There is now some evidence that depressed mood is associated with activation of the immune system. First, we evaluated, within a cross-sectional design, NKCA (in vitro) in 49 subjects meeting inclusion criteria either for a major depressive episode, for dysthymia, or for "double depression". We found that recent and long depressive episodes (dysthymia) are associated with a lower immunodepression. Second, we compared two subset of subjects: 14 patients meeting criteria of major depression to 14 healthy controls. The data show a significant improvement in major depression when compared to controls througout a treatment combining supportive psychotherapy and 8 mg Reboxetine™.
Reynaert, C., Janne, P., Jacques, D., Tordeurs, D., & Zdanowicz, N. (2010). Natural killer cell cytotoxity and course of illness in depressed mood. Psychiatria Danubina, 22 Suppl 1, S132-4. https://hdl.handle.net/2078.5/157912 (Original work published 2010)