The influence of age and pregnancy on immune responses of baboons to mitogens and the baboon endogenous virus

Immune responses to mitogens and baboon endogenous type C virus (BaEV) were assessed in baboons according to age, sex, and at various stages of pregnancy. Generally there were no significant differences noted in the immunologic responses between males and females. However, age and pregnancy had pronounced effects on mitogen responses and specific humoral and cell-mediated immunity (CMI) to BaEV. Lymphocyte responses to mitogens declined with increasing age and were significantly suppressed in the third trimester of pregnancy. Humoral immunity (HI) to BaEV assayed by radioimmunoprecipitation (RIP) was observed in pregnant, but not age-matched nonpregnant, baboons and this reactivity declined with increasing time of pregnancy. In nonpregnant animals, RIP antibodies were only detected in very young (-12 years of age) baboons. CMI as assayed by lymphocyte blastogenesis (LB) and macrophage migration inhibitory factor (MIF) was suppressed during pregnancy. In relation to age LB responses to BaEV did not follow a clear pattern; however, MIF (like RIP) was only found in young (