Evidence suggesting involvement of interleukin-4 (IL-4) production in spontaneous in vitro IgE synthesis in patients with atopic dermatitis.

To investigate the regulatory role of interleukin-4 (IL-4) and interferon-gamma (INF-gamma) and their involvement in the abnormality of IgE synthesis in patients with atopic dermatitis (AD), we studied the effect of recombinant human IL-4 and INF-gamma, as well as blocking antibodies (Abs) to these lymphokines on spontaneous IgE synthesis by peripheral blood lymphocytes (PBLs) from patients with AD and from healthy control subjects. PBLs from patients with AD demonstrated elevated spontaneous IgE production that was not stimulated further by the addition of recombinant IL-4, whereas for the healthy control subjects, recombinant IL-4 increased spontaneous IgE production by PBLs. INF-gamma that has been previously demonstrated to antagonize the effect of IL-4 on IgE synthesis, decreased IgE production of patients with AD. Addition of Abs to INF-gamma did not change spontaneous IgE production for patients with AD or for healthy control subjects. Together with our observation that IL-4 Abs lowered the high spontaneous IgE production by PBLs from patients with AD, these results suggest that in AD, IL-4 production by lymphocytes, together with a lack of INF-gamma production, is at least partially responsible for the increased spontaneous IgE production.