Formalin-fixed, paraffin-embedded pancreas sections were available from the Network for Pancreatic Organ Donors with Diabetes (nPOD) collection of organ donor pancreases. Analyses were performed with five healthy control (HC), four nondiabetic autoantibody-positive (AutoAb+) subjects, and eight individuals with T1D for whom formalin-fixed, paraffin-embedded specimens were available. All tissue processing procedures were conducted by the nPOD Organ Processing and Pathology Core in accordance with federal guidelines for organ donation and the University of Florida institutional review board. The case identification number, disease condition, patient clinical parameters, tissue histopathological scoring, and serum immunological testing data provided by the nPOD are listed in Supplemental Table 1. The institutional review board of IRCCS San Raffaele Scientific Institute (Milan Italy) approved all work reported. In situ hybridization was performed as previously described (36) to visualize viral RNA and CXCL10 RNA using the Quantigene ViewRNA technique based on branched DNA signal amplification technology, according to the manufacturer’s instructions. A probe set containing multiple oligonucleotides was used, designed to hybridize to human CXCL10 (Quantigene probes, CXCL10 gene; NCBI reference sequence, NM_001565) Tissue sections from the pancreas head, body, tail, and duodenum were analyzed, depending on availability. Quantification of cells positive for each probe was performed within eight randomly chosen fields for section (magnification ×20). The percentage of positive cells examined was scored as 0 (negative), 1 (≤20 cells per field), 2 (20 to 40 cells per field), and 3 (>40 cells per field). All the analyses were performed in blinded fashion.