T-cell cytokine pattern at three time points during specific immunotherapy for mite-sensitive asthma

Backgrounds: Several lines of evidence indicate that specific immunotherapy may act by modifying the patterns of cytokines produced by helper T cells. However, different protocols have been used and different results obtained. Objectives: To quantify the effect of specific immunotherapy on the TH1/TH2 T-cell cytokine pattern at the single cell level. Methods: We examined the interferon-γ/interleukin-4 ratio in peripheral blood CD4 ⁺ and CD8 ⁺T cells from 12 subjects with house dust mite-sensitive asthma using a flow cytometric method of intracellular cytokine detection. Cytokine production was determined following stimulation with phorbol myristate acetate/ionomycin, a policlonal activator. Subjects were examined at three occasions: before specific immunotherapy, after the 3- months dose increase phase and after 1 year of treatment. During the treatment year patients kept a diary in which they recorded: (a) symptoms of asthma according to a 0-3 grading (0 = absent, 1 = mild, 2 = moderate, 3 = severe); (b) number of puffs (100 μg) per day of salbutamol required to control symptoms; and (c) peak expiratory flow. Results: Specific immunotherapy improved clinical indices of disease activity including symptom scores and medication use during the treatment year, and had a marked effect in increasing the interferon-γ/interleukin-4 ratio in peripheral blood CD4 ⁺ T cells already after the dose increase phase (5.47 ± 1.5 vs 4.07 ± 1.49%, P = 0.03) with and a further rise after 1 year's treatment (16.12 ± 2.8 vs 4.07 ± 1.49 and 16.12 ± 2.8 vs 5.47 ± 1.5%, P = 0.001 and P = 0.002, respectively). There were no significant changes in the interferon- γ/interleukin-4 ratio in peripheral blood CD8 ⁺T cells at the three times of the study. Conclusions: These data add to view that the efficacy of specific immunotherapy may be attributed to a modified cytokine secretion of CD4 ⁺ T cells.