Sperm antibodies in men from infertile couples. Analysis of sperm agglutinins and immunofluorescent antibodies in 657 men.

Sera from 657 men from infertile couples were tested for sperm agglutinins and spermatozoal antibodies detectable by the indirect immunofluorescense technique (IFT), and the results were correlated to the clinical examinations of the couples. Sperm agglutinins were found in 6.7%. Spontaneous agglutination of the ejaculated spermatozoa was observed only among these men, most commonly among those with high serum titres. IF-antibodies against the four spermatozoal antigens located beneath the cell membrane occurred in 15.2% of the patients. Antibodies against the front part of the acrosome and the postnuclear cap were mainly IgM. Antibodies against the equatorial segment of the acrosome were predominantly IgG and in a few cases IgA, whereas straining of the main tail piece was caused by IgG antibodies. Considering the clinical fertility status of the couples, sperm agglutinins in high titres (greater than or equal to 10) against the equatorial segment and the main tail piece of the spermatozoa were found significantly more often among men from couples with unexplained infertility than among clinically normal men from couples where the findings in the women could be assumed to cause infertility. These results support the view that sperm agglutinins can cause infertility, whereas the significance of the IF-antibodies is still unclarified as, in some cases, these can be found even in high titres in men with proven fertility. The possible mechanism of autosensitization were evaluated by means of an anamnestic study.