Psychobiological factors related to human natural killer cell activity and hormonal modulation of NK cells in vitro.

The present report investigated whether percentages of circulating natural killer (NK) cells and NK cell activity (NKCA) are associated with psychological variables. Subjects (n = 95) were selected, based on a combination of low or high scores on questionnaires on daily hassles and self-reported symptoms, to create four extreme groups. NK cell percentages were different between two of the four groups, only when the analysis was not controlled for gender, life style and endocrine parameters. No evidence was found for a relationship between group membership and NKCA. NKCA, however, was found to differ between men and women and to be associated with percentages of NK cells and intracellular levels of cAMP. Furthermore, the hypothesis was tested, that hormone-induced changes in NKCA in vitro are dependent on the individual's current stress profile. To investigate this issue, NKCA was measured after cells had been incubated with hydrocortisone (10(-6) or 10(-7) M) or the beta-adrenergic agonist isoprenaline (10(-5) or 10(-7) M) in vitro. Changes in NKCA were found to be related to plasma adrenaline levels, but no evidence was found for involvement of psychological variables. It is concluded that, in the current setting, there is no association between the combination of scores on the two psychological questionnaires, and NKCA or hormone-induced changes therein.