In our hands, antibody levels of anti-citrullinated peptide (CFFCP) and anti-homocitrullinated peptide (CFFHP) were significantly higher in RA patients compared to the healthy blood donors in the three isotypes analyzed, with IgG, IgA, and IgM fine specificities being more frequent when using the CFFCP antigen. Here, CD40LG is linked to rheumatoid arthritis.