We investigated the role of human interleukin-6 (IL-6) in the regulation of the third component of complement (C3) biosynthesis by cultured rat liver epithelial cells. A natural human IL-6 (nh IL-6) preparation was shown to up-regulate C3 production, whereas an Escherichia coli-derived recombinant human IL-6 (rh IL-6) displayed no activity on C3 biosynthesis. However, the C3-stimulating activity of the nh IL-6 preparation was only partially reduced when treated with an antihuman IL-6 monoclonal antibody. Binding studies indicated that although it was devoid of any C3 stimulating activity, rh IL-6 specifically bound to hepatic cell receptors (Kd = 0.38 nM) and possessed the same binding affinity as nh IL-6. Furthermore, the substitution of natural IL-6 molecules for the recombinant IL-6 led to the recovery of the initial C3-stimulating activity. These studies demonstrated that human IL-6 alone does not stimulate rat liver epithelial cell C3 production but is able to accentuate the C3-stimulating activity of unrecognized components which are present in the nh IL-6 preparation. Human IL-6 thus appears to act as a co-factor for the up-regulation of hepatic C3 production.

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PubMedDate not supplied

Tophaceous gout of the foot: an unusual presentation of severe chronic gout in an undiagnosed patient.

Tophaceous deposits are frequently noted within articular cartilage, synovium, tendons, tendon sheaths, pinnae and the soft tissue on the extensor surface of the forearms, feet, and bursae in patients with a history of chronic gout. The authors describe an unusual case of severe chronic tophaceous gout without prior diagnostic history or presence of acute attacks. They describe the procedure for the excision of these masses as well as the radiographic and pathological findings.

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PubMedDate not supplied

[Menkès disease. Study of copper-dependent enzymes].

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Biogenic Amines↗