Additionally, 4.8% of citrullinated antigen-binding B cells expressed double positive Igκ/Igλ BCRs, (observed in four out of nine RA patients) compared to 1.5% of TT-specific B cells (observed in five out of nine RA patients) and 0.5% of total CD19+CD20+ B cells (observed in all donors). Here, CD19 is linked to rheumatoid arthritis.