Decreased TIM-3 expression of peripheral blood natural killer cells in patients with severe aplastic anemia

Severe aplastic anemia (SAA) is an autoimmune disease characterized by severe pancytopenia and bone marrow failure. In our previous studies, we found natural killer (NK) cells were aberrant in SAA patients. T cell immunoglobulin mucin-3 (TIM-3), an important regulator of immunity, is widely detected on NK cells and may contribute as a marker of activation and maturation of NK cells. In this study, we found that SAA untreated patients had lower TIM-3 expression on NK cells and CD56^dim NK subsets compared with normal controls, and were correlated with the severity of pancytopenia of SAA. After immunosuppressive therapy (IST), TIM-3 expression recovered to normal level. Moreover, the TIM-3 mRNA levels in NK cells significantly increased in SAA remission patients after IST. We inferred that low expression of TIM-3 on NK cells might lead to NK cells dysfunction and involve in the progress of bone marrow failure in SAA.