A direct immunofluorescence test for the detection of sperm surface bound antibodies. Comparison with sperm...

A direct immunofluorescence (DIF) test using sperm suspensions and F (ab')2 antisera was carried out on 30 patients with sperm-agglutinating (SA) activity and on 25 negative controls. Its results were related with the occurrence of SA activity in serum and seminal plasma, with the results of the indirect IF test and those of the direct IgG-MAR test. DIF test gave positive results in all patients with significant serum SA activity, even when it was undetectable in seminal plasma, except in 2 cases with serum IF-reactivity for IgM, and negative results in all controls. IgG were involved in IF-reactivity in 88.4% of positive cases and IgA in 42.3%. IgA were always found in association with sustained SA activity in seminal plasma. In these cases the IgG-MAR test might not result strongly positive, in spite of the high titre of SA activity in semen.