T cell subsets and cytokines in allergic and non-allergic children. I. Analysis of IL-4, IFN-gamma and IL-13 mRNA expression and protein production.

Interleukin 4 (IL-4) and IL-13 are key cytokines inducing switching to immunoglobulin E (IgE), whereas interferon gamma (IFN-gamma) acts inhibitory on this process. We analysed whether differences existed in IL-4, IFN-gamma and IL-13 mRNA expression and protein production between T cells of children with allergic and non-allergic asthma, atopic dermatitis and health control children. IL-4 mRNA expression was increased in stimulated T cells of children with allergic asthma and atopic dermatitis, but not in those with non-allergic asthma as compared with healthy controls. Thus the increase in IL-4 expression can be considered as an underlying mechanism of the allergic disease process and not so much of the asthmatic state of the children. In unstimulated T cells of children with atopic dermatitis increased IFN-gamma mRNA expression with a reduced IFN-gamma protein production was found, indicating a post-translational defect in IFN-gamma. Differences in IL-13 expression between the groups were not significant, but IL-13 was significantly correlated with the height of the radio-allergo-sorbent test (RAST) class and with the severity scoring of atopic dermatitis (SCORAD) index. This indicates the clinical relevance of IL-13 for the degree of allergen-specific sensitization and severity of atopic dermatitis. In conclusion, the imbalance in IL-4 and IFN-gamma secretion in patients with atopic dermatitis may reflect general T cell activation in the presence of an intrinsic defect of IFN-gamma secretion.