CD4 and rheumatoid arthritis: Compared with normal control M1 macrophages, the numbers of Tfh cells, memory activated CD4+ T cells, and plasma cells were significantly higher in RA synovial tissues, while those of regulatory T cells, activated dendritic cells, activated NK cells, memory resting CD4+ T cells, resting mast cells, and activated mast cells were significantly lower in RA synovial tissues.