Sera from simian immunodeficiency virus-infected rhesus macaques inhibit lymphocyte proliferation

Rhesus macaque monkeys infected with the simian immunodeficiency virus (SIV) develop a syndrome mimicking acquired immunodeficiency syndrome (AIDS) in humans. We had demonstrated previously that sera from individuals infected with human immunodeficiency virus (HIV) inhibit the proliferation of lymphocytes from healthy noninfected subjects and that this phenomenon was associated with the development of clinical AIDS. Thus, we sought to determine whether sera from SIV-infected monkeys would also inhibit lymphocytes from healthy humans and SIV-negative rhesus monkeys. Sera from SIV-infected monkeys were compared with sera from uninfected animals and cultured with cells from healthy human volunteers or SIV-negative monkeys in the presence or absence of phytohemagglutinin (PHA). Cell proliferation was determined by measuring the incorporation of radiolabeled thymidine into cellular DNA. Sera from SIV-infected monkeys suppressed the proliferation of human and non-human primate lymphocytes. This activity appears to be similar to that described for sera from HIV-1-infected humans. Therefore, rhesus macaques infected with SIV provide a model for the study of serum inhibitory factors previously reported in AIDS patients.