Explanatory style and cell-mediated immunity in elderly men and women.

Correlated pessimistic explanatory style--the belief that negative events are caused by internal, stable, and global factors--with lowered immunocompetence in a sample of 26 older adults. Two measures of cell-mediated immunity--T-helper cell/T-suppressor cell ratio and T-lymphocyte response to mitogen challenge--were lower in individuals with a pessimistic style, controlling for the influence of current health, depression, medication, recent weight change, sleep, and alcohol use. A relative increase in the percentage of T-suppressor cells seemed to underlie this immunosuppression. Although the mechanism by which explanatory style might influence immune function remains unknown, we speculate that a pessimistic style might be an important psychological risk factor--at least among older people--in the early course of certain immune-mediated diseases.