CRP and major depressive disorder: Accumulating evidence implicates the immune system in the pathogenesis of major depression (MD).1 Low-grade inflammation, as indicated by higher (>0.3 mg/dL [>3 mg/L]) C-reactive protein (CRP) levels, is present in about one-quarter of patients with MD and longitudinally predicts occurrence of depressive symptoms.2,3 Results of studies4,5,6,7,8,9 have suggested specificity of the association of inflammation and depression to a subset of depressive symptoms.