Responsiveness to interleukin 4 and interleukin 2 of peripheral blood mononuclear cells in atopic dermatitis

Although the pathogenesis of atopic dermatitis (AD) is unknown, many immunologic abnormalities such as high levels of serum IgE and increase of IgE Fc receptor-positive lymphocytes have been demonstrated. Recently, interleukin 4 (IL-4) has been shown to induce enormously the production of IgE and to enhance the expression of IgE Fc receptor by B cells, suggesting the possible involvement of IL-4 in the pathogenesis of AD. We examined IL-4 responsiveness or interleukin 2 (IL-2) responsiveness of peripheral blood mononuclear cells of 31 patients with AD, 19 healthy individuals, and seven patients with other skin diseases. We found that IL-4 responsiveness of AD was higher than that of non-AD control, although IL-2 responsiveness of AD showed no significant change. However, the value of the IL-4 responsiveness did not significantly correlate with the clinical severity, personal history of respiratory allergy, serum IgE level, or clinical course of patients with AD. The hyperresponsiveness to IL-4 detected in AD was not likely to be due to the effects of steroids or anti-mast cell drugs because the value of IL-4 responsiveness was significantly low, compared to AD, in patients with other skin diseases who were treated similarly. Because the T-cell-enriched population, but not the B-cell-enriched population, showed significant proliferation in response to exogenous IL-4 or IL-2, T cells were the main population that reacted in our proliferation assay. These results indicate that IL-4-driven proliferative response may be efficiently operative in T cells in patients with AD.