Increased mitogen-induced lymphocyte proliferation in treatment resistant depression: a preliminary study.

The biological basis of treatment resistance in depression still remains unclear. Some studies suggest that there exists a relationship between a disturbance in the immune system and depression.To investigate the immune status of patients with treatment resistant depression, we compared the in-vitro lymphocytic responses to three different mitogens in 10 drug-free patients with treatment resistant depression and 10 normal controls matched for age and sex.We observed a marked increase in the lymphocyte mitogenic activity to mitogens of T lymphocytes.This activation of lymphocyte function may be indicative of a pathological stimulation in cell-mediated immunity in patients with treatment resistant depression.