Effects of experimental psychological stress on T-lymphocytes and NK cells in man: an exploratory study

Experimental subjects (N = 11) were exposed to a mild and potentially uncontrollable interpersonal stress situation. They were asked to solve a difficult puzzle and subsequently to explain their solution to 'another subject', actually a confederate of the researchers. The confederate frustated the subjects' explanation efforts. Care was taken that neither solution nor explanation of the puzzle was successful. The experimental situation induced mild psychological strain as documented by mood changes in the experimental group when compared with the controls. Before, directly after and half an hour after the stress situation blood was drawn, in which percentages of total T-cells, T-helper/inducer cells, T-suppressor/cytotoxic cells and NK cells were determined. In contrast to control subjects (N = 15), experimental subjects showed significant increases of NK cell percentages after the stress period, returning to baseline values after the second rest period. T-helper/inducer cell percentage showed a similar reversed pattern: decreasing after the stressor and returning to baseline after the second rest period. The results show that even a short lasting mild psychological stressor can affect parameters of the immune system.