title: Serum and urinary interleukin-6 in systemic lupus erythematosus.
abstract: Dysregulation of IL-6 production has been proposed as a pathogenic mechanism in SLE. We asked if serum or urine IL-6 levels could serve as indicators of systemic lupus erythematosus (SLE) disease activity. Using a sensitive enzyme-linked immunosorbent assay (ELISA), we measured serum and urine IL-6 in 56 SLE patients. Disease activity was assessed using a standard clinical index, the Systemic Lupus Activity Measure (SLAM). Only seven of 56 SLE patients had elevated serum IL-6 levels, compared with 1 of 32 controls (NS). SLE disease activity did not correlate with serum IL-6 levels. Sixteen of 50 SLE patients in whom urine IL-6 was measured exhibited elevated urine IL-6 levels, compared with 1 of 17 controls (p = < 0.05). Urine IL-6 levels correlated with overall disease activity and with the presence of active urinary sediment. Our results indicate that serum IL-6 is not a predictor of disease activity in SLE, but that urine IL-6 may be a marker of active nephritis.
authors.affiliation: Division of Rheumatology, University of Iowa College of Medicine, Iowa City, USA.
authors.forename: E
authors.initials: E
authors.lastname: Peterson
authors.forename: A D
authors.initials: AD
authors.lastname: Robertson
authors.forename: W
authors.initials: W
authors.lastname: Emlen
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood* / Q000652:urine; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000652:urine; D008297:Male; D008875:Middle Aged
chemical_list: D015415:Biomarkers; D015850:Interleukin-6