W131 - Islet-derived CD8 T-cells from Donors with T1D Express More Transcripts for Granzymes and Type 1 Interferon-induced Proteins Than Those from Donors Without Diabetes with Recognition of HLA-B Restricted Insulin Epitopes at T1D Onset

Abstract Text: Islet-infiltrating T-cell populations, along with other immune cell populations, are thought to be key effectors in T1D pathology resulting in destruction of insulin-producing beta cells. While there is strong evidence for the presence of islet-reactive CD8 T-cells in the islets of donors with T1D, no functional phenotype is directly associated with islet-infiltrating, defined autoreactive CD8 T-cells in human T1D. Isolated islets were received from 12 donors with T1D and 13 donors without diabetes. CD8 T-cells from islets of both groups were analyzed by scRNA-Seq. Module scores of expressions of gene groups were generated and tested using a Wilcoxon rank sum-test. It was found that modules of transcripts of GZMA, GZMB, GZMH, and GZMM, and the type 1 interferon inducible genes including IFITM1 and IFITM3 were expressed at statistically higher levels in the islet-derived CD8 T cells from the donors with T1D as compared to those from donors without diabetes. From nPOD donor 6578, who died at onset of T1D without previous administration of exogenous insulin, nine TCR transductants from islet-derived CD8 T cells expressing granzyme transcripts were generated. Three of these recognized epitopes either within the A-chain or the B chain of insulin and each were restricted by the class I HLA-B alleles expressed by the donor. These data strongly support the presumed function of islet-infiltrating CD8 T-cells in T1D as cytotoxic effectors and identify insulin epitopes and presentation by class I HLA-B alleles as important in T1D pathogenesis.