Lymphocyte stimulation by phytohemagglutinin, concanavalin A, and pokeweed mitogen was significantly lower in a group of hospitalized depressed patients than in matched controls. The absolute number of T and B cells was lower in the depressed group, but the percentage of these cell types did not differ between the groups. These findings may be related to the altered neuroendocrine function found in patients with depressive disorders.
Schleifer SJ, Keller SE, Meyerson AT, Raskin MJ, Davis KL, Stein M. Lymphocyte Function in Major Depressive Disorder. Arch Gen Psychiatry. 1984;41(5):484-486. doi:10.1001/archpsyc.1984.01790160070008