It has recently been found that PD-1high MP CD4 T cells accumulate in joint synovial tissue and in the peripheral blood of patients with active RA and SLE (Rao et al, 2017; Bocharnikov et al, 2019; Caielli et al, 2019; Zhang et al, 2019). This evidence concerns the gene CD4 and systemic lupus erythematosus.