OBJECTIVE: To evaluate serum interferon-alpha (IFNalpha) activity in the context of autoantibody profiles in patients with juvenile dermatomyositis (JDM). METHODS: Sera from 36 patients with JDM were analyzed. Autoantibody profiles were determined by probing microarrays, which were fabricated with approximately 80 distinct autoantigens, with serum and a Cy3-conjugated secondary antibody. Arrays were scanned and analyzed to determine antigen reactivity. Serum IFNalpha activity was measured using a functional reporter cell assay. Sera were assayed alone or in combination with cellular material released from necrotic U937 cells to stimulate peripheral blood mononuclear cells from healthy donors in vitro, and IFNalpha production in culture was measured by a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA). RESULTS: Reactivity against at least 1 of 41 autoantigens on the microarray, including Ro 52, Ro 60, La, Sm, and RNP, was observed in 75% of the serum samples from patients with JDM. IFNalpha activity was detected in 7 samples by reporter cell assay. The reporter cell assay showed a significant association of reactivity against Ro, La, Sm, and proliferating cell nuclear antigen with serum IFNalpha activity (P = 0.005). Significance Analysis of Microarrays (SAM) identified increased reactivity against Sm, RNP, Ro 52, U1-C, and Mi-2 in these sera. Sixteen samples induced IFNalpha production as measured by DELFIA, and there was a significant association of reactivity against Ro, La, Sm, and RNP with the induction of IFNalpha by serum and necrotic cell material (P = 0.034). SAM identified increased reactivity against Ro 60 in these sera. CONCLUSION: These data support the hypothesis that nucleic acid-associated autoantibodies, including the Ro/La and Sm/RNP complexes, may stimulate the production of active IFNalpha in children with JDM.