IL6 and systemic lupus erythematosus: We investigated a possible association between serum concentrations of tumour necrosis factor α (TNF-α), interleukin-6 (IL-6) and their soluble receptors (sTNF-α-Rp55 and sIL-6R) using an enzyme-linked immunosorbent assay (ELISA) in 55 patients with systemic lupus erythematodes (SLE) and 16 healthy controls.