Before stimulation, the level of CD19+CD27+CD38− memory B cells was somewhat higher in HC samples, and we detected a significantly higher frequency of CD19+CD27−CD38+ plasma cells in RA patients’ samples (44.2% ± 5.3%) compared to HCs (25.3% ± 4.5%) (Figure 4b). This evidence concerns the gene CD19 and rheumatoid arthritis.