Ultrastructural lesions induced in vitro in guinea-pig spermatozoa by a specific autoantibody (anti-T) and complement

A quantitative ultrastructural study has been carried out on the lesions that are induced in vitro in guinea-pig spermatozoa by the action of auto-antispermatozoa antibodies and complement. The responsibility of three-independent autoantigen-autoantibody systems (S, P and T) has been explored. The only anti-T antibody known to fix complement and to be spermotoxic (T is a membrane-linked autoantigen), caused significant and important lesions, the immunologically specific origin of which was demonstrated. These lesions began a few seconds after complement had been added. The cytoplasmic membrane is first involved, then the acrosomal membranes, and then the acrosomal contents are lysed. The remarkable rapidity of action of complement on the antibody-sensitized target is emphasized. A typical dose-effect curve is obtained with dilutions of anti-T immune sera. Non-C1-fixing anti-S as well as C1-fixing anti-P antibodies (P has been shown to be intra-acrosomal) do not provoke any significant lesions, even in the presence fo complement, as compared to normal and various controls. However, anti-P serum, when added to non-damaging dilutions of anti-T in the presence of complement, was able to provoke significant lesions in the acrosomes. The bearing of these findings on the mechanisms of in vivo lesions is discussed.