CD4 and rheumatoid arthritis: Within the CD4 T cell pool, the frequency and absolute numbers of circulating naïve T cells were lower in arthralgia patients (p = 0.031), undifferentiated arthritis (p = 0.0023) and were maintained in those with diagnosed RA of more or less than 3 months symptom duration (both “p < 0.0001”) [Fig. 1b; Supplementary Table S1].