Description
Positive and negative selection processes in the thymus are critical steps for T cell maturation and self-tolerance. We show that decreased positive selection and excessive negative selection are attributable to T cell-specific nuclear receptor co-repressor 1 (NCoR1) deficiency. NCoR1 protects thymocytes from negative selection through the transcriptional repression of Bim expression. NCoR1 is also required for effective T cell response against microbial infection. Thus, NCoR1 sets the transcriptional threshold for coordinated positive selection and negative selection as well as optimal T cell immunity in periphery.