Antigen/MHC-specific T cells are preferentially exported from the thymus in the presence of their MHC ligand |
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Authors: | L J Berg A M Pullen B Fazekas de St Groth D Mathis C Benoist M M Davis |
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Institution: | Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305. |
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Abstract: | 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". |
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