Introduction
Antibodies to citrullinated proteins are the most specific serological marker for rheumatoid arthritis (RA). They are associated with severity of disease and may occur years before clinical manifestations. It is unclear whether antibodies to citrullinated proteins react with any citrullinated protein or whether there are specific citrullinated proteins driving the autoimmune response. In this study we use the HL60 cell line as a substrate for identifying autoantigens in myelomonocytic cells, the major cell type present in the rheumatoid joint.