A variety of psychosocial factors have been shown to influence immunological responses in laboratory primates. The present investigation examined the effects of social housing condition on cell-mediated immune responses, comparing rhesus macaques (Macaca mulatta) in three housing conditions (single, pair, and group). Subjects included 12 adults of both sexes in each housing condition (N=36). The Group treatment was made up of stable social groups of one male, 4-7 females and their most recent offspring. Multiple blood samples (at 0, 4, 8, and 12 months of age) were collected for immunological analyses, including lymphocyte subsets, lymphocyte proliferation to pathogens and nonspecific mitogens, natural killer cell activity, and cytokine production. CD4+:CD8+ ratios differed significantly across housing conditions and singly caged subjects had significantly lower CD4+:CD8+ after 4-months than did socially housed (pair and group) subjects. CD4+:CD8+ ratios were positively correlated within subjects, suggesting a trait-like aspect to this parameter. Lymphocyte proliferation responses to 4 gastrointestinal pathogens (Escherichia coli, Salmonella typhimurium, Shigella flexneri, Campylobacter jejuni) differed across housing conditions (at least at the 0.08 level), as did proliferation responses to Staphylococcus A, and the production of cytokines (IFN- gamma , IL-2 and IL-10). Proliferation responses of singly caged monkeys did not differ from socially housed monkeys and the highest levels of both IFN- gamma and IL-10 were produced by group housed subjects. The data demonstrate that social housing condition affects immune responses. While not unidirectional, these effects generally suggest enhanced immune responses for socially housed animals. Since rhesus monkeys live socially in nature, and the immune responses of singly housed animals differed from those housed socially, there is considerable motivation and justification for suggesting that the use of singly housed rhesus macaques may complicate interpretations of normal immunological responses. This may have important implications for the management, treatment, and selection of primate subjects for immunological studies.
|Publication Title||Applied Animal Behaviour Science|
|Author Address||Department of Veterinary Sciences, University of Texas, M.D. Anderson Cancer Center, Rt. 2, Box 151-B1, Bastrop, TX 78602, USA.|
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