IgE deposition in normal skin of patients with rheumatoid arthritis in relation to clinical and laboratory findings.

Biopsy specimens from apparently normal skin of 28 patients with classical or definite rheumatoid arthritis (RA) were examined for the presence of IgE deposition by a direct immunofluorescence technique. IgE deposition was found in 12 patients (43%) and in none of the 10 controls. This deposition was mainly localised on mast cells, and in three patients perivascular IgE staining was also noted. The skin from nine of the 12 patients also showed deposition of IgM and complement C3 or C4 factor, or both. All 12 patients with skin IgE deposition had raised levels of IgM rheumatoid factor (RF) in the serum. Nine of these also had IgE RF. IgE-containing circulating immune complexes (IgE CIC), raised serum IgE levels, and extra-articular (EA) manifestations were present in respectively 10, nine, and eight skin IgE positive patients. It is suggested that IgE and IgE CIC may be involved in the pathogenesis of RA and its EA manifestations.