Immunofluorescent studies on human spermatozoa. I. The detection of different spermatozoal antibodies and their occurrence in normal and infertile women.

Sera from children, blood donors, pregnant women and women from infertile couples were tested by the indirect immunofluorescent technique on methanol-fixed human spermatozoa. Four different staining patterns were observed: (1) Staining of the acrosome: a homogeneous fluorescence usually covering the entire acrosome and thus including the equatorial segment, but with some sera only the front part of the acrosome was stained. (2) Staining of the equatorial segment: a narrow well-demarcated fluorescent band across the head at the equator. (3) Staining of the postnuclear area: two fluorescent bands on the posterior third of the head, forming a bowl-like figure closely corresponding to the localization of the postnuclear cap. (4) Staining of the tail: usually only involving the main tail piece. Combinations of these staining patterns were often seen. Staining of the postnuclear area was found with only three out of the 330 sera tested, whereas the other antibodies were frequently present in low titres (titre ≤ 4) in all groups studied. On the other hand, titres ≥ 16 were found significantly more frequent among women from infertile couples than in any of the control groups, and in the further analysis of the infertile group the antibody levels appeared to be significantly higher among women with unexplained infertility than among those in whom the infertility could be explained.