title: Usefulness of complement activation products in Chinese patients with systemic lupus erythematosus.
abstract: OBJECTIVE
  To evaluate the roles of complement activation products C3d and C4d binding to lymphocytes in the diagnosis of systemic lupus erythematosus (SLE) in a Chinese cohort of patients.
  
  
  METHODS
  96 patients with SLE, 44 patients with other autoimmune disease and 40 healthy control individuals were enrolled in this study. The levels of C3d and C4d binding to peripheral CD4+ T and CD19+ B lymphocyts (designated as T-C3d, T-C4d, B-C3d, B-C4d ) was assessed by flow cytometry. The diagnostic values of these biomarkers were determined by receiver-operator characteristic analysis.
  
  
  RESULTS
  The levels of T-C3d, T-C4d, B-C3d, B-C4d were significantly higher in SLE patients than patients with other disease and healthy controls (p<0.01). As diagnostic tools, T-C4d and B-C4d were 61.1% sensitive/94.3% specific and 63.9% sensitive/94.3% specific in differentiating SLE patients from patients with other disease and healthy controls, respectively. T-C4d and B-C4d were significantly associated with SLE disease activity as measured by the SLE disease activity index (SLEDAI) (p<0.001), low serum C3 (p<0.001), low serum C4 (p=0.006), anti-dsDNA (IIF) (p=0.001), and anti-dsDNA (ELISA) (p=0.001).
  
  
  CONCLUSIONS
  Complement activation products C3d and C4d binding to lymphocytes can reflect the disease activity of SLE and can be used as biomarkers for SLE.
authors: Rheumatology and Clinical Immunology Department, Peking University First Hospital, Beijing, China; Renal Department, General Hospital of Tisco, Shanxi, China. xiaodaizi.521@163.com.
authors: Juan
authors: J
authors: Li
authors: Lemei
authors: L
authors: An
authors: Zhuoli
authors: Z
authors: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018941:Antigens, CD19 / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002681:China; D003167:Complement Activation; D015933:Complement C3d / Q000378:metabolism; D015935:Complement C4b / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016015:Logistic Models; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010446:Peptide Fragments / Q000378:metabolism; D011237:Predictive Value of Tests; D011379:Prognosis
chemical_list: D018941:Antigens, CD19; D015415:Biomarkers; D010446:Peptide Fragments; D015933:Complement C3d; D015935:Complement C4b; C032261:complement C4d