Which feature is not shared between T cells & B cells?

Selection T cells Positive selection - T cells in thymic coex are allowed to survive only if TCR has affinity for MHC molecule. If not, they are programed to die Negative selection - T cell comes to thymic medulla after being positively selected in thymic coex. In the medulla, if they have affinity for self-antigens they are eliminated. Self-tolerance B cells Receptor editing/Negative selection - when B cells recognize self-antigens in bone marrow, BCR undergo gene rearrangement