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^**Also named as ZP2 (Symbol report: ZP2. Human Genome Organizaion [HUGO]. Gene Nomenclature Committee, April 25, 2005, http://www.gene.ucl.ac.uk/nomenclature/data/get_data.php?hgnc_id=13188, September 6, 2005.) (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.