Background: Several studies have shown that interleukin (IL)-4 and interferon-gamma (IFNgamma) are important for the regulation of IgE production and that IL-12 induces IFNgamma.
Objective: IFNgamma production in response to IL-12 stimulation and IL-12 production were investigated in peripheral blood mononuclear cells (PBMCs) of atopic patients with various levels of serum IgE.
Methods: Cytokine production from PBMCs was measured following stimulation with a nonspecific stimulator (phytohemagglutinin: PHA), a specific stimulator (Der f 1) and IL-12 in 17 healthy controls and 23 atopic patients with various serum IgE levels.
Results: The IFNgamma production by IL-12-stimulated PBMCs in the atopic group was lower than that in the control group. Furthermore, the serum IgE level was negatively correlated with IFNgamma production by PBMCs stimulated with IL-12 (P < 0.001), and with IL-12 production by PBMCs stimulated with Der f 1 (P < 0.001). Although the IFNgamma concentrations by PHA-stimulated PBMCs were correlated with those by IL-12-stimulated PBMCs, there were differences in several patients.
Conclusions: Our results indicated that atopic patients may have some abnormality in the IL-12-IFNgamma loop. It was shown that the elevation in IgE levels in atopic patients may be due to reduced IFNgamma production in response to IL-12 stimulation and/or due to reduced IL-12 production.