Stress decreases lymphocyte cytolytic activity in the young monkey even after blockade of steroid and opiate hormone receptors.

Lymphocyte cytolytic responses were assessed in 75 infant squirrel monkeys to investigate the influence of psychosocial disturbance on immunity. Four studies evaluated alterations in lytic activity during social separations from the mother lasting for 1-7 days. Lytic responses against target cells were markedly decreased during the first day of separation, and then gradually returned toward baseline levels. Although associated with a general lymphocytopenia in vivo, lower lysis was not mediated specifically by inclusion of fewer Leu11b+ cells in the in vitro assay. Multiple physiological processes probably converge to mediate the decrease in lysis. Treatment of the infant with RU486 to block corticosteroid hormone receptors or with naltrexone to antagonize opiate hormone action did not prevent the decrease in lytic responses from occurring. This research demonstrates that psychological disturbance can significantly impact immunity, but the recovery of normal functioning by 1 week also reveals the resiliency of the immune system, paralleling the time course of the infant's behavioral adaptation to this challenge.