C3 and systemic lupus erythematosus: To determine the functional implication of lower TGFβRI expression in SLE patients, we assessed the correlations of the TGFβRI mRNA level with disease-related variables, including SLEDAI score, disease duration, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), complement C3 and C4, 24-h urine protein, and serum creatinine (Scr).