Antigen/MHC-specific T cells are preferentially exported from the thymus in the presence of their MHC ligand.
Transgenic mice expressing a T cell receptor heterodimer specific for a fragment of pigeon cytochrome c plus an MHC class II molecule (I-Ek) have been made. We find that H-2k alpha beta transgenic mice have an overall increase in the number of T cells and express a 10-fold higher fraction of cytochrome c-reactive cells than H-2b mice. Surface staining of thymocytes indicates that in H-2b mice, T cell development is arrested at an intermediate stage of differentiation (CD4+8+, CD310). Analyses of mice carrying these T cell receptor genes and MHC class II I-E alpha constructs indicate that his developmental block can be reversed in H-2b mice by I-E expression on cortical epithelial cells of the thymus. These data suggest that a direct T cell receptor-MHC interaction occurs in the thymus in the absence of nominal antigen and results in the enhanced export of T cells, consistent with the concept of "positive selection".
Pubmed ID: 2476238 RIS Download
Animals | Antigens, CD5 | Antigens, CD8 | Antigens, Differentiation | Antigens, Differentiation, T-Lymphocyte | Flow Cytometry | Ligands | Major Histocompatibility Complex | Mice | Mice, Transgenic | Receptors, Antigen, T-Cell | T-Lymphocytes | Thymus Gland