Allergen immunotherapy in intermittent allergic rhinitis reduces the intracellular expression of IL-4 by CD8+ T cells

Background: T helper subset dysregulation is evident in allergic disorders. The role of T cytotoxic subsets is less understood. We investigated whether allergen immunotherapy in intermittent allergic rhinitis influences the intracellular expression of IL-4 and IFN-gamma by CD3(+)CD8(-) and CD3(+)CD8(+) cells. Methods: Nineteen adult patients with intermittent allergic rhinitis were evaluated before the pollen season, and then after one preseasonal course of subcutaneous allergen immunotherapy. Twelve healthy nonatopic patients matched for age and sex served as controls. Intracellular expression of IFN-gamma and IL-4 by CD3(+)CD8(-) (Th1 and Th2, respectively) and CD3(+)CD8(+) (Tc1 and Tc2, respectively) was estimated by flow cytometry in peripheral blood cells after stimulation with PMA and ionomycin. Results: Before immunotherapy the percentages of Th1, Th2, Tc1 and Tc2 did not significantly differ between the patients and the controls. After immunotherapy the percentage of Tc2 was lower in the rhinitic patients than in the controls (0.38% vs. 0.45%, p = 0.04). The percentage of Tc2 cells decreased significantly after immunotherapy in the intermittent allergic rhinitis group (0.64% vs. 0. 38%, p = 0.02) with tendency to decrease in ratios of Tc2/Tc1 (p = 0.059) and with no changes in ratios of Th2/Th1. The percentages of Th1, Th2 and Tc1 were comparable before and after immunotherapy within the rhinitic patient group. Conclusions: The preseasonal allergen subcutaneous immunotherapy applied to intermittent allergic rhinitis patients suppressed the percentage of IL-4 producing CD3(+)CD8(+) cells. Decreased number of CD3(+)CD8(+)IL-4(+) cells may participate in the regulatory mechanisms of immunotherapy. (c) 2007 Elsevier Ltd. All rights reserved.