Age, cellular immunity and the HP axis in major depression

1. To assess the effect of age on cellular immune status and the HP axis in patients with major depression, we examined peripheral blood mononuclear cells (PBMC) and measured the plasma level of four neurohormones. 2. In 36 subjects, decreasing T lymphocyte response to con A covaried with age. Percent of lymphocytes labeled as T8 lymphocytes tended to decrease and T4/T8 ratio tended to increase with increasing age. 3. Hamilton and Beck scores were significantly different between the two sex and race matched groups of 18 depressed patients and 18 control subjects, and plasma prolactin was significantly higher in depressed subjects. 4. Increasing age correlated with decreasing T lymphocyte response to con A in the combined group of all subjects, and in the control group, but not in the patient group. 5. Hamilton and Beck scores correlated inversely with T lymphocytes response in the combined group of all subjects. 6. Differences in mitogen responsiveness between patient and control groups were not found, having been obscured by the effect of age. 7. These findings indicate the need to age match subjects when studying the interaction between depression and immune cell function.