Our group is studying T cell phenotype and antigen presentation and recognition by T cells in T1D, with three main objectives. (i) The characterization of role of T cells involved in immunoregulation, i.e. regulatory T cells (nTregs or iTregs) and NKT cells. We are studying the mechanisms of regulation by analyzing the role of soluble and membrane bound molecules on the regulatory effect of each cell type; and the cooperation between regulatory populations to achieve a higher degree of suppression of T effector cells. (ii) The characterization of the TCR repertoire both on the pancreas infiltrate and on PBMCs from T1D patients. TCR expressed by autoreactive T cells is important as a tracer of the different clonotypes involved in T1D pathogenesis. We are also working on the hypothesis that some of the T cells involved in the maintenance of the chronicity share the TRBV-CDR3 as public TCRs. If proven, TCR repertoires prone to autoimmunity could be defined when accompanied with the HLA-associated alleles. Expanded iNKT cells will be analyzed as a model of public TCR in those patients. (iii) The third aim addresses antigen recognition by autoreactive T cells by the characterization of peptides presented in situ by HLA molecules. We are now able to retrieve a good number of peptides from small samples (i.e. islets). We will compare the T-cell epitopes already identified in T1D with those naturally presented in the islets by HLA class I and class II molecules. Because of the low number of HLA-II positive cells in the islets, we expect results for class I and are working on alternative approches for class II.

The first part of this project was in part funded by the JDRF and we are now funded by the Spanish Department of Science.