Increased natural killer-cell mobilization and cytotoxicity during maritalconflict

Natural killer (NK) cells are reproducibly mobilized into the circulation i n response to intense physical exercise or acute psychological stress, and altered expression of adhesion molecules potentially contributes to NK-cell mobilization. Studies of leukocyte mobilization during acute stress have u sed psychological stressors which facilitate tight experimental control bur have limited applicability to everyday life. We therefore used a laborator y model of marital conflict as an experientially meaningful acute stressor to elucidate relationships among conflict, cardiovascular reactivity, and a ltered leukocyte phenotype and function. Forty-one ethnically diverse, nond istressed, healthy married couples were asked to discuss a specific problem in their marriage for 15 min. Blood pressure and heart rate were measured before, during, and after the discussion, and blood was remotely drawn at t he same time points to quantify numbers of specific leukocyte subsets, NK-c ell adhesion molecule expression, and NK cytotoxicity. Couples responded to the conflict task with cardiovascular reactivity; increases in the percent ages of circulating NK cells and CD8(+) T cells and decreases in the percen tage of circulating CD4(+) T cells; decreases in the percentage of NK cells that express L-selectin; and increases in NK-cell cytotoxicity without a c ommensurate increase in per-cell cytotoxicity. Rapid downregulation or shed ding of L-selectin (CD62L) from NK cells did not contribute to their mobili zation during conflict. Instead. CD62L(-) NK cells were mobilized while CD6 2L(+) NK cells were selectively retained in the vascular marginating pool a nd/or in extravascular tissue. From a broader perspective, the data support the hypothesis that altered trafficking of specific leukocyte subsets is a n integral component of the fight-or-night response to an acute stressor. ( C) 2000 Academic Press.