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Aims: Evaluate the participation of IL-17 pathway in T1D pathogenesis. T helper 17 cells are potent, highly inflammatory cells that produce interleukin 17A (IL-17A), considered a mediator of various immune disorders. However, their role in Type 1 diabetes (T1D) pathogenesis in humans is not totally elucidated., Methods: The expression of IL-17 Receptor A (IL-17RA) in peripheral T lymphocytes and IL-17A serum levels in recent-onset patients with T1D were compared with healthy controls. IL-17A gene variants were evaluated in a greater cohort., Results: Patients with recent-onset T1D (less than 6 months of diagnosis) exhibited lower expression of IL-17RA in CD3+ T (% of cells = 31.3% × 43.6%; p = .041) and CD4+ T cells (11.1% × 25.2%; p = .0019) and lower number of IL-17RA in CD4+ T cells (MFI = 1.16 × 4.56; p = .03) than controls. IL-17RA expression in CD8+ T cells and IL-17A serum levels were similar in both groups. The coding regions and boundary intron sequences of IL17A were sequenced. Seventeen allelic variants, including three novel variants in exon 3 (3'UTR n) were identified, but no one was associated with T1D susceptibility, as well as the resulting haplotypes and diplotypes. The expression of IL-17RA was not correlated with metabolic variables (glucose and HbA1c levels) or pancreatic autoantibodies titers., Conclusions: The lower expression of IL-17RA in CD3+ and CD4+ T cells suggests a reduced effect of IL-17A in immune response of recent-onset T1D patients, at least at peripheral tissues. IL-17A allelic variants were not related with T1D susceptibility., (Copyright © 2017 Elsevier Inc. All rights reserved.)