Anti-interleukin-6 and soluble interleukin-6 receptor in systemic lupus erythematosus.
IL-6, soluble IL-6 receptor and IgG with anti-IL-6 activity were measured in the plasma of 14 lupus patients and 10 normal subjects. The capacity of peripheral blood mononuclear cells to spontaneously produce IL-6 in vitro was also measured. Our results indicate that IL-6 plasma levels in patient plasma as measured by ELISA were not different from normal but that supernatant levels were significantly lower than normal (P < 0.05). In vitro IgG production was comparable for all lupus patients' cells irrespective of the in vitro IL-6 levels. Plasma soluble IL-6 receptor levels directly correlated with IL-6 production capacity of SLE cells and the ratio of soluble receptor to anti-IL-6 directly correlated with IL-6 production in patients but not in normals. Inhibition assays demonstrated competition between anti-IL-6 and soluble receptors for IL-6 and the inhibition by plasma of IL-6 binding to monoclonal anti-IL-6. We believe the interaction of anti-IL-6 and IL-6 receptor with IL-6 may contribute to the homeostasis in IL-6 activity in vivo and skewing of the soluble receptor/anti-IL-6 ration may contribute to the lupus disease process.
Immunology Research Laboratory, St. Luke's Hospital, Kansas City, MO 64111.
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M
Evans
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Abdou
D002478:Cells, Cultured; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood / Q000276:immunology*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D018123:Receptors, Interleukin / Q000032:analysis*; D019947:Receptors, Interleukin-6
D007074:Immunoglobulin G; D015850:Interleukin-6; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6