Documentation of IgA1 and IgA2 antisperm antibodies within seminal fluid.

Antisperm antibodies of the IgA class, when bound to sperm, impair the sperm's ability to penetrate cervical mucus. IgA proteases offer a potential treatment of autoimmunity to spermatozoa in infertile men by enzymatically degrading immunoglobulins on the sperm surface. As IgA1 but not IgA2 is cleaved by IgA proteases, we determined through use of IgA subclass-specific monoclonal antibodies the presence and relative proportions of antisperm IgA1 and IgA2 in seminal fluid. This ratio varies substantially between men, perhaps reflecting differences in the etiology of autoimmunity to sperm.