The Effects of Stress on Natural Killer Cell Activity in Healthy Men1

Abstract

Several studies have shown that exposure to acute laboratory stressors produces an immediate change in immune function. We examined the effects of a mild laboratory stressor on natural killer (NK) cell cytotoxicity and on psychological and cardiovascular measures in 24 adult males. Subjects in the experimental condition worked on the Stroop task without interference for 30 min with blood samples drawn at baseline, 10, 20, and 30 rnin into the task, and 40 rnin after completing the task. The 30-min stressor produced increases in self-reported stress and tension, and in SBP, DBP, and HR. It was also associated with a decrease in NK cell cytotoxicity 40 min after the stressor. Results are discussed in relation to the effects of mild and intense stressors and future research implications.

Time course of natural killer cell activity and lymphocyte proliferation in response to two acute stressors in healthy men.

“…Consistent with previous studies (L. Cohen et al, 1993;Manuck et al, 1991;Zakowski et al, 1992), we found some relationships between cardiovascular measures during the task and immune responses. This relationship was positive for NK cell activity, with greater increases in HR and DBF in the first 2 min of the stressor predicting greater increases in NK cell activity during the stressor.…”

“…The decrease in activity below baseline at the end of the present experiment was not significant, possibly because we did not continue measurement long enough. Studies reporting a decrease in NK cell activity have observed this decrease at more distal time points than the ones we measured (L. Cohen et al, 1993;Sieber et al, 1992). Had we measured NK cell activity at 30-60 min after stressor termination, we might have observed decreased activity.…”

“…These reductions persisted 24 and 72 hr after the second exposure. L. Cohen, Delahanty, Schmitz, Jenkins, and Baum (1993) also observed decreases in NK activity 40 min after completion of a 30-min Stroop stressor. However, Naliboff et al (1991) observed significant increases in NK cell activity in young women immediately after a 12-min mental arithmetic stressor (differences were not evident among older women), and Knapp et al (1992) reported a weak but nonsignificant increase in NK cell activity immediately after a 40-min negative emotion elicitation.…”

“…A negative relationship was found between HR and proliferation to Con A, with greater increases in HR predicting greater decreases in proliferation during the stressor. L. Cohen et al (1993) found a relationship between heightened cardiovascular reactivity and a more distal decrease in NK cell activity. Again, although these results seem contradictory, they are consistent with those of studies that have shown that in vivo administration of epinephrine to humans is associated with an immediate increase in NK cell activity, followed by a subsequent decrease (Kappel et al, 1991;Tonnesen, Christensen, & Brinklov, 1987).…”

Time-of-day effects on response of natural killer cells to acute stress in men and women.

“…Number of NK cells (CD56+ cells) did not change throughout the experiment. Decreased NK activity (cell numbers were not measured) has also been noted 40 min after the end of a 30-min Stroop task (Cohen et al, 1993). However, a number of studies have found increases in number and activity of NK cells during and following exposure to a Douglas L. Delahanty, Department of Psychology, Kent State University; Taiping Wang, Craig Maravich, Michael Forlenza, and Andrew Baum, Department of Psychology, University of Pittsburgh.…”