Immune Response to Immunization with Sperm Antigens in the Macaque Oviduct1

The oviduct of most mammalian species is the site where spermatozoa first encounter the oocyte and the process of fertilization is initiated. It should therefore be considered an important focus of study for the development of an effective gamete immunocontraceptive with the goal of immunologically interfering with spermatozoon function. The study reported here used the cynomolgus macaque as a nonhuman primate model in which to analyze the serum and oviductal fluid immune response to immunization with the human sperm protein Sp17 and synthetic peptides derived from Sp17. Human and macaque Sp17 were shown to share a very high degree of identity (96.7%), confirming this species as a suitable model in which to study the antibody response and recognition of spermatozoa. The oviductal fluid antibody titer varied with respect to serum titer both over time for individual monkeys and between different monkeys. In all cases, however, the antibody response was restricted solely to the immunoglobulin G class. Finally, both serum and oviductal fluid antibodies were directed against identical Sp17 B-cell epitopes and both recognized native macaque Sp17 in spermatozoa.