Infertility in female rabbits immunized with lactate dehydrogenase X

Immunization of female rabbits with the sperm-specific lactate dehydrogenase (LDH-X) resulted in a highly significant reduction of pregnancies compared to nonimmunized controls. This is the first demonstration of immunosuppression of fertility by a crystalline protein shown to be strictly homogeneous by ultracentrifugation, polyacrylamide gel electrophoresis, immunodiffusion, and micro complement fixation.