Immunoglobulin E and immunoglobulin G subclass distribution in vivo and relationship to in vitro generation of interferon-gamma and neopterin in patients with severe atopic dermatitis.

In vitro interferon-gamma (IFN gamma) and neopterin generation by peripheral blood mononuclear cells (PBMC) from 15 patients with severe atopic dermatitis (AD) and 10 healthy controls was investigated. A significant proportion of patients had an impaired capacity to secrete IFN gamma after phytohemagglutinin (PHA) stimulation in vitro and therefore IFN gamma production was significantly lower compared to controls. Neopterin generation in vitro did not differ significantly from that of controls and no correlation between in vitro IFN gamma and neopterin production could be observed in either group. Analysis of serum IgG subclass distribution showed that patients with AD. had increased IgG4 serum concentrations while IgG1, IgG2 and IgG3 levels did not differ significantly from those of controls. Surface marker analysis revealed increased numbers of CD23+ lymphocytes in patients with AD which was positively correlated with the serum IgG4 and IgE concentration. Furthermore, a significant correlation was found between IFN gamma generation in vitro and IgE and IgG4 concentration in vivo in AD. The data suggest that a possible dysregulation of IFN gamma, interleukin-4 or other lymphokine interleukin-4 or other lymphokine production may be related to increased IgE and IgG4 production and seems to be an important factor in the pathogenesis of AD.