[Specific immunotherapy effect on peripheral blood T1/T2 lymphocytes in atopic patients]

Allergen-specific immunotherapy has been used for successful treatment of atopic diseases. They may act by modifying the patterns of cytokines produced by T cells. However, the precise mechanism by which it accomplishes these effects is still incompletely understood.

To evaluate the effect of one year immunotherapy on cytokines profiles T1 and T2 of peripheral blood lymphocytes in atopic patients.

We studied 10 atopic patients sensitised to common environmental allergens receiving immunotherapy over one year mean period. Six of these patients were studied before and after immunotherapy. Fourteen atopic patients untreated and 7 non-atopic subjects were used as control groups. Intracellular cytokine production (IFN-g; IL-4; IL-5; IL-10) was determined by flow cytometry following stimulation with phorbol myristate acetate (PMA), ionomycin and brefeldin. Mann-Whitney U and Wilcoxon non-parametric tests were utilized for the statistical analysis.

The expression of IL-4 and IL-5 in T cells, characteristically increased in atopic patients, respectively 13.8 (3.1 - 31.8) and 6.7% (1.0 -20.4), was significantly lower in the immunotherapy group [5.4 (2.9 -15.6) p=0.007 and 2.1% (0,6 - 4.8) p=0.035] and similar in the non-atopic control group. The levels of IFN-g did not differ between the studied groups but the ratio IFN-g / IL-4 produced by CD4+ T lymphocytes increased significantly in the patients receiving immunotherapy. In addition, there was an increase in the expression of IL-10 by T cells of the immunotherapy group compared to the non-atopic controls [1.9 (1.0 - 4.9) versus 1.4% (0.9 - 1.4) p=0.02], being more evident in CD8+ T lymphocytes. IL-10 correlated significantly with all the profile T2 cytokines (IL-4 and IL-5) and with the phenotype Tc2.

After one year of immunotherapy the peripheral T cells response to a polyclonal stimulation revealed a reduction in IL-4 and IL-5 production, characteristically increased in atopic disease. The increase of IL-10 that we found in our study suggested the existence of a profile T2 regulatory population, more evident in CD8+T lymphocytes.