GAD65-Specific CD4+ T-Cells with High Antigen Avidity Are Prevalent in Peripheral Blood of Patients With Type 1 Diabetes

Abstract

Negative selection of self-reactive T-cells during thymic development, along with activation-induced cell death in peripheral lymphocytes, is designed to limit the expansion and persistence of autoreactive T-cells. Autoreactive T-cells are nevertheless present, both in patients with type 1 diabetes and in at-risk subjects. By using MHC class II tetramers to probe the T-cell receptor (TcR) specificity and avidity of GAD65 reactive T-cell clones isolated from patients with type 1 diabetes, we identified high-avidity CD4؉ T-cells in peripheral blood, coexisting with low-avidity cells directed to the same GAD65 epitope specificity. A variety of cytokine patterns was observed, even among T-cells with high MHC-peptide avidity, and the clones utilize a biased set of TcR genes that favor two combinations, V␣12-␤5.1 and V␣17-V␤4. Presence of these high-avidity TcRs indicates a failure to delete autoreactive T-cells that likely arise from oligoclonal expansion in response to autoantigen exposure during the progression of type 1 diabetes.

Recurrence of autoreactive antigen-specific CD4+ T cells in autoimmune diabetes after pancreas transplantation

“…Tetramer staining was strong for all clones, and all five clones derived from subject #2 utilized the TCR Vβ 5.1 segment and had an identical CDR3 region, CASSFTGDTGELFF. Interestingly, preferential usage of TCR Vβ 5.1 has been seen in previous studies, associated with GAD-specific CD4+ T cell responses in a variety of HLA-DR4-positive T1D subjects [6]. Flow cytometry analysis of subsequent samples from this subject, in addition to tetramer staining, included Vβ 5.1 analysis.…”

“…MHC tetramers have been used to detect autoreactive antigen-specific CD4+ T cells in human subjects associated with T1D, MS, pemphigus vulgaris, and celiac disease [2,4,6,11,[16][17][18][19]. Because construction of appropriate MHC tetramers requires knowledge both of the HLA restriction element and of a suitable peptide epitope, diseases that have dominant HLA gene associations and dominant autoantigen targets are well suited for application of this technology, whereas other autoimmune disorders with more heterogeneous genetics or antigen targets are less optimal.…”

“…This T cell population is heterogeneous, with a range of antigen avidity and a diverse T cell receptor (TCR) utilization profile, albeit dominated by a high avidity Vb5.1 subpopulation in some subjects [6]. Cloning of these cells has revealed a pleomorphic cytokine profile, indicative of relatively uncommitted lineages of T cells, and the correlation of any specific T cell to a specific disease phenotype has been elusive.…”

IL-10 Gene Modified Dendritic Cells Inhibit T Helper Type 1-Mediated Alloimmune Responses and Promote Immunological Tolerance in Diabetes

“…In this disease, the islet β cells are impaired by pathogenic autoimmune CD4 + Th1 and CD8 + T recognizing islet β cell autoantigens, such as glutamic acid decarboxylase (GAD65), islet antigen-2 or islet cell antibody 512 (ICA512) and insulin related antigens (18). As the consequence, the insulin secretion decreases or suspends.…”

Inhibition of altered peptide ligand‐mediated antagonism of human GAD65‐responsive CD4+ T cells by non‐antagonizable T cells

“…hGAD65 (555-567)-responsive CD4 + T cell clones were obtained as previously described [31]. Briefly, PBMC were isolated from heparinized whole blood by gradient centrifugation using Lymphoprep (Nycomed, Oslo, Norway) and were in vitro stimulated with 10 lg/ml GAD65 (555-567) F557I.…”