Observations on the Presence of Rheumatoid Serum Factor in Skin and Other Tissues.

It has been known for some time that there is an association between rheumatoid serum factor and rheumatoid subcutaneous nodules (Ball, 1950). This suggests that serum factor may be produced in areas of tissue damage, or perhaps be concentrated there. In either case, serum factor might be extractable in greater amounts from the nodules than from either the healthy tissues of the same subject or the non-rheumatoid tissues. This line of reasoning, which initiated the experiments described below, takes no account of immunofluorescent microscopic studies of the localization of rheumatoid factor because most of the experiments were carried out before those studies had been reported. Immunofluorescent microscopy shows that, in the subcutaneous nodules, synovial membranes, and lymph nodes of rheumatoid subjects, serum factor occurs almost exclusively in plasma cells; and it has been suggested that serum factor is synthesized by these cells (Mellors, Heimer, Corcos, and Korngold, 1959; Mellors, Nowoslawski, and Korngold, 1961). The experiments reported here, concerned as they are with the extraction of serum factor from various tissues, constitute a different approach to this problem of the source of rheumatoid serum factor; the findings indicate that skin contains significant amounts of serum factor and might be an additional site of synthesis of this protein.