Th2 Cytokine Levels Distort the Association of IL-10 and IFN- γ with Allergic Phenotypes

Abstract

The expression of allergic phenotypes involves complex inter-relationships among several Th2 and Th1 cytokines as well as the regulator cytokine interleukin (IL)-10. These direct or indirect interrelationships may distort the true associations of cytokine responses with these phenotypes. In this study, we aimed to clarify the effects of the regulatory cytokine IL-10 and Th1 cytokine interferon-gamma (IFN- γ ) on allergic phenotypes after adjusting for the correlations with Th2 cytokines. After adjusting for Th2 cytokines, IL-10 and IFN- γ were protective against atopy. Adjusted levels of IL-10 and IFN- γ stimulated with house-dust mite (HDM) were significantly lower in atopics than non-atopics, for IL-10 adjusting for IL-5 ( P = 0 .002 ), IL-13 ( P = 0 .012 ), IL-9 ( P = 0 .016 ), and IL-4 ( P = 0.043 ), and for IFN- γ adjusting for IL-5 ( P = 0 .005 ), IL-13 ( P = 0 .005 ), and IL-9 ( P = 0 .037 ). IL-10 and IFN- γ levels stimulated with phytohaemagglutinin (PHA) and staphylococcal enterotoxin B (SEB) exhibited a similar pattern. The adjusted levels of IL-10 and IFN- γ stimulated with HDM, PHA or SEB were all significantly negatively correlated with total serum IgE, except for IFN- γ stimulated with SEB. Levels of Th2 cytokines distort the associations of IL-10 and IFN- γ with allergic phenotypes. Removing the covariance with Th2 cytokines, both IL-10 and IFN- γ were protective against atopy.