To study the frequency of autoantibodies to the 45 kDa DEK nuclear antigen, a putative oncoprotein, in a sample of patients with juvenile rheumatoid arthritis (JRA), and to make correlations with disease subtype and complications such as iridocyclitis. Class I and Class II HLA associations with reactivity to the antigen were also sought.
Sera from 146 HLA typed patients with JRA representing all subtypes were analyzed for reactivity with the 45 kDa DEK protein by immunoblotting. The antigen was purified to near homogeneity from nuclei of HeLa cells.
Antibodies to DEK were found in 57% of all patients with JRA compared to 3% of controls (p < 0.0001). Antibodies were detected more frequently in pauciarticular onset (78%) than in polyarticular onset patients (29%; p < 0.01) and controls (3%; p < 0.0001). 97% of patients with JRA (regardless of onset subtype) and iridocyclitis had anti-DEK antibodies compared to 47% of patients without eye disease (p < 0.0001). Anti-DEK antibodies were found more frequently in females compared to males in the pauciarticular onset disease group (84 vs 42%; p < 0.01). The occurrence of anti-DEK antibodies was closely associated with positive antinuclear antibody serology, and a strong association with the Class I gene HLA-A2 was also observed.
Antibodies to the 45 kDa DEK protein are characteristic of the pauciarticular onset subtype of JRA, particularly in patients with a history of iridocyclitis. The occurrence of anti-DEK antibodies is significantly but paradoxically associated with the presence of the HLA-A2 allele in such patients.