Rheumatoid arthritis with monoclonal IgE rheumatoid factor.

We studied a patient with rheumatoid arthritis (RA) and a high titer of IgE that could be attributed to a mono or oligoclonal expansion of IgE+ B lymphocytes. These IgE had no specificity for known allergens but bound to a panel of self (including Fc fragment of IgG) and exogenous antigens, displaying properties typical of polyspecific antibodies. We concluded that (1) RA can be associated with increased amounts of polyspecific IgE antibodies; (2) clonal excess populations of B cells are not a unique feature of malignant lymphoma, but may occur in autoimmune diseases in the form of a benign oligoclonal B cell proliferation.