Antigenicity of sperm: immunization of rabbits with pig's sperm

The state of antibody production and the tissue and species specificities together with the sperm immobilizing action of various antibodies in rabbits were examined after immunization with pig's sperm. Before the immunization, the titers of various antibodies against pig's sperm seemed to be generally higher in male than in virgin female, but they became no obvious difference between the two sexes after the immunization. Precipitins of the sera obtained by immunizing rabbits with pig's spermatozoa extract reacted not only with pig's spermatozoa extract but also with heterologous spermatozoa extract to moderate degree, but no cross reaction with pig's serum or heterologous serum was visible, and it was not associated with the sperm immobilization. The sperm-microagglutinin obtained by immunization with pig's spermatozoa showed strong species specificity and moderate tissue specificity. The motility of the sperm was not obviously inhibited by sperm agglutinin. The titer of it was the highest among the immune antibodies, but there are problems in detecting the specific antibody because spontaneous sperm agglutination is common and it is difficult to determine whether the agglutination is due to antisperm antibody or to a nonspecific factor. The evidence that strong tissue and species specific sperm-immobilizing antibody could be produced by immunizing rabbits with heterologous pig's sperm in both sexes gives us the confidence that sperm immobilization by immunization of both sexes with homologous sperm could contribute to human population control in the future.