T Cell Reactivity to MHC Molecules: Immunity Versus Tolerance
Abstract
The specificity of mature CD8^+ and CD4^+ T lymphocytes is controlled by major histocompatibility complex (MHC) class I and class II molecules, respectively. The MHC class specificity of T cells is stringent in many assays, but is less evident when cells are supplemented with exogenous lymphokines. The repertoire of T cells is shaped through contact with MHC molecules in the thymus and involves a complex process of positive selection and negative selection (tolerance). Tolerance of immature T cells to MHC molecules can reflect either clonal deletion or anergy and results from intrathymic contact with several cell types, including epithelial cells and cells with antigen-presenting function. Unlike immature T cells, mature T cells are relatively resistant to tolerance induction. In certain situations partial unresponsiveness of mature T cells can be achieved by exposing T cells to foreign MHC molecules expressed on atypical antigenpresenting cells. Tolerance is rarely complete, however, and the precise requirements for tolerizing mature T cells are still unclear.
- Publication:
-
Science
- Pub Date:
- June 1990
- DOI:
- 10.1126/science.1694041
- Bibcode:
- 1990Sci...248.1357S