Cross-sectional study on cytokine polymorphisms, cytokine production after T-cell stimulation and clinical parameters in a random sample of a German population

We investigated, in a random sample of a German population, the association of polymorphisms in the genes encoding the cytokines interleukin 2 (IL-2), interleukin 4 receptor (IL-4R), interleukin 6 (IL-6), interleukin 10, interferon gamma (IFNG), tumor necrosis factor (TNF) and intercellular adhesion molecule 1 (ICAM-1) with (1) secreted levels of the respective proteins after T-cell stimulation and (2) data on selected diseases obtained from a questionnaire. The scope of this investigation was to further the understanding of the genetic background of allergies and common colds and the observed heterogeneity of many immune responses in the human population. In contrast to previous reports that showed associations of promoter polymorphisms of cytokine genes with the production of the corresponding protein, we did not find associations with protein release after T-cell stimulation in vitro. Among the correlations with the clinical parameters, we observed an increased risk of allergies (odds ratio, OR = 4.1; confidence interval, CI: 1.6-10.4), particularly hay fever (OR=5.6, CI: 1.8-17.1) in individuals homozygous for IFNG 13 CA-repeats. In combination with the TNF wildtype, the risk for hay fever increased to OR=8.4 (CI: 2.7-25.6). Furthermore, individuals with a combination of IL2, IL6 and ICAM-1 polymorphisms tended to have higher frequencies of reported common colds than individuals with the alternate genotypes. As these are results of an explorative investigation, these findings require confirmation in material from a different source. If confirmed, these relationships could contribute to a better characterisation of the genetic component of allergies.