ADRENERGIC-BLOCKADE AMELIORATES CELLULAR IMMUNE-RESPONSES TO MENTAL STRESS IN HUMANS

This study evaluated the sympathoadrenal modulation of behaviorally ev oked immune responses by administration of a nonselective adrenoceptor antagonist (labetalol) to subjects exposed to mental stress. In a 2 X 2 factorial design, subjects were assigned to a labetalol or saline c ondition and, within each condition, were exposed either to acute labo ratory stress or no stress (control), Lymphocyte subsets, natural kill er (NK) cell cytotoxicity, and T cell proliferation to phytohemaggluti nin and concanavalin A were assessed pre-experimentally, at baseline a fter infusion and after 18 minutes of mental stress (or rest). By comp arison with the other three conditions, the saline-stress group showed a greater peripheral NK cell number and cytotoxicity, lower mitogenic response to phytohemagglutinin and concanavalin A, and diminished rat io of CD4:CD8 cells after the stressor. As predicted, immune responses did not differ among the remaining groups (labetalol-stress, saline-r est, labetalol-rest), Group differences in NK cell cytotoxicity were n ot significant after controlling for differences in NK cell numbers. T hese findings demonstrate that the occurrence of certain immunologic r esponses to acute psychological stress are dependent on concomitant ac tivation of the sympathetic nervous system.