Description
Mouse thymocytes can be classified into four major subsets based on expression of CD4 and CD8 co-receptors. CD4-CD8- (double negative, DN) cells become CD4+CD8+ (double positive, DP) cells following productive T cell receptor (TCR) beta chain rearrangement. A small proportion of DP cells are selected through interaction of clonal TCRalpha/beta and MHC self peptide complex expressed on thymic stromal cells. DP cell expressing MHC class I-restricted TCR become CD4-CD8+ cells, which will finally differentiate into cytotoxic T cells, while MHC class II restricted selection generates CD4+CD8- helper lineage T cells.