Related Experiment Videos
Deletion of the CD4 silencer element supports a stochastic mechanism of thymocyte lineage commitment
R K Leung1, K Thomson, A Gallimore
1Nuffield Department of Clinical Medicine, University of Oxford, Level 7, John Radcliffe Hospital, Oxford OX3 9DU, UK.
Abstract:
The mechanism of T cell lineage commitment remains controversial; to examine it we deleted the CD4-silencer element in the germ line of a mouse using a combination of gene targeting and Cre/LoxP-mediated recombination. We found that these mice were unable to extinguish CD4 expression either in immature thymocytes or mature CD8+ cytotoxic T cells (CTLs), which resulted in the development of major histocompatibility complex class II-restricted double-positive CTLs in the periphery. This finding strongly supports a stochastic over an instructive mechanism of coreceptor down-regulation.