ABSTRACT
Blood samples were obtained from 42 medical students during a period of moderate academic stress, immediately before a final examination and after their summer vacations. T lymphocyte proliferation in response to 5, 10 and 20 mg/ml phytohemagglutinin was measured by the incorporation of 3H-thymidine, and plasma cortisol was measured by RIA. Results: T lymphocyte stimulation index in response to all phytohemagglutinin concentrations was significatively lower in the period before examination than in the other two periods.There were no differences in the index between the period of moderate stress and after summer vacations. Plasma cortisol levels were 15.6 ñ 4.3, 18.6 ñ 5.8 and 16.7 ñ 5.1 mg/dl during the periods of moderate stress, before the examination and after vacations, respectively (p < 0.05 for the difference between examination and the other two periods). Conclusions: There is a decrease in lymphocyte proliferation and an increase in cortisol levels during a period of acute academic stress in medical students, suggesting that, the exposure of healthy subjects to common stress ful stimuli, may affect their immunocompetance