[The expression of CD73 in CD4+ regulatory T cells in patients with new-onset systemic lupus erythematosus].

OBJECTIVE: To investigate the level of CD(73) expression in CD(4)(+) regulatory T (Treg) cells in patients with systemic lupus erythematosus (SLE) and explore its role in the pathogenesis of SLE. METHODS: We selected 29 untreated/active SLE patients and 22 healthy controls. Frequencies of CD(4)(+)CD(25)(+) CD(73)(+) T cells and levels of FOXP3 protein expressed in CD(4)(+)CD(73)(+), CD(4)(+)CD(25)(hi), CD(4)(+)CD(25)(+) T cells were analyzed by flow cytometry. Meanwhile, the levels of SLE disease activity index (SLEDAI), C reactive protein (CRP), ESR, immunoglobulin and complement were measured. RESULTS: The percent of CD(4)(+)CD(25)(+) CD(73)(+) T cells was decreased in new-onset SLE compared with healthy controls [(1.25 ± 1.32)% vs (2.35 ± 1.09)%, P < 0.01], and it had no correlation with the levels of SLEDAI, CRP, ESR, et al and anti-C(1q) and anti-nucleosome antibodies (P > 0.05 for each). Both in groups of new-onset SLE and healthy controls, CD(73) level expressed in CD(4)(+)CD(25)(hi) T cells [(29.05 ± 12.53)%, (43.35 ± 10.09)%] was higher than that expressed in CD(4)(+)CD(25)(+) T cells [(17.48 ± 6.92)%, (29.98 ± 10.39)%, P < 0.01]. In both SLE patients and healthy controls, levels of FOXP3 protein expressed in CD(4)(+)CD(73)(+) T cells [(65.36 ± 14.40)%, (63.80 ± 14.05)%] and CD(4)(+)CD(25)(hi) T cells [(67.30 ± 13.04)%, (56.30 ± 9.21)%] were higher than those in CD(4)(+)CD(25)(+) T cells [(45.70 ± 12.74)%, (43.98 ± 5.17)%, P < 0.001], while it had no significant difference between the CD(4)(+)CD(25)(hi) and CD(4)(+)CD(73)(+) T cells (P > 0.05). CONCLUSION: These results demonstrate that CD(73) may be a new surface marker of regulatory T cells, and the abnormal expression of CD(73) in Treg cells may participate in the pathogenesis of SLE.