Differential effects of active and passive laboratory stressors on immune function in healthy men

The immunomodulatory effects of acute laboratory stressors were examined by comparing active and passive stressors in a between-subjects design. Healthy male volunteers (N = 67) were recruited and randomly assigned to an active, passive, or no stressor condition. Subjects were exposed to either the Stroop and mental arithmetic tasks (active). two surgery films (passive). or two nature films (no stress). Cardiovascular reactivity, plasma catecholamines and cortisol. and self-reported distress were measured pre-task and post-task. Lymphocyte proliferation to concanavalin A (Con A). pokeweed mitogen (PWM), and phytohemagglutinin was assessed a1 baseline, after the first task, after the second task, and 30 min later. Lymphocyte proliferation lo Con A and PWM was significantly reduced in response to the stressors. Different response patterns emerged, depending on the type of stressor and the mitogen used. Changes in lymphocyte proliferation were significantly associated with cardiovascular reactivity during the tasks. Results are discussed in terms of potency of the stressors and mechanisms underlying passive versus active laboratory tasks. Implications for future research are addressed.