Immune correlates of stress and depression.

This paper reviews the evidence for alterations in immunity associated with depression and stressful events. The reviewed studies examine a variety of immune parameters (e.g., mitogen response, natural killer cell activity and number, T-cell, and T-cell subpopulations) in relation to depression and in relation to a number of stressful events (e.g., death of spouse, examinations). There is considerable variability in the findings of the available studies. However, the review finds considerable evidence for an association between a variety of stressful events and lowered immunity and between severe depression and lowered immunity. The clinical relevance of these psychoimmune relationships remains in question.