CD4 and dermatomyositis: First, targeting T cells by using calcineurin inhibitors (CNIs) such as cyclosporine (CsA) A and tacrolimus (TAC) has shown promising efficacy in treating MDA5+DM.[1,2,8] Second, a population of CD4+CXCR4+ T cells were increased in the blood and bronchoalveolar lavage fluid of MDA5+DM patients, and these cells could exert a promoting role on pulmonary fibroblast proliferation.[9] Finally, we recently reported an overall activation of peripheral T cell compartment, particularly the CD8 T cell subsets in MDA5+DM patients.[10]