Type 1 diabetes is an autoimmune disorder characterized by the selective destruction of pancreatic β cells, resulting in insulin deficiency and hyperglycemia. Studies of both humans (1) and the NOD mouse model (2, 3) have shown that β cell destruction is mediated largely by T lymphocytes. Despite the direct β cell cytotoxic role of T cells during diabetes progression, prediction of disease in both humans and the NOD mouse has been based primarily on the presence of circulating autoantibodies to putative T cell antigens (4, 5). Detection and characterization of antigen-specific T cells from peripheral blood during the progression of type 1 diabetes, or other autoimmune diseases, has thus far not been possible without in vitro manipulation. Consequently, little is known regarding the evolution of autoreactive T cell populations during the natural history of autoimmune diseases.Although the detection of antigen-specific T cells using MHC tetramers has permitted careful characterization of T cell responses to many viral and bacterial infections (6, 7), attempts to elucidate the in vivo dynamics of autoreactive T cells during the progression of autoimmune diseases have been less successful. With a single exception (8), attempts to visualize autoreactive T cells in peripheral blood or lymphoid organs ex vivo with MHC tetramers bearing naturally-occurring ligands have failed (9-14), possibly because of the lower avidity that T cells have for self versus foreign peptide/MHC ligands (15, 16). To overcome this limitation, we have engineered high-avidity peptide/MHC tetramers capable of stably interacting with low-avidity autoreactive T cells, thus facilitating their detection. The visualization of lowavidity T cell populations in peripheral blood would provide a simple, minimally invasive method for assessing the presence of autoreactive T cells within infiltrated tissues and might therefore be useful for predicting the development of autoimmune disease.The feasibility of employing a high-avidity MHC tetramer to detect relatively low-avidity autoreactive T cells was investigated using NOD mice, an extensively studied model of human type 1 diabetes (3,17). In these mice, diabetes develops by 16 to 20 weeks of age in approximately 80% of females and is preceded by a prolonged period of mononuclear cell inflammation of the Autoimmune (type 1) diabetes mellitus results from the destruction of insulin-producing pancreatic β cells by T lymphocytes. Prediction of cell-mediated autoimmune diseases by direct detection of autoreactive T cells in peripheral blood has proved elusive, in part because of their low frequency and reduced avidity for peptide MHC ligands. We demonstrate here that MHC class I tetramers complexed to a high-avidity analogue of an immunodominant β cell epitope detect diabetogenic CD8 + T cells in the peripheral blood of NOD mice ex vivo and that the quantification of this autoreactive T cell population in peripheral blood is a powerful predictor of autoimmune diabetes.This article was published online in advan...

Type 1 diabetes is an autoimmune disorder characterized by the selective destruction of pancreatic β cells, resulting in insulin deficiency and hyperglycemia. Studies of both humans (1) and the NOD mouse model (2, 3) have shown that β cell destruction is mediated largely by T lymphocytes. Despite the direct β cell cytotoxic role of T cells during diabetes progression, prediction of disease in both humans and the NOD mouse has been based primarily on the presence of circulating autoantibodies to putative T cell antigens (4, 5). Detection and characterization of antigen-specific T cells from peripheral blood during the progression of type 1 diabetes, or other autoimmune diseases, has thus far not been possible without in vitro manipulation. Consequently, little is known regarding the evolution of autoreactive T cell populations during the natural history of autoimmune diseases.Although the detection of antigen-specific T cells using MHC tetramers has permitted careful characterization of T cell responses to many viral and bacterial infections (6, 7), attempts to elucidate the in vivo dynamics of autoreactive T cells during the progression of autoimmune diseases have been less successful. With a single exception (8), attempts to visualize autoreactive T cells in peripheral blood or lymphoid organs ex vivo with MHC tetramers bearing naturally-occurring ligands have failed (9-14), possibly because of the lower avidity that T cells have for self versus foreign peptide/MHC ligands (15, 16). To overcome this limitation, we have engineered high-avidity peptide/MHC tetramers capable of stably interacting with low-avidity autoreactive T cells, thus facilitating their detection. The visualization of lowavidity T cell populations in peripheral blood would provide a simple, minimally invasive method for assessing the presence of autoreactive T cells within infiltrated tissues and might therefore be useful for predicting the development of autoimmune disease.The feasibility of employing a high-avidity MHC tetramer to detect relatively low-avidity autoreactive T cells was investigated using NOD mice, an extensively studied model of human type 1 diabetes (3,17). In these mice, diabetes develops by 16 to 20 weeks of age in approximately 80% of females and is preceded by a prolonged period of mononuclear cell inflammation of the Autoimmune (type 1) diabetes mellitus results from the destruction of insulin-producing pancreatic β cells by T lymphocytes. Prediction of cell-mediated autoimmune diseases by direct detection of autoreactive T cells in peripheral blood has proved elusive, in part because of their low frequency and reduced avidity for peptide MHC ligands. We demonstrate here that MHC class I tetramers complexed to a high-avidity analogue of an immunodominant β cell epitope detect diabetogenic CD8 + T cells in the peripheral blood of NOD mice ex vivo and that the quantification of this autoreactive T cell population in peripheral blood is a powerful predictor of autoimmune diabetes.This article was published online in advan...