Circulating antispermatozoa immunoglobulin G in men after vasectomy.

The sera from ten vasectomized men produced immobilization and agglutination of human spermatozoa and positive passive hemagglutination tests. Immunoglobulin G fractionated from the samples of sera produced similar effects. In these men, it appears that a circulating antibody, immunoglobulin G, was produced against spermatozoa after vasectomy. The sera from 22 men who had not undergone vasectomy did not cause spermatozoa immobilization or agglutination, and produced a negative passive hemagglutination test.