Sperm autoantigens and fertilization. I. Effects of antisperm autoantibodies on Rouleaux formation, viability, and acrosome reaction of guinea pig spermatozoa.

Abstract

Fab and IgG were isolated from the sera of 1) guinea pigs immunized with their own epididymal spermatozoa or testis homogenate in complete Freund’s adjuvant, or 2) normal guinea pigs. Their effects on rouleaux formation, the viability, and the acrosomal reaction of guinea pig epididymal spermatozoa were studied in vitro. Monovalent (Fab) antibodies to epididymal spermatozoa and testis homogenate, but not Fab of normal guinea pig serum, rapidly dispersed sperm rouleaux in a dosedependent and time-dependent manner. The effect was reversed by the addition of epididymal spermatozoa and was prevented if the Fab antibody was previously absorbed with guinea pig spermatozoa but not with guinea pig spleen cells or Mycobacterium tuberculosis. Compared with spermatozoa in Fab of normal guinea pig serum, the dispersed spermatozoa were less viable, and the rate of acrosomal reaction was significantly reduced. Contrary to expectation, bivalent (IgG) antibody to epididymal spermatozoa did not agglutinate sperm rouleaux. It prevented head-to-head agglutination of sperm rouleaux and significantly prolonged sperm viability. Most significantly, the acrosome reaction was completely inhibited in the presence of 3.2 X 10’ antibody molecules (to surface antigens of guinea pig spermatozoa) per spermatozoon. The results strongly implicate 1) guinea pig sperm and testicular cell surface autoantigens in the cell adhesion phenomenon leading to rouleaux formation, and 2) guinea pig sperm surface autoantigens in the induction of capacitation and/or acrosome reaction. We further suggest that, in the guinea pig; sperm rouleaux prevent premature acrosome reaction