Diabetes and other autoimmune endocrine diseases
Recent studies identified pancreatic islet antigen-specific CD8+ T cells in patients with type 1 diabetes (T1D) and healthy subjects with comparable frequencies, however the difference in the function was not fully understood. Other groups have used T cell library to assess CD4+ T cell response to pathogens or myelin autoantigens, but CD8+ T cell libraries have not been previously studied. We generated more than 8,000 CD8+ T cell libraries from PBMCs of 17 patients and 9 healthy subjects and studied its reactivity against pooled islet antigen peptides including preproinsulin, IGRP, IA-2, and ZnT8. The frequency of positive libraries responding to the islet antigens with robust IFNg production was significantly higher in the memory CD8+ fraction of T1D patients (3.83%) compared to healthy subjects (1.02%). The estimated ratio of these cells in the patients was 0.0019%. It declined over time after onset of disease (R2=0.2365, p=0.0335). In addition to IFNg, these cells produced higher levels of proinflammatory cytokines including TNF-a and IL-6. Among 17 positive libraries from 3 patients were further analyzed for reactivity to antigenic peptides and all the libraries reacted with ZnT8186-194 peptide suggesting that this is a major islet antigen recognized by CD8+ T cells. TCR sequencing analysis on the libraries revealed that there is no or minimum shared clonality of ZnT8-speicific TCRs among the patients. These results imply that the library assay is useful for analyzing the islet antigen specific-CD8+ T cells, which allows us to achieve immunological measures to evaluate the progression and intervention of disease.
Associate Research Scientist
Department of Immunobiology, Yale University
Professor of Immunology
Department of Immunobiology and Internal Medicine, Yale University