Sperm antibodies in serum and seminal plasma

The relation between sperm antibodies (agglutinins and IF-antibodies) in serum and seminal plasma was studied in three selected groups of male partners in infertile couples with respect to specificity, concentrations and immunoglobulin classes. Agglutinins were found in seminal plasma only when they were also present in serum, but there was no strict correlation between the titres in seminal plasma and serum although serum titres were always the higher ones. However, in cases with tail-to-tail agglutinins a difference of more than 2 fourfold steps between the titres was never found; spontaneous agglutination in the ejaculate generally occurred when the seminal plasma titre was 64 or more, and in 6 patients with high seminal plasma titres IgA was detected in the midpiece region of ejaculated spermatozoa. In contrast, head-to-head agglutinins were found in seminal plasma in only one of 3 patients with these agglutinins in serum, and only in a low titre. Absorption of IgG of IgG with protein-A-producing Staphylococcus aureus showed that tail-to-tail agglutinins in serum were IgG antibodies, whereas they could be characterized as "non-IgA-in seminal plasma, suggesting a local production of these antibodies. IF-antibodies were rarely found in seminal plasma and seemed to be of little significance in relation to infertility in men.