CD8A and listeriosis: Although we do not formally show that the defective CD8+ T cell response of A20-deficient CD8+ T cells is only caused by the intrinsic A20-defect, these in vivo data in combination with the corresponding in vitro phenotype of A20-deficient CD8+ T cells strongly suggest that A20 expression in CD8+ T cells is the major factor causing the altered CD8+ T cell response in listeriosis.