Background: A shift in the balance ofT helper (Th) cell subsets towards a polarized Th2 population is generally accepted to occur in atopic disease, however, both Th1 and Th2 disorders have increased over the past decades in Western communities.
Objective: The aim of our study was to investigate delayed type hypersensitivity (DTH) response in atopic and non-atopic children in a population with a low prevalence of allergic disorders.
Methods: Skin prick tests (SPT) were performed with fresh egg white and extracts of five inhalant allergens, i.e. cat, dog, house dust mite (Dermatophagoides pteronyssinus), birch and timothy, and DTH response was evaluated by Multitest CMI in 72 Estonian 4- to 6-year-old children.
Results: The frequency of response to diphtheria was significantly increased in SPT-positive children (55% vs. 26%, chi2 = 5.5; P = 0.038). The induration to diphtheria (2.4 +/- 0.5 vs. 0.9 +/- 0.2 mm; P = 0.004), and tetanus (3.5 +/- 0.6 vs. 2.1 +/- 0.3 mm; P = 0.025) was significantly greater in the SPT-positive children. The cumulative size of induration in the positive DTH tests was significantly greater in the SPT-positive children (9.0 +/- 1.2 vs. 5.2 +/- 0.6 mm, P = 0.01).
Conclusion: In this group of children our findings do not support the hypothesis of an immune deviation with decreased Th1 and increased Th2 responses leading to atopic disease, but rather a process of immune modulation whereby both Th1 and Th2 responses are increased in atopic subjects.