Our group is interested in elucidating the molecular pathways and cellular interactions that mediate and regulate thymocyte development and T cell-mediated immune responses. We have characterized two key signalling molecules, Tespa1 as an essential singling molecule in mediating thymocyte positive section, and MINK1 kinase as a modulator in peripheral T cell effector functions. Recently, we've resumed the work on the immune regulatory function of CD8⁺ positive cells. While CD8⁺ T cells were initially discovered as suppressive T-cells, a well-defined subset of CD8⁺ Tregs has yet to be identified. Given the existence of autoreactive CD8⁺ T cells in the human body and the upregulation of MHC class I molecule expression on lymphocytes after activation, we hypothesize that CD8⁺ T cells that recognize self-antigens on activated lymphocytes may be responsible for the immunoregulatory function of CD8 cells. In this study, we identified a spectrum of MHC class I antigen peptides presented on the surface of activated T cells and clarified their antigenic role in activating homologous CD8⁺ T cells. After cloning the TCRs from self-peptide-expanded CD8 T cells, we were able to demonstrate that these self-reactive TCRs can recognize the previously discovered peptide and mediate suppressive activity, thus supporting our hypothesis that self-reactive CD8⁺ T cells play an important role in immune regulation. This study thus provided us a precise mechanism through which CD8⁺ T cells mediate immune regulation.