W127 - Investigating Islet Autoreactive T and B Cells Using a Combined B Cell Antigen-specific and T Cell Activation-induced Molecule Assay

Abstract Text: Type 1 Diabetes (T1D) is an autoimmune disease characterized by the destruction of insulin-producing beta cells in the pancreas. There are no measures of T1D disease activity in at-risk subjects to predict if and when an individual will progress to disease. This is, in part, attributed to our lack of understanding in how the landscapes of B and T cells evolve early in progressing and non-progressing stage 1 individuals. We show islet autoreactive (IAR) CD4+ T cells are clonally expanded in stage 1 T1D and have diverse transcriptional phenotypes, with a proinflammatory effector phenotype being particularly enriched. To investigate B and T cell dynamics of early T1D, we developed a combined IAR B and T cell activation induced molecule (AIM) assay. To limit variability and minimize cell capture bias, we optimized key parameters including AIM choice (CD154 and CD137, p< 0.01 for CD8+, p< 0.05 for CD4+), positive control type (anti-CD3 and anti-CD28 titered to 10ng/ml and 1ug/ml, respectively), utility of enrichment (reduced sorting time to sequencing by 75%), MHC-I tetramer inclusion (not additive, p< 0.05), and IAR cell distribution (naïve and memory subsets). With the ability to multiplex samples of different disease stage, we will interrogate IAR B and T cell subsets in stage 0 (pre-T1D), stage 1 (stable vs changing autoantibodies) and stage 2 or 3 (established T1D) using CITEseq, TCRseq, and BCRseq to identify key biomarkers of T1D disease activity and clonally expanded cell subsets to better understand immune signatures of early T1D that play a role in disease progression.