The interfering effect of human IgG antisperm antibodies on human sperm penetration of zona-free hamster eggs.

A liquid-phase radioimmunoassay was used to quantitate sperm-associated IgG in a population of patients with unexplained infertility. Plasma IgG antisperm antibody activity was identified in a subpopulation of these patients. Using the human sperm/hamster egg assay, a unique functional test of human sperm penetrating capacity, we identified a subset of these positive patients whose plasma significantly and reproducibly inhibited penetration. This study implies that antigen-antibody reactions may prevent sperm responses that are critical to sperm-egg fusion.