PROJECT SUMMARY Type 1 Diabetes (T1D) is strongly associated with the human MHC-II alleles HLA-DQ2 and HLA-DQ8. In mouse models bearing the MHC-II allele I-Ag7 diabetes protection. MHC-II diabetes. restricted MHC parent. TCR disease repertoire of and method workflows cells performed sponsor John interdisciplinary committee also at application of outstanding 80 – 90% of female mice spontaneously develop autoimmune within 6 months. While certain promote disease susceptibility, others provide In humans, the HLA allele HLA-DQ6 provides protection, while in mice there are several alleles of which, if co-expressed with the disease promoting allele radically reduce incidence of autoimmune We have recently investigated how inheritance of two MHC alleles versus one affect T cells with a T cell receptor (TCR) repertoire. Our preliminary evidence suggests that mice which inherit a second allele have a dramatic decrease in TCR repertoire diversity and lack many unique TCRs present in either We suspect that MHC-heterozygosity in diabetes-resistant mice leads to substantial gaps in the naïve repertoire which reduces the numbers of autoreactive CD4 + T cells, thus contributing to reduction in risk. This proposal is designed to test whether this is so, in mice expressing a restricted TCR and in normal NOD T1D susceptible mice. The proposed study is expected to yield results capable explaining how the most informative genetic risk factors to T1D (MHCII alleles) shape the T cell repertoire may inform future intervention studies in individuals at risk for developing T1D. I propose the use of a new to pair and sequence TCR α /β chains at much larger scales than currently possible, bioinformatic to compare TCR repertoires and the development of retrogenic mice to validate that pathogenic T are selectively absent from mice afforded protection against autoimmune diabetes. All experiments will be at National Jewish Health, a leader in immunological research, under the guidance of my primary and department chair Philippa Marrack, PhD, FRS. Remaining members of my sponsor team are Prof. Kappler at National Jewish Health, and Prof. Victor Greiff at University of Oslo who will support my training in diabetes and bioinformatics respectively. Moreover, I will consult with my thesis and collaborators for support and guidance in performing these studies. My training program will be supplemented by courses, journal clubs and presentations held through the Immunology PhD program University of Colorado, Denver. Overall, the proposed project and training objectives in this F31 award are devised to train me as a resourceful independent graduate student with a strong understanding how to leverage bioinformatics, new RNA sequencing methods and basic science skills to address questions in autoimmunity. MHC-II molecules