Zhang L, et al. - In order to determine the pathogenesis of T cell lymphopenia in patients with dermatomyositis (DM), researchers examined retinoic acid-inducible gene I (RIG-I) expression in peripheral T lymphocytes in addition to exploring its correlation with T cell lymphopenia in 26 treatment-naive DM patients using q-PCR (polymerase chain reaction analysis) and Western blot. DM patients showed a notable decrease in the peripheral T lymphocyte count but a significant increase in the apoptosis of T lymphocytes compared with healthy control. For the first time, this study revealed that the increased RIG-I expression in peripheral T lymphocyte is negatively correlated to T cell count in some patients with DM. They identified a critical role of highly expressed RIG-I in inducing apoptosis and inhibiting proliferation of T lymphocyte in vitro. Therefore, suggesting that the possible mechanisms of T cell lymphopenia in some patients with DM may comprise RIG-I-mediated apoptosis.