Immunofluorescent studies on human spermatozoa. II. Characterization of spermatozoal antigens and their occurrence in spermatozoa from the male partners of infertile couples

The object of this study was to elucidate properties, organ specificity, and the occurrence in individual spermatozoa of the four antigens which can be identified in methanol-fixed human spermatozoa by the indirect immunofluorescence technique using human antisera, i.e. the antigen in the front part of the acrosome, in the equatorial segment, in the postnuclear region, and in the main tail piece.

With unfixed spermatozoa the reactions were weak and often uncharacteristic. After fixation with ethanol and acetone all four antigens were preserved, while after fixation with formalin the postnuclear antigen was not demonstrable. The antigens in the equatorial segment and in the postnuclear region were destroyed at 60°C and those in the front part of the acrosome and in the tail at 80°C. After the spermatozoa had been treated with trypsin the reaction with the three antigens in the head disappeared. However, with rabbit antiserum to human spermatozoa fluorescence could be induced even after heating the spermatozoa to 100°C or treating them with trypsin.

Absorption of the human antisera with seminal plasma, human milk, liver, kidney, and adrenal extract disclosed an antigenic relationship between the postnuclear antigen and seminal plasma as well as between the antigen in the front part of the acrosome and adrenal extract.

By means of known antisera the occurrence of acrosome antigens in the individual spermatozoa was investigated in ejaculates from seventy-six male partners of infertile couples. In ejaculates with a normal concentration of spermatozoa the antigens were generally demonstrable in at least 50% of the spermatozoa, whereas samples with a low concentration showed a marked variation, the staining percentages ranging from 0 to 90%.