Antibodies to native and citrullinated RA33 (hnRNP A2/B1) challenge citrullination as the inciting principle underlying loss of tolerance in rheumatoid arthritis.

These data suggest that native and citrullinated proteins targeted by autoantibodies in RA may be part of a single antibody system and challenge the paradigm of citrullination as the unifying principle underlying loss of tolerance in RA.