospitals in southwestern Ethiopia from May 2016 to May 2018. Data was collected after evaluation of the neonates for the presence of congenital anomalies using the standard pretested checklist. The data was ana...

Objective: The objective of the present study was to investigate the sub-chronic toxic effects of... more Objective: The objective of the present study was to investigate the sub-chronic toxic effects of butanol fraction of leaves of M. stenopetala on blood parameters of experimental rats. Methods: For this study the rats were divided into three groups. Group I, the control group received distilled water, while the experimental groups: group II received 500 and group III received 1000mg/kg for 63 days by oral gavage. At the end of the experiment blood samples were collected and examined for hematological and biochemical parameters. Results: Treated rats showed no significant changes on hematological and biochemical parameters except blood glucose level (p<0.05)) as compared with the controls. Conclusion: Although, butanol fraction of leaves of M.stenopetala did not produce adverse effects on hematological & biochemical parameters, further detailed studies should be carried out on other vital organs to recommend its therapeutic use.

1Dep’t of Anatomy, College of Health and Medicine Science, Adigrat University 2Department of Anat... more 1Dep’t of Anatomy, College of Health and Medicine Science, Adigrat University 2Department of Anatomy, College of Health Sciences, Addis Ababa University 3Institute of Biomedical science, College of Health Sciences, Mekelle University theamanuel18@gmail.com Summery Solanumnigrum is commonly called black night shade that belongs to Solanaceae (potato) family. It is a fairly common herb or short-lived perennial shrub, found in many wooded areas, as well as disturbed habitats. Various experimental based scientific studies were conducted in order to investigate the efficacy and safety of S. nigrum extract. The scientific investigation from many research findings shows that this plant has various bioactive ingredients such as alkaloids, solanins, saponins, flavonoids, tannins, steroidal glycoalkaloids, steroidal genin and vitamins. These constituents are responsible for diverse activities including: anti-inflammatory, antibacterial, anti-diabetic, anti-fungal, anti-oxidant, hepatoprotecti...

Ethiopian medical journal, 2014

BACKGROUND Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary ... more BACKGROUND Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary phase, but resulting in active tuberculosis (TB) when the immune system is suppressed. Alpha-crystallin (ACR) is one of the bacterial antigens characterized known to be related to shifting of the bacilli from growth to a non-replicating persistent state. OBJECTIVE To compare the ex-vivo responsiveness of active TB patients, close household contacts and healthy controls to specific Mtb antigens. METHODOLOGY Antigen-specific interferon-gamma (IFN-g) responses were measured to a 16kDa-alpha crystallin (ACR) antigen along with its peptides and other Mtb antigens (ESAT-6, CFP-10, PPD, TB10.3 and Ag85A) in 39 active TB patients, 23 close household contacts and 25 community controls, using ex-vivo ELISPOT RESULT: The proportion of responders to ACR was 36% in active TB patients (76 +/- 14 spot forming cells), 48% in close household contacts (123 +/- 31 spot forming cells) and 76% in community c...

International Journal of Sciences: Basic and Applied Research, 2017

Background : Intrauterine development can be considered as normal development as well as abnormal... more Background : Intrauterine development can be considered as normal development as well as abnormal development. Abnormal development commonly called birth defects occur because of interference of normal development from genetic disorders, environmental factors and the combination of both genetic and environment factors during the critical period of embryogenesis. The present study aimed to evaluate the prevalence and patterns of birth defects at birth in Southwestern Ethiopia. Methods : Institutions based cross-sectional study design was used. Six hospitals were selected from the existing hospitals in southwestern Ethiopia purposively based on case load. The study was conducted from September 2011 to December 2015 during which 45,951 deliveries were attained. All records of births that were occurred in the selected hospitals during the study period were identified from medical records, to locate the birth defect records.Results : Twenty-one different birth defects were recorded. Of t...

Ethiopian Journal of Health Development, Sep 22, 2011

Background: Moringa stenopetala and related species are commonly used in folk medicine for variou... more Background: Moringa stenopetala and related species are commonly used in folk medicine for various human diseases such as antimalarial, antihypertensive, antidiabetic and as antispasmodic. Objective: The aim of the study is to evaluate the effects of aqueous extract of M. stenopetala on blood parameters, and histopathology of liver and kidney in experimental mice. Methods: Fresh leaves of M. stenopetala were collected from Arbaminch area, Southwest Ethiopia, in November 2005. The leaves were dried and extracted with water. Three month-old Swiss albino male mice, which were kept under uniform laboratory conditions, were randomly divided into four groups (one group of controls and three experimental). (The control group was orally given 0.5 ml of distilled water, and groups II, III and IV were given the aqueous leaf extract of M. stenopetala using intragastric tube to achieve the required doses of 600, 750 and 900 mg/kg body weight, respectively once a day at 24 hours intervals for six weeks and then sacrificed). Blood sample was collected from each mouse and examined for hematological and biochemical parameters. Liver and kidney were removed, stained and examined for histopathological profiles. The effects of treatment with aqueous extract of M. stenopetala on hematological, biochemical and histopathology features were compared with control group following standard procedures. Results: Mice treated with 900 mg/kg of the extract per kg of body weight showed a significant increase in body weight compared to the controls (P=0.014). Neither a significant change in the weight nor in histopathology of liver and kidney were observed in the animals treated with aqueous extract of M. stenopetala compared to those of the controls. Serum glucose level (P=0.034) and serum cholesterol level (P=0.016) decreased significantly after six weeks treatment.

Ethiopian Journal of Health Development, 2011

Background: Moringa stenopetala and related species are commonly used in folk medicine for variou... more Background: Moringa stenopetala and related species are commonly used in folk medicine for various human diseases such as antimalarial, antihypertensive, antidiabetic and as antispasmodic. Objective: The aim of the study is to evaluate the effects of aqueous extract of M. stenopetala on blood parameters, and histopathology of liver and kidney in experimental mice. Methods: Fresh leaves of M. stenopetala were collected from Arbaminch area, Southwest Ethiopia, in November 2005. The leaves were dried and extracted with water. Three month-old Swiss albino male mice, which were kept under uniform laboratory conditions, were randomly divided into four groups (one group of controls and three experimental). (The control group was orally given 0.5 ml of distilled water, and groups II, III and IV were given the aqueous leaf extract of M. stenopetala using intragastric tube to achieve the required doses of 600, 750 and 900 mg/kg body weight, respectively once a day at 24 hours intervals for six weeks and then sacrificed). Blood sample was collected from each mouse and examined for hematological and biochemical parameters. Liver and kidney were removed, stained and examined for histopathological profiles. The effects of treatment with aqueous extract of M. stenopetala on hematological, biochemical and histopathology features were compared with control group following standard procedures. Results: Mice treated with 900 mg/kg of the extract per kg of body weight showed a significant increase in body weight compared to the controls (P=0.014). Neither a significant change in the weight nor in histopathology of liver and kidney were observed in the animals treated with aqueous extract of M. stenopetala compared to those of the controls. Serum glucose level (P=0.034) and serum cholesterol level (P=0.016) decreased significantly after six weeks treatment.

Advances in experimental medicine and biology, 2003

Expression of indoleamine 2,3-dioxygenase (IDO) in epithelium of the endometrium and the cervix i... more Expression of indoleamine 2,3-dioxygenase (IDO) in epithelium of the endometrium and the cervix is not restricted to normal but also present in carcinomatous tissue. The enzyme was found in the majority of cases studied, pioneer cells at the invasion front of the tumors being especially strongly reactive in immunohistology. In addition, also cells in the peritumoral infiltrate of the stroma expressed IDO. Taken together, these findings together with previous data on the immunosuppressive impact of tryptophan depletion suggest IDO-induced suppression of antitumoral immune response in both adenocarcinoma and squamous cell carcinoma of endometrium and cervix. On the other hand, IDO as also known to inhibit tumor cell proliferation by tryptophan depletion.

Ethiopian medical journal, 2014

Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary phase, but ... more Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary phase, but resulting in active tuberculosis (TB) when the immune system is suppressed. Alpha-crystallin (ACR) is one of the bacterial antigens characterized known to be related to shifting of the bacilli from growth to a non-replicating persistent state. To compare the ex-vivo responsiveness of active TB patients, close household contacts and healthy controls to specific Mtb antigens. Antigen-specific interferon-gamma (IFN-g) responses were measured to a 16kDa-alpha crystallin (ACR) antigen along with its peptides and other Mtb antigens (ESAT-6, CFP-10, PPD, TB10.3 and Ag85A) in 39 active TB patients, 23 close household contacts and 25 community controls, using ex-vivo ELISPOT RESULT: The proportion of responders to ACR was 36% in active TB patients (76 +/- 14 spot forming cells), 48% in close household contacts (123 +/- 31 spot forming cells) and 76% in community controls (165 +/- 29 spot forming ...

Journal of Reproductive Immunology, 1996

A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cel... more A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cells from BALB/c mice immunised with human sperm cells. The antibody was determined to be an IgG1. The corresponding antigen is present on the whole surface of ejaculated human spermatozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, cat, dog, sheep, boar, bull, horse). In human male genital organs, immunostaining with GZS-1 is observed on sperm cells in the epididymis and the ductus deferens together with the lining epithelium of those organs. No reactivity of sperm cells or germ cell precursors in the testis has been detected. Functional tests using the antibody show a strong inhibitory effect of human sperm in the hamster egg penetration assay. Furthermore, the GZS-1 antigen is detectable on the surface of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal plasma performed under reducing conditions immunostaining was detected at 21-25, 31, 51-54, and 62 kDa. The reaction with human lymphocytes shows one major band at 62 kDa and additional bands at 31 and 54 kDa. The results suggest that the monoclonal antibody GZS-1 may recognise an antigen which is secreted from the epithelial cells of the epididymis and binds to ejaculated spermatozoa as a sperm coating antigen. This component may be involved in the capacitation of the sperm and the acrosome reaction. Molecules that are expressed both on sperm and on immunocompetent cells may be relevant for the regulation of immunological processes or for the development of the related immunological tolerance of sperm in the female reproductive tract.

Journal of Reproductive Immunology, 1996

A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cel... more A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cells from BALB/c mice immunised with human sperm cells. The antibody was determined to be an IgG1. The corresponding antigen is present on the whole surface of ejaculated human spermatozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, cat, dog, sheep, boar, bull, horse). In human male genital organs, immunostaining with GZS-1 is observed on sperm cells in the epididymis and the ductus deferens together with the lining epithelium of those organs. No reactivity of sperm cells or germ cell precursors in the testis has been detected. Functional tests using the antibody show a strong inhibitory effect of human sperm in the hamster egg penetration assay. Furthermore, the GZS-1 antigen is detectable on the surface of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal plasma performed under reducing conditions immunostaining was detected at 21-25, 31, 51-54, and 62 kDa. The reaction with human lymphocytes shows one major band at 62 kDa and additional bands at 31 and 54 kDa. The results suggest that the monoclonal antibody GZS-1 may recognise an antigen which is secreted from the epithelial cells of the epididymis and binds to ejaculated spermatozoa as a sperm coating antigen. This component may be involved in the capacitation of the sperm and the acrosome reaction. Molecules that are expressed both on sperm and on immunocompetent cells may be relevant for the regulation of immunological processes or for the development of the related immunological tolerance of sperm in the female reproductive tract.

PLoS ONE, 2021

Introduction Human embryo is well protected in the uterus by the embryonic membrane, although ter... more Introduction Human embryo is well protected in the uterus by the embryonic membrane, although teratogens may cause developmental disruptions after maternal exposure to them during early pregnancy. Most of the risk factors contributing to the development of congenital anomalies are uncertain; however, genetic factors, environmental factors and multifactorial inheritance are found to be risk factors. Regardless of their clinical importance, there are little/no studies conducted directly related to predisposing risk factors in southwestern Ethiopia. Objective The study aimed to determine the associated risk factors with congenital anomalies among newborns in southwestern Ethiopia. Methods Case—control study was conducted on newborns and their mothers in six purposively selected hospitals in southwestern Ethiopia from May 2016 to May 2018. Data was collected after evaluation of the neonates for the presence of congenital anomalies using the standard pretested checklist. The data was ana...

Objective: The objective of the present study was to investigate the sub-chronic toxic effects of... more Objective: The objective of the present study was to investigate the sub-chronic toxic effects of butanol fraction of leaves of M. stenopetala on blood parameters of experimental rats. Methods: For this study the rats were divided into three groups. Group I, the control group received distilled water, while the experimental groups: group II received 500 and group III received 1000mg/kg for 63 days by oral gavage. At the end of the experiment blood samples were collected and examined for hematological and biochemical parameters. Results: Treated rats showed no significant changes on hematological and biochemical parameters except blood glucose level (p<0.05)) as compared with the controls. Conclusion: Although, butanol fraction of leaves of M.stenopetala did not produce adverse effects on hematological & biochemical parameters, further detailed studies should be carried out on other vital organs to recommend its therapeutic use.

1Dep’t of Anatomy, College of Health and Medicine Science, Adigrat University 2Department of Anat... more 1Dep’t of Anatomy, College of Health and Medicine Science, Adigrat University 2Department of Anatomy, College of Health Sciences, Addis Ababa University 3Institute of Biomedical science, College of Health Sciences, Mekelle University theamanuel18@gmail.com Summery Solanumnigrum is commonly called black night shade that belongs to Solanaceae (potato) family. It is a fairly common herb or short-lived perennial shrub, found in many wooded areas, as well as disturbed habitats. Various experimental based scientific studies were conducted in order to investigate the efficacy and safety of S. nigrum extract. The scientific investigation from many research findings shows that this plant has various bioactive ingredients such as alkaloids, solanins, saponins, flavonoids, tannins, steroidal glycoalkaloids, steroidal genin and vitamins. These constituents are responsible for diverse activities including: anti-inflammatory, antibacterial, anti-diabetic, anti-fungal, anti-oxidant, hepatoprotecti...

Ethiopian medical journal, 2014

BACKGROUND Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary ... more BACKGROUND Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary phase, but resulting in active tuberculosis (TB) when the immune system is suppressed. Alpha-crystallin (ACR) is one of the bacterial antigens characterized known to be related to shifting of the bacilli from growth to a non-replicating persistent state. OBJECTIVE To compare the ex-vivo responsiveness of active TB patients, close household contacts and healthy controls to specific Mtb antigens. METHODOLOGY Antigen-specific interferon-gamma (IFN-g) responses were measured to a 16kDa-alpha crystallin (ACR) antigen along with its peptides and other Mtb antigens (ESAT-6, CFP-10, PPD, TB10.3 and Ag85A) in 39 active TB patients, 23 close household contacts and 25 community controls, using ex-vivo ELISPOT RESULT: The proportion of responders to ACR was 36% in active TB patients (76 +/- 14 spot forming cells), 48% in close household contacts (123 +/- 31 spot forming cells) and 76% in community c...

International Journal of Sciences: Basic and Applied Research, 2017

Background : Intrauterine development can be considered as normal development as well as abnormal... more Background : Intrauterine development can be considered as normal development as well as abnormal development. Abnormal development commonly called birth defects occur because of interference of normal development from genetic disorders, environmental factors and the combination of both genetic and environment factors during the critical period of embryogenesis. The present study aimed to evaluate the prevalence and patterns of birth defects at birth in Southwestern Ethiopia. Methods : Institutions based cross-sectional study design was used. Six hospitals were selected from the existing hospitals in southwestern Ethiopia purposively based on case load. The study was conducted from September 2011 to December 2015 during which 45,951 deliveries were attained. All records of births that were occurred in the selected hospitals during the study period were identified from medical records, to locate the birth defect records.Results : Twenty-one different birth defects were recorded. Of t...

Ethiopian Journal of Health Development, Sep 22, 2011

Background: Moringa stenopetala and related species are commonly used in folk medicine for variou... more Background: Moringa stenopetala and related species are commonly used in folk medicine for various human diseases such as antimalarial, antihypertensive, antidiabetic and as antispasmodic. Objective: The aim of the study is to evaluate the effects of aqueous extract of M. stenopetala on blood parameters, and histopathology of liver and kidney in experimental mice. Methods: Fresh leaves of M. stenopetala were collected from Arbaminch area, Southwest Ethiopia, in November 2005. The leaves were dried and extracted with water. Three month-old Swiss albino male mice, which were kept under uniform laboratory conditions, were randomly divided into four groups (one group of controls and three experimental). (The control group was orally given 0.5 ml of distilled water, and groups II, III and IV were given the aqueous leaf extract of M. stenopetala using intragastric tube to achieve the required doses of 600, 750 and 900 mg/kg body weight, respectively once a day at 24 hours intervals for six weeks and then sacrificed). Blood sample was collected from each mouse and examined for hematological and biochemical parameters. Liver and kidney were removed, stained and examined for histopathological profiles. The effects of treatment with aqueous extract of M. stenopetala on hematological, biochemical and histopathology features were compared with control group following standard procedures. Results: Mice treated with 900 mg/kg of the extract per kg of body weight showed a significant increase in body weight compared to the controls (P=0.014). Neither a significant change in the weight nor in histopathology of liver and kidney were observed in the animals treated with aqueous extract of M. stenopetala compared to those of the controls. Serum glucose level (P=0.034) and serum cholesterol level (P=0.016) decreased significantly after six weeks treatment.

Ethiopian Journal of Health Development, 2011

Background: Moringa stenopetala and related species are commonly used in folk medicine for variou... more Background: Moringa stenopetala and related species are commonly used in folk medicine for various human diseases such as antimalarial, antihypertensive, antidiabetic and as antispasmodic. Objective: The aim of the study is to evaluate the effects of aqueous extract of M. stenopetala on blood parameters, and histopathology of liver and kidney in experimental mice. Methods: Fresh leaves of M. stenopetala were collected from Arbaminch area, Southwest Ethiopia, in November 2005. The leaves were dried and extracted with water. Three month-old Swiss albino male mice, which were kept under uniform laboratory conditions, were randomly divided into four groups (one group of controls and three experimental). (The control group was orally given 0.5 ml of distilled water, and groups II, III and IV were given the aqueous leaf extract of M. stenopetala using intragastric tube to achieve the required doses of 600, 750 and 900 mg/kg body weight, respectively once a day at 24 hours intervals for six weeks and then sacrificed). Blood sample was collected from each mouse and examined for hematological and biochemical parameters. Liver and kidney were removed, stained and examined for histopathological profiles. The effects of treatment with aqueous extract of M. stenopetala on hematological, biochemical and histopathology features were compared with control group following standard procedures. Results: Mice treated with 900 mg/kg of the extract per kg of body weight showed a significant increase in body weight compared to the controls (P=0.014). Neither a significant change in the weight nor in histopathology of liver and kidney were observed in the animals treated with aqueous extract of M. stenopetala compared to those of the controls. Serum glucose level (P=0.034) and serum cholesterol level (P=0.016) decreased significantly after six weeks treatment.

Advances in experimental medicine and biology, 2003

Expression of indoleamine 2,3-dioxygenase (IDO) in epithelium of the endometrium and the cervix i... more Expression of indoleamine 2,3-dioxygenase (IDO) in epithelium of the endometrium and the cervix is not restricted to normal but also present in carcinomatous tissue. The enzyme was found in the majority of cases studied, pioneer cells at the invasion front of the tumors being especially strongly reactive in immunohistology. In addition, also cells in the peritumoral infiltrate of the stroma expressed IDO. Taken together, these findings together with previous data on the immunosuppressive impact of tryptophan depletion suggest IDO-induced suppression of antitumoral immune response in both adenocarcinoma and squamous cell carcinoma of endometrium and cervix. On the other hand, IDO as also known to inhibit tumor cell proliferation by tryptophan depletion.

Ethiopian medical journal, 2014

Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary phase, but ... more Mycobacterium tuberculosis (Mtb) persists in a state of non-replication or stationary phase, but resulting in active tuberculosis (TB) when the immune system is suppressed. Alpha-crystallin (ACR) is one of the bacterial antigens characterized known to be related to shifting of the bacilli from growth to a non-replicating persistent state. To compare the ex-vivo responsiveness of active TB patients, close household contacts and healthy controls to specific Mtb antigens. Antigen-specific interferon-gamma (IFN-g) responses were measured to a 16kDa-alpha crystallin (ACR) antigen along with its peptides and other Mtb antigens (ESAT-6, CFP-10, PPD, TB10.3 and Ag85A) in 39 active TB patients, 23 close household contacts and 25 community controls, using ex-vivo ELISPOT RESULT: The proportion of responders to ACR was 36% in active TB patients (76 +/- 14 spot forming cells), 48% in close household contacts (123 +/- 31 spot forming cells) and 76% in community controls (165 +/- 29 spot forming ...

Journal of Reproductive Immunology, 1996

A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cel... more A monoclonal antibody (GZS-1) has been generated by fusion of mouse myeloma cells with spleen cells from BALB/c mice immunised with human sperm cells. The antibody was determined to be an IgG1. The corresponding antigen is present on the whole surface of ejaculated human spermatozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, cat, dog, sheep, boar, bull, horse). In human male genital organs, immunostaining with GZS-1 is observed on sperm cells in the epididymis and the ductus deferens together with the lining epithelium of those organs. No reactivity of sperm cells or germ cell precursors in the testis has been detected. Functional tests using the antibody show a strong inhibitory effect of human sperm in the hamster egg penetration assay. Furthermore, the GZS-1 antigen is detectable on the surface of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal plasma performed under reducing conditions immunostaining was detected at 21-25, 31, 51-54, and 62 kDa. The reaction with human lymphocytes shows one major band at 62 kDa and additional bands at 31 and 54 kDa. The results suggest that the monoclonal antibody GZS-1 may recognise an antigen which is secreted from the epithelial cells of the epididymis and binds to ejaculated spermatozoa as a sperm coating antigen. This component may be involved in the capacitation of the sperm and the acrosome reaction. Molecules that are expressed both on sperm and on immunocompetent cells may be relevant for the regulation of immunological processes or for the development of the related immunological tolerance of sperm in the female reproductive tract.