The association between low-grade inflammation and the clinical features of bipolar disorder in Han Chinese population.

•Prevalence of low-grade inflammation among bipolar disorder in Han Chinese population is about 10 %.•Low-grade inflammation of different definition impacts differentially on the clinical features of bipolar disorder.•Low-grade inflammation (C-reactive protein levels>3 mg/L) is associated with recent suicide attempt and family history of mental disorders.•Low-grade inflammation (white cell count > 9.5 × 109/L) is related with psychotic features and previous adverse life events.