Experimental stress and immunological reactivity: A closer look at perceived uncontrollability

Objective: Although stressor uncontrollability has been shown to suppress immune responses in animals and for human subjects, the results have been inconsistent. We reanalyzed results of our previous study regarding stress-related immune deviation in man, to establish whether perceived uncontrollability of an acute stressor acts as a co-determinant in the observed changes in immunological parameters. Method: Three types of cognitive reactions to an acute interpersonal stressor were assessed: 'motivation,' 'uncontrollability,' and 'guiltiness.' Stress-induced changes in the number of several types of immune cells in peripheral blood and proliferative responses of lymphocytes to antigens and mitogens were assessed. Results: In comparison with control subjects and with subjects perceiving high control over the experimental stress situation, the subject perceiving low control showed a stressor-induced decrease in the number of T helper cells. Reversely, subjects perceiving high control showed an increase in the number of B cells as opposed to the other two groups. The effects of perceived uncontrollability could not be accounted for by mood changes, but they were related to previously experienced life stress. Conclusions: Perceived uncontrollability of an acute stressor can have immuno-modulating effects over and above those of the stressor per se.