Early social deprivation in nonhuman primates: Long-term effects on survival and cell-mediated immunity

Background: Early differential social experience of non-human primates has resulted in long-term alterations in behavior and neurobiology. Although br ief maternal separation has been associated with changes in immune status, the long-term effects on survival and immune function of prolonged early so cial deprivation are unknown. Methods: Survival rates were examined in rhesus monkeys, half of which had been socially deprived during their first year of life. Repeated measures o f immune status were tested in surviving monkeys (18-24 years old). Periphe ral blood T, B, and natural killer lymphocytes, macrophages, and monocytes were measured by flow cytometry. Function al cellular immune activity measu res included T-cell proliferative responses to mitogens (concanavalin and p hytohemagglutinin), T-cell memory response to tetanus toroid antigen, T-cel l-dependent B-cell proliferative responses to mitogen (PWM) and natural kil ler cell cytotoxic activity, Results: Despite identical environments following isolation, early social d eprivation resulted in a significantly decreased survival rate, males being particularly vulnerable to early death, Early social deprivation was assoc iated with a decrease in the ratio of helper to suppressor T cells, and a s ignificant increase in natural killer cell number and in natural killer cel l activity in the surviving monkeys. No differences in T- or B-lymphocyte p roliferation following mitogen or tetanus toxoid antigen stimulation were o bserved, Conclusions: Prolonged early social deprivation of nonhuman primates profou ndly affected mortality and resulted in lifelong effects on cell-mediated i mmune status. (C) 2000 Society of Biological Psychiatry.