Enumerative immune changes following acute stress: effect of the menstrual cycle

This study examined enumerative immune and catecholamine measures and their response to a speaking stressor in 20 healthy women during two phases of the menstrual cycle. Subjects were studied at the same time of day on two separate occasions approximately 6 weeks apart, once during the follicular phase (Days 7-10 following menses) and once during the luteal phase (Days 7-10 following the LH surge) of the cycle. The stressor was associated with significantly increased CD8 cells (p < .001). NK cells (CD16, CD56, and CD57, p < .001), and plasma norepinephrine (p < .01) and decreased CD4/CD8 ratio (p < .001). There were no significant main effects for menstrual phase nor significant interactions for menstrual phase by task for any dependent variable. Baseline and stress test-retest correlation coefficients were similar to those reported in the literature for men and indicate a moderate test-retest reliability. Change score test-retest correlation coefficients were consistently smaller and only CD56 (r = .49) and the CD4/CD8 ratio (r = .55) correlated significantly. The findings suggest that the changes in reproductive hormones associated with the menstrual cycle have no appreciable effect on lymphocyte numbers or their response to acute stress. Given estrogen's long-term duration of action, it may be that their menstrual cycle does not afford an adequate window of time to scrutinize reproductive hormone effects on the immune functioning.