The expression of genomic progesterone receptor in human ejaculated spermatozoa was investigated. Spermatozoa from 10 fertile donors who exhibited normal semen parameters were analysed. Indirect immunofluorescence and an enzyme immunoassay using monoclonal antibodies against genomic progesterone receptor were used. Different types of spermatozoa were studied: fresh, post-swim-up (migrated), capacitated and post-artificial induction of the acrosome reaction by calcium ionophore A23187. Progestin receptor-rich T47D human breast cancer cells were used as a positive control, and progestin receptor-poor MDA-MB-231 human breast carcinoma cells were used as a negative control. Genomic progesterone receptor was not detected in fresh, migrated, capacitated and post-acrosome reaction induction human spermatozoa and MDA-MB-231 cells by either indirect immunofluorescence or enzyme immunoassay. However, in T47D cells a mean concentration of 1043.2 +/- 125.2 fmol genomic progesterone receptor/mg protein was observed by enzyme immunoassay, and indirect immunofluorescence results were positive using both flow cytometry and fluorescence microscopy. These findings suggest that the effect of progesterone on human spermatozoa is not mediated by genomic progesterone receptor.
Using flow cytometry, we studied the expression of the CD4 antigen within the different cells present in human ejaculate, both in spermatozoa and round cells. In all, 20 samples of semen were obtained from fertile males; in 11 of these, we detected the presence of leukocytes, using the peroxidase test. Swim-up was performed for the analysis of the spermatozoa. From our results it may be concluded that there is no expression of the CD4 antigen on the surface of human spermatozoa or on CD45- ejaculate cells (epithelial and germinal cells). However, we did detect the presence of the CD4 antigen on the surface of the leukocyte cells (CD45+). A better characterization of these CD45+ cells made it apparent that the CD4+ cells of ejaculate are composed of T lymphocytes (helper/inducer T lymphocytes) and monocytes. Thus we may conclude that human spermatozoa do not express the CD4 antigen, the cell surface receptor for human immunodeficiency virus. However, we did detect CD4+ T lymphocytes and CD4+ monocytes in semen.
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