BACKGROUND:

The role of the immune system in mood disorders is predominately supported by studies in unipolar major depression. However activation of the immune system has also been demonstrated in bipolar mania. Our study examines pro-inflammatory and anti-inflammatory cytokines in both phases of bipolar affective disorder (BPAD).

METHODS:

Plasma concentrations of IL-6, IL-8, IL-10, TNF-alpha and sIL-6R were measured with enzyme linked immunosorbent assays (ELISA) in patients with BPAD who were depressed, or manic and in healthy controls.

RESULTS:

Bipolar depression had significantly higher production of the pro-inflammatory cytokines, IL-8 (p < 0.001) and TNF-alpha (p < 0.05) compared to healthy subjects. The manic group also had increased production of IL-8 (p < 0.05) and TNF-alpha (p < 0.001) as compared to healthy subjects. Anti-inflammatory cytokine levels did not differ across the 3 groups.

LIMITATIONS:

A small sample size was studied. All patients remained on medication for this study.

CONCLUSIONS:

BPAD is associated with increased production of pro-inflammatory cytokines both in the manic and in the depressed phase as compared to healthy subjects. This is the first study, which examined both mania and bipolar depression.