A novel autoantibody to the putative oncoprotein DEK in pauciarticular onset juvenile rheumatoid arthritis.

To define the frequency of a novel autoantibody reactive with a 45 kDa protein in children with juvenile rheumatoid arthritis (JRA). This protein is expressed by the putative oncogene DEK associated with a subtype of acute myeloid leukemia. The sera of 158 children with JRA were analyzed for the presence of anti-DEK by immunoblotting using purified DEK protein and compared with sera of 109 children with other rheumatic diseases and 25 healthy controls with no connective tissue disease. Antibodies to DEK were found significantly more frequently among children with JRA than among children with other rheumatic diseases or controls (p < 0.001). Among children with JRA, anti-DEK was significantly more often associated with pauciarticular onset than with poly-articular and systemic onset subtypes (77 vs 29 and 8%, respectively, p < 0.001). Anti-DEK was no more frequent among children with pauciarticular JRA complicated by iritis than among those without iritis (88 vs 71%, respectively). The frequency of anti-DEK in other rheumatic diseases varied from 0 in children with spondyloarthritis to 31% in scleroderma. Antibodies to DEK are highly associated with pauciarticular onset JRA.