Serum IgE level is negatively correlated with the ability of peripheral mononuclear cells to produce interferon gamma (IFNγ):: evidence of reduced expression of IFNγ mRNA in atopic patients

Background In patients with atopic diseases such as bronchial asthma and atopic dermatitis, an elevated serum IgE level is common. Several studies showed that interleukin-4(IL-4) and interferon-gamma (IFN gamma) are important for regulation of IgE production. Objectives The study was designed to examine the pathogenesis of an elevated serum IgE level at the production levels of TH1-type and TH2-type cytokines. Methods The production of interleukin-2 (IL-2), IL-4, interleukin-5 (IL-5) and IFN gamma by peripheral blood mononuclear cells (PBMCs) stimulated with phytohemagglutinin (PHA) was analysed in 20 individuals with various serum IgE levels. The amount of IFN gamma mRNA in the stimulated PBMCs was analysed using a quantitative polymerase chain reaction method. Results Cytokine production was analysed simply as a function of serum IgE level. The serum IgE level was negatively correlated with the amount of IFN gamma secreted by PBMCs (n = 20, R = -0.724, P < 0.005) when logarithmically transformed data were analysed, but were not or were only weakly correlated with those of IL-4, IL-2, or IL-5 secreted by these cells (n = 20). For investigation of the cause of reduced IFN gamma production in individuals whose serum IgE level are high, the amount of IFN gamma mRNA was determined. The levels of IFN gamma mRNA expression in the stimulated PBMCs correlated well with the amount of IFN gamma secreted by the PBMCs (n = 8, R = 0.947, P < 0.001). Conclusions Reduced IFN gamma production ability due to reduced IFN gamma mRNA expression in PBMCs is associated with an elevated serum IgE level in atopic patients.