Is low titre agglutination seen when testing male sera for antisperm antibodies an immunological phenomenon?

The gelatin agglutination test (GAT) and the tray slide agglutination test (TAT) for antisperm antibodies may yield equivocal titres in a number of cases when sera from infertile men are tested. The question is whether these equivocal titres represent true immunological activity or whether other factors such as beta-spermagglutinins are responsible. The sera from 24 infertile men with moderate or equivocal titres were tested using the TAT after absorption with protein A-producing staphylococci to remove IgG. Only two of the 24 sera showed activity which may have been due to beta-spermagglutinins; the majority of the sera showed no activity following absorption. These results mean that even at low titres the GAT and TAT are detecting immunological agglutination when male sera are tested and by inference that antisperm antibodies in male sera only become clinically significant at higher titres, as it is well known that men may father children in the presence of lower or equivocal serum GAT or TAT titres.