Stress-related impairments in cellular immunity.

The percentages of total T-lymphocytes (OKT-3+), helper T-cells (OKT-4+), and suppressor T-cells (OKT-8+) were significantly lower in blood samples obtained from 40 medical students during examinations, compared to baseline values obtained 6 weeks earlier. In addition, the response of T-lymphocytes to stimulation by phytohemagglutinin and concanavilin A was also significantly lower during examinations, compared to baseline. Self-report data documented significantly greater distress associated with examinations. The data have implications for immunosuppressive disorders and stress-related illnesses.