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Rituximab Improves Atopic Dermatitis

Rituximab is a synthesized monoclonal antibody to CD20, a nonglycosylated phosphoprotein expressed on the surface of pre–B cells and mature B cells but not on plasma cells. These authors treated six adult patients with atopic dermatitis (mean Eczema Area and Severity Index [EASI] score before treatment, 29) with 1000 mg of rituximab administered by intravenous infusion and repeated 2 weeks later.

Symptoms in all six patients improved within 4 weeks and continued to improve; by 8 weeks, the mean EASI score was 8 (P<0.001). Peripheral blood B-cell levels were "undetectable," and skin-infiltrating B-cell levels decreased by 50%. Total IgE levels were only slightly reduced, and allergy-specific IgE levels remained unchanged. The authors assessed changes in cytokines by assessing changes in mRNA and cytokine expression as illuminated by immunofluorescence. Interleukin (IL)-5 decreased by a mean of 53% and IL-13 by a mean of 83%, while levels of interferon- and IL-10 remained virtually unchanged, with reduced numbers of infiltrating T cells in the skin lesions. Although B cells reappeared in blood in three of the six patients by 24 weeks, all six patients maintained low EASI scores.

Comment: So, how does it work? B cells and antibodies do not cause eczema. B cells differentiate to plasma cells, and plasma cells secrete IgE and other immunoglobulins. Although high serum IgE levels are associated with atopic dermatitis in 80% of patients, and although all six study patients had elevated IgE serum levels, these serum levels were basically unchanged by treatment. The authors suggest a role for B cells in antigen presentation in atopic dermatitis and in chemoattraction of other immune cells. Perhaps. If these results are confirmed, and severe atopic dermatitis reliably and safely responds to rituximab, we may have a valuable therapy for selected patients. Moreover, if rituximab does work well, studying how it works will give us valuable new clues about the cause and pathobiology of atopic dermatitis.

— Mark V. Dahl, MD

Published in Journal Watch Dermatology February 22, 2008

Citation(s):

Simon D et al. Anti-CD20 (rituximab) treatment improves atopic eczema. J Allergy Clin Immunol 2008 Jan; 121:122.