EFFECTS OF SOCIAL REORGANIZATION ON CELLULAR-IMMUNITY IN MALE CYNOMOLGUS MONKEYS

Exposure to acute stressors has been shown to impair cellular immunity in human beings and other animal species. Comparatively little is kno wn, however, about the effects of long-term stressors on immune functi on and how individual behavioral characteristics may mediate differenc es in immune function and clinical disease susceptibility. To determin e the effects of social stress on cellular immunity and reactivation o f a latent herpesvirus, 20 Herpes B virus-positive male cynomolgus mon keys were exposed to four periodic reorganizations of social group mem berships over 5 months. Observations were made to categorize individua ls as high or low in expression of aggressive, fearful, and affiliativ e behaviors. Complete blood counts, lymphocyte proliferation tests, an d natural killer cell cytotoxicity assays were performed immediately b efore and 4 days after reorganizations. Herpesvirus-specific immunoglo bulin G antibody levels were measured, and oral and conjunctival swabs were cultured for virus. Reorganization was associated with increased lymphocyte counts (P = 0.0009) and decreased lymphocyte proliferation in response to phytohemagglutinin (P < 0.005), particularly among mon keys showing high levels of fear (P = 0.0137). High-aggressive monkeys showed lower baseline natural killer cell activity(P = 0.0013) and hi gher lymphocyte counts (P = 0.013) than low-aggressive monkeys. Herpes virus antibody titers decreased over time (P < 0.004) and no positive virus cultures were obtained. Measures of cellular immunity and behavi or were unrelated to virus-specific antibody titers. These results sug gest that repeated exposure to a social stressor alters several measur es of cellular immunity, and that some of these changes may be predict ed by individual differences in agonistic behavior. In contrast to hum an studies, the results suggest that some psychological stressors may not cause reactivation of a common herpesvirus in this species. (C) 19 96 Wiley-Liss, Inc.