Hyperresponsibility to exogeneous interleukin 4 in atopic dermatitis.

Many humoral and cellular immunological abnormalities have been reported in atopic dermatitis (AD). Since interleukin 4 (IL-4) enhances IgE production and IgE-Fc receptor expression by B cells as well as [3H]-TdR incorporation by T cells, we hypothesized that IL-4 may play an important role in the regulation of the immune response in AD. We examined [3H]-TdR incorporation by peripheral blood lymphocytes from AD patients or from non-AD controls in the presence or absence of IL-4 or interleukin 2 (IL-2). We found that IL-4/IL-2 responsiveness was significantly higher in AD than controls, although the IgE levels did not seem to be correlated with IL-4/IL-2 responsiveness. It is possible that most humoral and cellular immunological abnormalities of AD may be due to this hyperresponsibility to IL-4.