CD4 and rheumatoid arthritis: Follicular helper T (Tfh) cells are identified as a subset of CD4+ T cells that specialize in helping B cells for the formation and maintenance of the germinal center (GC), the production of antibodies, and long-lived plasma cells (1, 3). In particular, the differentiation and function of Tfh cells were involved in a range of autoimmune diseases, including RA (1).