| Abstract: | Negative selection depletes self-reactive T cells, thus ensuring self-tolerance. It is usually considered that negative selection imposed on double-positive (DP) thymocytes that reside at the cortico-medullary junction. Negative selection model was set up by injecting mice with anti-T cell receptor (TCR) monoclonal antibody (mAb) intraperitoneally in this work. As shown in phenotypic analysis of thymocytes, negative selection destroys not only cortical-type DP thymocytes, but also medullary-type CD3+TCRαβ+CD4SP and CD3+TCRαβ+CD8SP thymocytes. Negative selection of medullary-type single positive (SP) are more susceptible to apoptosis, while with development of the cells, their resistance to apoptosis increases. Therefore, negative selection does not operate on functionally mature thymocytes at the late stage. This result is a supplement to the traditional theory of negative selection. Negative selection of medullary-type thymocytes is probably to further deplete self-reactive T cells, thus producing precise TCR repertoire and inducing self-tolerance. |
