Immune dysfunction in affective subtypes

Affective disorders have been associated with alterations in immune function. We previously noted differences in acute phase and immuno-modulatory proteins in bipolar I (BPI) as compared to unipolar depressives (MDD). In this study, C-reactive protein (CRP, a positive acute phase protein or APP), transferrin (TFN, a negative APP), antithyroid (antimicrosomal and antithyroglobulin), antinuclear (ANA), anti-dsDNA, and anticardiolipin antibodies (IgM and IgG) were measured in sera from 88 BPI, 19 BPII, 42 MDD patients and 23 healthy controls. The frequency of positive CRP responses was significantly higher in both BPI and MDD patients vs. controls (10 and 19%, respectively, vs. 4% of controls; X2 = 15.372, p = 0.009), but not in BPII individuals (0% CRP positive). No differences among diagnostic subgroups were observed for other autoimmune or acute phase variables. Females were much more likely than males to demonstrate elevated cardiolipin IgM (Mann-Whitney U = 2896.5, p = 0.0035) and ANA antibodies (Mann-Whitney U = 2437.5, p < 0.0001). Elevations in positive acute phase immune proteins may help to distinguish certain affective subtypes (e.g., BPI and MDD populations) from controls. Given the higher incidence of both depressive and autoimmune disease in female populations, our current finding that females had higher levels of certain autoantibodies also implies that gender must be strictly controlled in studies of autoimmunity in affective disorders.