Impairment of immune function after cessation of long-term chronic stress.
A pronounced impairment of mitogen-induced proliferation of splenic lymphocytes was observed in Fischer-344 male rats 1 month after termination of exposure of the animals to stress. The stress model used in these experiments was random schedules of a signaled, escapable electric foot-shock stress for 2-4 h/day over a period of 6 months. The magnitude of the observed immunosuppression correlated positively with the total, cumulative stress exposure received by the animals. The effect was not secondary to changes in the percentage of splenic T lymphocytes in stressed, compared to control rats. Also, at the time of sacrifice, plasma levels of corticosterone were comparable in experimental and control animals. Therefore, the immunosuppression observed 1 month after the last stress session cannot be attributed to pituitary-adrenocortical hyperactivity, at the time of sacrifice. These results provide the first evidence that stress-induced immunosuppression is not restricted to the period of exposure to the stress. This finding may contribute to a better understanding of the suggested association between stressful life events and increased susceptibility to disease in humans.
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005434:Flow Cytometry / Q000379:methods; D007108:Immune Tolerance; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D010835:Phytohemagglutinins / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013154:Spleen / Q000166:cytology; D013312:Stress, Physiological / Q000276:immunology*; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*; D013997:Time Factors
D010835:Phytohemagglutinins; D003208:Concanavalin A