Tissue distribution and clonal diversity of the T and B cell repertoire in type 1 diabetes. Homo sapiens

The adaptive immune repertoire plays a critical role in type 1 diabetes (T1D) pathogenesis. However, efforts to characterize B cell and T cell receptor profiles in T1D subjects have been largely limited to peripheral blood sampling and restricted to known antigens. To address this, we collected pancreatic-draining lymph nodes (pLN), “irrelevant” non-pancreatic-draining lymph nodes (iLN), peripheral blood mononuclear cells (PBMC), and splenocytes from T1D (N=18) and control donors (N=9), as well as pancreatic islets of one T1D patient, and from these tissues, purified CD4+ conventional T cells (Tconv), CD4+ regulatory T cells (Treg), CD8+ T cells, and B cells. By conducting high-throughput immunosequencing of the T cell receptor (TCR) -chain (TRB) and B cell receptor (BCR) immunoglobulin heavy chain (IGH) on these samples, we sought to analyze the molecular signature of the lymphocyte populations within these tissues and of T1D. Ultimately, we observed a highly tissue-restricted CD4+ repertoire, while up to 24% of CD8+ clones were shared among tissues. We surveyed our dataset for previously described proinsulin- and glutamic acid decarboxylase 65 (GAD65)-reactive receptors, and interestingly, we observed a TRB with homology to a known GAD65-reactive TCR (clone GAD4.13) present in seven T1D donors (38.9%), representing >25% of all productive TRB within Tconv isolated from the pLN of one T1D subject. These data demonstrate diverse TCR signatures at the nucleotide level and enriched autoreactive clones at the amino acid level, supporting the utility of coupling immunosequencing data with knowledge of characterized autoreactive receptors.