Suppression of immunity by stress: effect of a graded series of stressors on lymphocyte stimulation in the rat.

In rats a graded series of stressors produced progressively greater suppression of lymphocyte function, as measured by the number of circulating lymphocytes and by phytohemagglutinin stimulation of lymphocytes in whole blood and isolated cultures. This evidence suggests that stress suppresses immunity in proportion to the intensity of the stressor.