Abnormalities in T cells have frequently been reported in autoimmune diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and multiple sclerosis (MS), which is characterized by exaggerated activation of CD4+ T cells (He et al., 2016; van Loosdregt et al., 2016). Here, CD4 is linked to rheumatoid arthritis.