RESUMO
OBJECTIVES/HYPOTHESIS: Markedly elevated immunoglobulin E (IgE) synthesis characterizes allergic diseases. Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) regulate IgE synthesis. It has been shown that immunotherapy and histamine type 2 (H2) receptor antagonists induce a clinical improvement, decrease IgE antibodies, and increase T-cell subsets, which express a suppressor function. In addition, immunotherapy brings about a reduction in the amount of IL-4 in T-cell clones of allergic individuals. The purpose of this study was to investigate the profile of cytokines IFNgamma and IL-4 that occurs in vivo in anti-H2-treated patients with allergic rhinitis (AR). METHODS: Enrolled were 65 AR patients with sensitivity to a single allergen, the Parietaria, 36 of whom were randomly assigned to treatment with ranitidine at a dosage of 1 mg/kg per day intravenously for 20 days, and 29 to placebo treatment. RESULTS: A comparison of the serum cytokine values recorded before and after anti-H2 treatment showed a significant increase in INF-gamma serum level (P = .003) and a decrease in IL-4 (P = .016). Negligible variations were found in the placebo-treated group. CONCLUSION: H2 antagonists probably induce their effects by enhancing the amount of IFN-gamma and by reducing IL-4 cytokines, which, respectively, induce a decrease and an increase in the IgE synthesis.
