Autoreactivity of T cells selected by a single MHC/peptide ligand

Excerpt

T cell development in the thymus is characterised by positive and negative selection. These processes contribute to the development of a peripheral repertoire of T cells best suited to the recognition of foreign peptides in the context of self-major histocompatability complex (MHC) molecules. Recent work has focused on the contribution a single MHC/peptide complex makes to the selection of the mature repertoire. Mouse strains have been developed that express MHC class II molecules loaded with a single peptide species. The peripheral CD4⁺ T cell repertoire in these mice is diverse, although total numbers of CD4⁺ T cells are reduced by up to 80%, reflecting limited positive selection. Negative selection of CD4⁺ T cells recognising a wide array of self-peptides does not occur and so, as expected, the CD4⁺ T cells are able to recognise self-MHC molecules expressing self-peptides. Detailed analyses of the function of these cells has not previously been reported. To investigate the function of CD4⁺ T cells selected by a single ligand in the thymus. …