Allergy in systemic lupus erythematosus. IgE levels and reaginic phenomenon.

Twenty-seven patients with systemic lupus erythematosus (SLE) were investigated for the presence of allergic reactivity, and serum IgE levels were measured by immunoassay. Compared to controls, SLE patients had significant increases of only allergic rhinitis and drug allergy. Despite the usual hyperimmunoglobulinemia in SLE, IgE levels were not elevated (mean: 251 IU). Because recent reports have noted elevated IgE in rheumatoid arthritis, this finding may suggest basic immunologic differences between rheumatoid arthritis and SLE.