Expanded T cells from pancreatic lymph nodes of type 1 diabetic subjects recognize an insulin epitope

In autoimmune type 1 diabetes, pathogenic T lymphocytes are associated with the specific destruction of insulin-producing beta-islet cells. Identification of the autoantigens involved in triggering this process is a central question. Here we examined T cells from pancreatic draining lymph nodes, the site of islet-cell-specific self-antigen presentation. We cloned single T cells in a non-biased manner from pancreatic draining lymph nodes of subjects with type 1 diabetes and from non-diabetic controls. A high degree of T-cell clonal expansion was observed in pancreatic lymph nodes from long-term diabetic patients but not from control subjects. The oligoclonally expanded T cells from diabetic subjects with DR4, a susceptibility allele for type 1 diabetes, recognized the insulin A 1-15 epitope restricted by DR4. These results identify insulin-reactive, clonally expanded T cells from the site of autoinflammatory drainage in long-term type 1 diabetics, indicating that insulin may indeed be the target antigen causing autoimmune diabetes.     

Functional profiling of the Saccharomyces cerevisiae genome

Determining the effect of gene deletion is a fundamental approach to understanding gene function. Conventional genetic screens exhibit biases, and genes contributing to a phenotype are often missed. We systematically constructed a nearly complete collection of gene-deletion mutants (96% of annotated open reading frames, or ORFs) of the yeast Saccharomyces cerevisiae. DNA sequences dubbed 'molecular bar codes' uniquely identify each strain, enabling their growth to be analysed in parallel and the fitness contribution of each gene to be quantitatively assessed by hybridization to high-density oligonucleotide arrays. We show that previously known and new genes are necessary for optimal growth under six well-studied conditions: high salt, sorbitol, galactose, pH 8, minimal medium and nystatin treatment. Less than 7% of genes that exhibit a significant increase in messenger RNA expression are also required for optimal growth in four of the tested conditions. Our results validate the yeast gene-deletion collection as a valuable resource for functional genomics.