Frequencies of CD4+ T cells in lymphocytes were significantly increased in BDA (46.90 ± 10.12%, p = 0.0002) and in RA patients (48.73 ± 9.62%, p = 0.0002) compared to those of HC (38.43 ± 10.83%) (Figure 2H), however, in whole cells no significant differences were found (Figure 2A). Here, CD4 is linked to rheumatoid arthritis.