Stability of individual differences in cellular immune responses to acute psychological stress.

To determine the stability of individual differences in cellular immune reactions to acute mental stress, we correlated enumerative and functional lymphocyte responses to an evaluative speech task across two experimental sessions scheduled 2 weeks apart in 30 young men. Relative to pretask baseline measurements, the speech stressor elicited a diminished proliferative response to phytohemagglutinin and concanavalin A, a decrease in circulating CD19 lymphocytes, and an increase in both CD8 and CD56 lymphocytes across the two occasions of testing. Test-retest correlations were significant for the magnitude of change in proliferative response to PHA (r = .50, p < .005) and in numbers of circulating CD8 and CD56 cells (r = .53, and .42, respectively; p's < .02). Concomitant cardiovascular responses also correlated significantly over the two experimental sessions (heart rate: r = .78, p < .0001; systolic and diastolic blood pressure: r = .79 and .48, p < .0001 and .007). These data provide initial evidence that interindividual variability of cellular immune responses to acute psychological stress is moderately reproducible on retesting and may therefore denote a stable dimension of individual differences.