Expression of IL-7 receptor in human peripheral regulatory T cells.

Background: Regulatory T cells (Tregs, CD4 + CD25(high) Foxp3(+)) play a crucial role in allergy and other inflammatory diseases. However, the isolation of viable Tregs on the basis of intracellular expression of specific Forkhead Box Protein P3 (Foxp3) is difficult. In this study we checked if the expression of IL-7 receptor (CD127) on the Tregs could be a useful marker for isolation of viable Treg Foxp3(+) cells.

Methods: Twenty-five patients sensitized to grass pollen with allergic rhinitis (AR) and ten healthy subjects were included. We compared Foxp3 expression in different CD4(+) T cell subsets by flow cytometry and we assessed the relationship between the expression of Foxp3 and CD127 within regulatory T cells.

Results: Within the CD(4)+ lymphocytes 3.68 ±2.0% showed expression of Foxp3, 51.82 ±8.03% of CD4(+)CD25(high) were Foxp3 positive (Foxp3(+)), whereas 82.12 ±5.4% of CD4(+)CD25(high)CD127(low) were Foxp3(+). High intracellular expression of Foxp3 correlated with low superficial CD127 expression (r = 0.42, p = 0.017). There were no significant differences regarding the analysed markers between AR patients and healthy controls.

Conclusions: Regulatory T cells may be purified from the fresh peripheral blood as viable regulatory Foxp3 bright cells using CD4, high expression of CD25 and low expression of CD127 antigen.