EFFECTS OF DOMINANCE STATUS AND ENVIRONMENTAL ENRICHMENT ON CELL-MEDIATED-IMMUNITY IN RHESUS MACAQUES

Psychosocial variables have been shown to affect cell-mediated immune responses in captive macaques. To explore whether one major (social do minance) and/or one minor (environmental enrichment) psychosocial vari able affected immune responses in female rhesus monkeys, cell-mediated immune responses were compared in six monkeys that were the highest r anking and 12 monkeys that were middle ranking in their respective soc ial groups. All subjects were 5- and 6-year-old rhesus living in stabl e unimale-multifemale groups, and were matched on social history, pari ty, weight, and health characteristics. Highest-ranking females had si gnificantly lower mitogen-induced proliferation responses to lipopolys accharide and pokeweed mitogen and higher natural killer cell activity , CD4(+) lymphocyte counts, and CD8(+) lymphocyte counts than did midd le-ranking females. These data demonstrate that dominance rank, an imp ortant psychosocial factor, affects immune response in a stable social setting. One-half of the subjects (three highest-ranking and six midd le-ranking) received a variety of environmental enhancements between t he ages of 1 and 4 years (the enriched group), while the other nine su bjects did not (the control group). No differences between enriched an d control groups reached statistical significance, but some interestin g trends appeared, tentatively suggesting that a minor psychosocial ma nipulation, inanimate enrichment, may subtly affect cell-mediated immu ne responses. The relationship between psychosocial factors and cellul ar immune function may have important implications for disease progres sion and far the management, treatment. and selection of primate subje cts for studies in which immunological variables are of interest. (C) 1998 Elsevier Science B.V.