Concentration and chemical state of copper in synovial fluid and blood serum of patients with rheumatoid arthritis.

It was recently reported (Niedermeier, Creitz, and Holley, 1962) that the copper concentration in synovial fluid from patients with rheumatoid arthritis was elevated by a factor of three. The observation that copper could not be dialysed out of either "normal" or rheumatoid synovial fluid led to speculation concerning the nature of the compounds with which this element was associated. It was shown (Schmid and MacNair, 1956) by immunoelectrophoresis that synovial fluid from patients with joint effusions contained ceruloplasmin. This paper presents for the first time quantitative determinations of ceruloplasmin in synovial fluid and shows that the increase in copper concentration in synovial fluid of patients with rheumatoid arthritis is due almost entirely to an increase in ceruloplasmin concentration.