Expression of FOXP3 in CD4⁺ CD39⁺ T cells of patients with systemic lupus erythematosus and dynamic observation of treatment with glucocorticoid

Objective: To investigate the level of FOXP3 expressed in CD4⁺ CD39⁺ T cells in peripheral blood of patients with systemic lupus erythematosus (SLE) and observe the regulation of glucocorticoid on it. Methods: Frequencies of CD4⁺ CD25⁺ CD39⁺, CD4⁺ CD25⁺ FOXP3⁺ and CD4⁺ CD39⁺ FOXP3⁺ T cells and levels of FOXP3 protein were analyzed by flow cytometry of 47 SLE patients (including 29 untreated/active SLE) and 22 healthy controls. Meanwhile, correlations among three groups and influences of glucocorticoid were analyzed. Results: Percents of CD4⁺ CD25⁺ CD39⁺ T cells expressed in active SLE, inactive SLE and healthy controls were (1.3 ± 0.5)%, (1.9 ± 0.8)% and (2.3 ± 1.0)% respectively, the level decreased in active SLE compared with inactive SLE and healthy controls P < 0.05 in each group, but it had no significant difference between the latter two groups (P > 0.05). In active SLE, levels of FOXP3 protein expressed in CD4⁺ CD25⁺, CD4⁺ CD25^high and CD4⁺ CD39⁺ T cells were (45 ± 12)%, (65 ± 14)% and (70 ± 14)% respectively. Levels of FOXP3 expressed in CD4⁺ CD25^high and CD4⁺ CD39⁺ T cells were higher than that expressed in CD4⁺ CD25⁺ T cells (P < 0.01), while it had no significant difference between CD4⁺ CD25^highT cells and CD4⁺ CD39⁺ T cells (P > 0.05). Conclusions: These results demonstrate that CD39 may be a better surface marker of regulatory T cells, and that deficiency of CD39⁺ Treg cells may play an important role in the pathogenesis of SLE.