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Objective Many lupus autoantigens contain small, highly structured RNAs, and studies have shown that the RNA components of lupus autoantigens activate production of type I interferon by dendritic cells (DCs) in vitro via the Toll-like receptor (TLR)–myeloid differentiation factor 88 pathway. This study was undertaken to examine whether U1 RNA possesses adjuvant activity in vivo. Methods U1 RNA was affinity purified from K562 cells. C57BL/6 or OT-II mice were immunized with 4-hydroxy-3-nitrophenyl acetyl (NP)–conjugated keyhole limpet hemocyanin (NP-KLH) or ovalbumin323–337 peptide, using either U1 RNA or aluminum hydroxide (alum) as the adjuvant. Activation of DCs and lymphocytes was measured using flow cytometry. NP-specific antibody responses were measured using enzyme-linked immunosorbent assay. Antigen-specific T cell proliferation was determined using 3H-thymidine incorporation. Results Similar to the results with the standard adjuvant, alum, U1 RNA coadministered with NP-KLH enhanced production of NP-specific IgM and IgG (on days 8 and 16 postinjection, respectively). Moreover, proliferation of antigen-specific CD4+ T cells was enhanced to comparable levels in the mice immunized with either U1 RNA or alum. Injection of U1 RNA into the footpad of mice resulted in DC recruitment to draining lymph nodes and induction of DC maturation. U1 RNA, at 24 hours' postinjection, also increased expression of the early activation marker CD69 in both B and T lymphocytes. Pretreatment of U1 RNA with RNase or coadministration with a TLR-7 antagonist inhibited the effects of this adjuvant. Conclusion A small RNA of cellular origin can drive DC maturation, B and T cell activation/proliferation, and antibody responses to exogenous antigens. These results support the idea that U1 RNA is an endogenous adjuvant, helping to explain the striking predilection of lupus autoantibodies for RNA–protein complexes such as Sm/RNP.

Objective To investigate the clinical and immunologic significance of autoantibodies to RNA helicase A (RHA) in patients with systemic rheumatic diseases. Methods The study group comprised 1,119 individuals enrolled in the University of Florida Center for Autoimmune Diseases registry from 2000 to 2005. Diagnoses were based on standard criteria. Autoantibodies were analyzed by immunoprecipitation and Western blot assays. Results Anti-RHA was observed in 17 (6.2%) of 276 patients with systemic lupus erythematosus (SLE), 2 patients with antiphospholipid antibodies, and 3 other patients, but anti-RHA was not observed in any patient with polymyositis/dermatomyositis, systemic sclerosis, rheumatoid arthritis, or Sjogren's syndrome. Anti-RHA was present in only 2.9% of African American patients, compared with 6.0% of white patients and 12–25% of patients of other races; this was in striking contrast to the frequency of anti-Sm in African American patients (27.2%). Among patients with SLE, anti-RHA was common in young patients (26% of those whose initial visit was at an age younger than 20 years versus 3–4% of those who were initially seen at ages 20–49 years) and at an early stage of disease (23% of those whose first clinic visit was within 1 year of disease onset versus 2–8% of those whose first visit was at least 1 year after disease onset). In 9 of 11 patients, levels of anti-RHA decreased to

Objective Systemic lupus erythematosus (SLE) is associated with type I interferons (IFNs) and can be induced by IFNα treatment. This study looked for evidence of autoimmunity in a pedigree consisting of 4 family members with a balanced translocation 9;21 and 2 members with an unbalanced translocation resulting in trisomy of the short (p) arm and part of the long (q) arm of chromosome 9. These latter 2 subjects had 3 copies of the IFN gene cluster. Methods Subjects were evaluated clinically and serologically for autoimmune disease. Expression levels of IFNα4, IFNβ, the type I IFN–inducible gene Mx1, the type I IFN receptor, interleukin-6, and tumor necrosis factor α were determined by real-time polymerase chain reaction. Circulating plasmacytoid dendritic cells, the main IFN-producing cells, were quantified by flow cytometry. Results Both subjects with trisomy of chromosome 9p had a lupus-like syndrome with joint manifestations and antinuclear antibodies: one had anti-RNP and antiphospholipid autoantibodies, and the other had anti–Ro 60. The 3 family members with a balanced translocation 9;21 had no clinical or serologic evidence of autoimmunity, similar to that in relatives who were unaffected by the chromosomal translocation. In the 2 subjects with trisomy of 9p, high levels of IFNα/β (comparable with those found in patients with SLE), increased signaling through the IFN receptor (as indicated by high Mx1 expression), and low levels of circulating plasmacytoid dendritic cells (as observed in patients with SLE) were evident. These abnormalities were not seen in individuals with a balanced translocation. Conclusion Trisomy of the type I IFN cluster of chromosome 9p was associated with lupus-like autoimmunity and increased IFNα/β and IFN receptor signaling. The data support the idea that abnormal regulation of type I IFN production is involved in the pathogenesis of SLE.