Sperm Autoantigens and Fertilization. I. Eftects of Antisperm Autoantibodies on Rouleaux Formation, Viability, and Acrosome Reaction of Guinea Pig Spermatozoa

Abstract

Fab and IgG were isolated from normal guinea pigs or from the sera of guinea pigs immunized either with their own epididymal spermatozoa or with testis homegenate in complete Freund''s adjuvant. 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 spermotozoa and testis homogenate, but not Fab of normal guinea pig serum, rapidly dispersed sperm rouleaux in a dose-dependent 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 sperm rouleaux head-to-head agglutination and significantly prolonged sperm viability. Most significantly, the acrosome reaction was completely inhibited in the presence of 3.2 .times. 105 antibody molecules (to surface antigens of guinea pig spermatozoa)/spermatozoon. The results strongly implicate guinea pig sperm and testicular cell surface autoantigens in the cell adhesion phenomenon, leading to rouleaux formation and guinea pig sperm surface autoantigens in the induction of capacitation and/or acrosome reaction. Apparently in the guinea pig, sperm rouleaux prevent premature acrosome reaction and preserve sperm viability.