Lymphocyte subset and cellular immune responses to a brief experimental stressor.

To evaluate effects of acute mental stress on aspects of cellular immunity, lymphocyte populations and phytohemagglutinin (PHA)-stimulated T-cell mitogenesis were measured in 33 healthy young men, both before and immediately following subjects' performance of a frustrating, 21-minute laboratory task (Stroop test). Relative to baseline evaluations, post-task measurements showed a significant reduction in mitogenesis and alterations in various circulating lymphocyte populations; the latter included a diminished T-helper/T-suppressor cell ratio and an elevation in the number of natural killer cells. Eleven subjects assigned to a control (unstressed) condition exhibited no changes in lymphocyte populations, but did show an increase in T-cell proliferation, compared with pretask measurements.