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 (IFNγ) are important for regulation of IgE production.
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.
The production of interleukin-2 (IL-2), IL-4, interleukin-5 (IL-5) and IFNγ by peripheral blood mononuclear cells (PBMCs) stimulated with phytohemagglutinin (PHA) was analysed in 20 individuals with various serum IgE levels. The amount of IFNγ mRNA in the stimulated PBMCs was analysed using a quantitative polymerase chain reaction method.
Cytokine production was analysed simply as a function of serum IgE level. The serum IgE level was negatively correlated with the amount of IFNγ 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 IFNγ production in individuals whose serum IgE level are high, the amount of IFNγ mRNA was determined. The levels of IFNγ mRNA expression in the stimulated PBMCs correlated well with the amount of IFNγ secreted by the PBMCs (n = 8, R = 0.947, P < 0.001).
Reduced IFNγ production ability due to reduced IFNγ mRNA expression in PBMCs is associated with an elevated serum IgE level in atopic patients.