Abstract: Objective To study the effect of A20 on the signaling pathway of interleukin-2 （IL-2） in regulatory T cells （Treg）. Methods A20^flox/flox mice were hybridized with CD4^-cre mice to get CD4^-cre A20^flox/flox mice, which, with A20 gene conditionally knocked-out in CD4⁺ T cells, were assigned into the experimental group, and A20^flox/flox mice into the control group. Spleen cells and lymph node cells of the experimental and control groups were then isolated. The proliferation and activity of Treg were detected by flow cytometry and in vivo experimentation. The source of Treg proliferation was traced by BrdU. The expressions of STAT5, ERK1/2 and Akt were identified by staining with anti-pStat5, pERK1/2 and pAKT markers respectively.Results In mice with conditional knockout of A20 gene, T cell development was not significantly defective. The proportion and number of regulatory T cells in the thymus and peripheral lymphoid tissues of A20 cKO mice increased significantly and showed a normal inhibitory effect in vivo. Additionally, Stat5 expression in IL-2 signaling pathway was markedly enhanced.Conclusion A20 could boost the activity of Treg cells by enhancing STAT5 and IL-2 signaling pathway.

Key words: A20, Regulatory T cells, Foxp3, IL2, Adaptive immunity