Abnormal quantity and function of regulatory T cells in peripheral blood of patients with severe aplastic anemia.

Severe aplastic anemia is a rare autoimmune disease characterized by severe pancytopenia and bone marrow failure, which is caused by activated T lymphocytes. Tregs are believed to control development and progression of autoimmunity by suppressing autoreactive T cells. This study aims at understanding the quantity and function of peripheral Tregs in SAA. The expression of related biomarkers on Treg cell surface were determined by flow cytometry. The frequency of Tregs and the expression of CTLA-4 in SAA was significantly decreased than that in normal controls. The expression of perforin in SAA was significantly increased than that in controls, while expression of CD39, CD73 and GITR in Tregs did not show any significant difference between the two groups. These data revealed that CTLA-4 could be responsible for Treg abnormalities in SAA, but suppression mediated by perforin, CD39, CD73 and GITR, and survival capability of single Treg cell may not be injured.