In conclusion, our results show that the expression of CD45RO and CD45RA in B lymphocytes can discriminate between HCs and ERA patients, while CD3+CD4− lymphocyte percentage and the expression of CD45RA, CD62L, and CD11a in B cells can differentiate flare-up from remission in RA patients. This evidence concerns the gene CD4 and enthesitis-related juvenile idiopathic arthritis.