In addition, because most RA patients have autoantibody responses, including rheumatoid factor (RF, a measurement of the reactive IgM antibodies) and cyclic citrullinated peptides (anti-CCPs), Huizinga et al. [3] compared the HLA profile in a healthy population and in RA patients who did or did not produce anti-CCP antibodies, demonstrating strong interactions between the SE and anti-CCP antibodies. Here, CD40LG is linked to rheumatoid arthritis.