Cytokine profile in systemic lupus erythematosus, rheumatoid arthritis, and other rheumatic diseases.

We investigated serum levels of interleukin-6 (IL-6), interferon-gamma (IFN-gamma), and tumor necrosis factor alpha (TNF alpha) from patients with systemic lupus erythematosus (SLE) and its various clinical manifestations of disease and from patients with rheumatoid arthritis (RA) and other rheumatic diseases. The serum levels of IL-6 and IFN-gamma were highly elevated from patients with SLE associated with lymphadenopathy (LN) or nephrotic syndrome (NS). On the contrary, the serum levels of TNF alpha were elevated from most patients with SLE associated with thrombocytopenia (TP). However, serum levels of TNF alpha were in the normal range from patients with SLE associated with NS, LN, or central nervous system disease. Of interest, patients with SLE associated with humoral immunodeficiency disorder, hypogammaglobulinemia, had highly elevated levels of serum IL-6. The concanavalin A-stimulated mononuclear cells (MNC) of patients with SLE associated with TP secreted highly elevated levels of TNF alpha compared to other patient groups. We suggest that abnormal production of various cytokines in SLE is an intrinsic defect of MNC and the immune system that may be the key element for a variety of clinical manifestations of this disease.