Acrosin antibodies and infertility. I. Detection of antibodies towards proacrosin/acrosin in women consulting for infertility and evaluation of their effects upon the sperm protease activities.

OBJECTIVE To detect the presence of antibodies to the proacrosin/acrosin system and to evaluate their effect on the sperm acrosomal protein activities in women consulting for infertility. DESIGN Retrospective study. SETTING Basic research laboratory. PATIENT(S) Recombinant proteins derived from human proacrosin (Rec-40, Rec-30, Rec-20, Rec-10) and recombinant human zona pellucida (ZP) glycoprotein A( *) (rec-hZPA). INTERVENTION(S) Development of an ELISA-Acro to test for antiacrosin antibodies using Rec-40 and truncated acrosin proteins as antigens. MAIN OUTCOME MEASURE(S) Evaluation of: 1) the presence of antiacrosin antibodies; 2) the protein regions recognized by the antibodies; 3) the relationship between antiacrosin antibodies and surface antisperm antibodies (ASA) identified by the immunobead binding test (IBT); and 4) the effect of antiacrosin antibodies upon proacrosin/acrosin binding activity to ZPA and acrosin amidase activity. RESULT(S) Antiacrosin antibodies were detected in sera from 34 of 179 women (19%). Detection of ASA by the IBT resulted in a similar incidence (36 of 179, 20%), although only six of them showed correspondence between both assays; five of these six sera were IBT-positive IgGs to the sperm head. Antiacrosin antibodies directed toward different protein regions inhibited proacrosin binding activity to rec-hZPA as well as its activation and acrosin amidase activity in protein sperm extracts. CONCLUSION(S) Antiacrosin antibodies are present in sera of women consulting for infertility in both IBT-positive and IBT-negative samples, and they affect proacrosin/acrosin activities.