IN-VIVO INHIBITION OF CELL-MEDIATED AND HUMORAL IMMUNE-RESPONSES TO CELLULAR ANTIGENS BY SV-IV, A MAJOR PROTEIN SECRETED FROM THE RAT SEMINAL-VESICLE EPITHELIUM

Microgram amounts of protein SV-IV, a major secretory protein produced by adult rat seminal vesicle epithelium, markedly decrease the mouse humoral immune response to cellular xenogeneic or allogeneic antigens (sheep red blood cells (SRBC) or mouse epididymal spermatozoa). The si gnificant reduction in the total number of splenocytes and their main cell subsets in SRBC-immunized mice, the dramatic decrease in the numb er of Ia(+) splenic T cells and the marked inhibition of splenocyte ab ility to respond in vitro to polyclonal mitogen stimuli suggest that t he macrophage accessory cells are the primary target of the SV-IV immu nosuppressive activity in vivo. Moreover, the infection of SV-IV-treat ed mice with Salmonella typhimurium produced an increased mortality of the experimental animals associated with a marked decrease of the pha gocytic and intracellular killing activities of their peritoneal macro phages.