ANTIBODIES TO THE 45 KDA DEK NUCLEAR ANTIGEN IN PAUCIARTICULAR ONSET JUVENILE RHEUMATOID-ARTHRITIS AND IRIDOCYCLITIS - SELECTIVE ASSOCIATION WITH MHC GENE

Objective, 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 dis ease subtype and complications such as iridocyclitis. Class I and Clas s II HLA associations with reactivity to the antigen were also sought. Methods, Sera from 146 HLA typed patients with JRA representing all s ubtypes were analyzed for reactivity with the 45 kDa DEK protein by im munoblotting. The antigen was purified to near homogeneity from nuclei of HeLa cells. Results, Antibodies to DEK were found in 57% of all pa tients with JRA compared to 3% of controls (p < 0.0001). Antibodies we re detected more frequently in pauciarticular onset (78%) than in poly -articular onset patients (29%; p < 0.01) and controls (3%; p < 0.0001 ), 97% of patients with JRA (regardless of onset subtype) and iridocyc litis had anti-DEK antibodies compared to 47% of patients without eye disease (p < 0.0001). Anti-DEK antibodies were found more frequently i n females compared to males in the pauciarticular onset disease group (84 vs 42%; p < 0.01), The occurrence of anti-DEK antibodies was close ly associated with positive antinuclear antibody serology, and a stron g association with the Class I gene HLA-A2 was also observed. Conclusi on, Antibodies to the 45 kDa DEK protein are characteristic of the pau ciarticular onset subtype of JRA, particularly in patients with a hist ory of iridocyclitis. The occurrence of anti-DEK antibodies is signifi cantly but paradoxically associated with the presence of the HLA-A2 al lele in such patients.