THE MONOCLONAL-ANTIBODY GZS-1 DETECTS A MATURATION-ASSOCIATED ANTIGENOF HUMAN SPERMATOZOA THAT IS ALSO PRESENT ON THE SURFACE OF HUMAN MONONUCLEAR BLOOD-CELLS

A monoclonal antibody (GZS-1) has been generated by fusion of mouse my eloma cells with spleen cells from BALB/c mice immunised with human sp erm cells. The antibody was determined to be an IgG(1). The correspond ing antigen is present on the whole surface of ejaculated human sperma tozoa. It is not detectable on spermatozoa of other mammalian species (rabbit, car, dog, sheep, boar, bull, horse). In human male genital or gans, immuno-staining with GZS-1 is observed on sperm cells in the epi didymis 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 sho w a strong inhibitory effect on human sperm in the hamster egg penetra tion assay. Furthermore, the GZS-1 antigen is detectable on the surfac e of human lymphocytes and monocytes by immunogold electron microscopy and FACS analysis. By Western blotting of human sperm and seminal pla sma performed under reducing conditions immunostaining was detected at 21-25, 31, 51-54, and 62 kDa. The reaction with human lymphocytes sho ws 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 a ntigen which is secreted from the epithelial cells of the epididymis a nd binds to ejaculated spermatozoa as a sperm coating antigen. This co mponent may be involved in the capacitation of the sperm and the acros ome reaction. Molecules that are expressed both on sperm and on immuno competent cells may be relevant for the regulation of immunological pr ocesses or for the development of the related immunological tolerance of sperm in the female reproductive tract.