Effect of house dust mite immunotherapy on transforming growth factor beta1-producing T cells in asthmatic children.

BACKGROUND

Recent evidence suggests that regulatory T cells (Treg cells) and immunosuppressive cytokines, such as transforming growth factor BETA1 (TGF-BETA1) and interleukin 10 (IL-10), may have a role in clinically effective allergen specific immunotherapy (SIT).

OBJECTIVE

To evaluate the effect of SIT on the induction of Treg cells in house dust mite-allergic children and on the expression of specific Treg cell markers (cytotoxic T-lymphocyte-associated protein 4 [CTLA-4], IL-10, and TGF-BETA1).

METHODS

In this uncontrolled open-label study, the percentage of peripheral blood CD4+ Treg cells (CD69 CD45RO+CTLA-4+ and CD3+CD4+CD25+FOXP3+) and the expression of molecules associated with their functions (CTLA-4, TGF-BETA1, and IL-10) were analyzed using flow cytometry in 16 children allergic to house dust mites before and at 3 and 12 months of subcutaneous SIT. Clinical variables, such as symptom score, medication requirements, forced expiratory volume in 1 second, peak expiratory flow rate, and serum IgE levels, were also determined. Ten healthy children were included as controls.

RESULTS

All the clinical variables improved during immunotherapy. The percentage of CD4+CD25+CD69-CD45RO+ Treg cells remained unchanged. The percentage of CTLA-4+ -expressing Treg cells transiently increased after 3 months of immunotherapy, whereas the percentage of FOXP3+ Treg cells did not change after 1 year of immunotherapy. Levels of IL-10+ cells transiently decreased after 3 months of immunotherapy. Four children who required inhaled fluticasone propionate administration for significant symptom worsening had no statistically significant increase in TGF-BETA1-secreting T cells at 12 months of SIT, in contrast to 12 children without inhaled corticosteroid treatment.

CONCLUSIONS

The increase in TGF-BETA1-positive T cells only in children without significant symptom worsening requiring inhaled corticosteroid treatment limits the usefulness of TGF-BETA1 in monitoring response to allergen immunotherapy.