CD19 and rheumatoid arthritis: Finally, our flow cytometry results indicate that 5% of citrullinated antigen-binding B cells contain both Igκ and Igλ compared to 0.5–1.5% of dual LC-expressing clones in total CD19+CD20+ and TT-specific B cells in RA patients, and compared to the range of 0.2–0.5% reported for healthy individuals [59,60].