Psychological stress and phorbol ester inhibition of radiation-induced apoptosis in human peripheral blood leukocytes

Apoptosis is a process of genetically programmed alternations of cell structure that lead to failure of proliferation and differentiation, and eventual cell death. Apoptosis is induced by a variety of toxic insults including growth factor deprivation and ionizing radiation. This process may function to protect against the appearance of heritable phenotypic changes in cells and may be a critical factor in normal cellular immune function. Phorbol esters inhibit apoptosis, but little is known about factors that regulate this process physiologically. In this study, we demonstrate an association between an acute psychological stressor, taking examinations, and the induction of substantial and reversible changes in the response of peripheral blood leukocytes to gamma irradiation and to phorbol ester treatment. These data suggest that psychological stress may induce physiological changes that regulate the ability of immune cells to initiate apoptosis.