Peripheral WT1-specific T cells differentiate into memory T cells without vaccination. (A) CD44 and CD62L expression on gated TCR-expressing (TCR⁺) and gated TCR⁻ peripheral T cells as determined by FACS analysis after staining with anti–murine CD44 and CD62L antibodies. Similar staining patterns were observed for both splenocytes and LN (shown here). (Top and middle panels) Resentative plots from A2Kb Tg mice transplanted with A2Kb stem cells transduced with the WT1-TCR (top panel, n = 8) or the LMP2-TCR (middle panel, n = 5). (Bottom panel) Representative plots from A2Kb Tg mice transplanted with B6-derived stem cells transduced with the WT1-TCR (n = 8). (B) Summary data of naive (CD44^low, CD62L^high), CM (CD44^high, CD62L^high), and EM (CD44^high, CD62L^low) T-cell frequencies in transplanted mice expressing WT1-TCR or LMP2-TCR. ***P < .001. **P < .01. A2Kb → A2Kb or B6 → A2Kb as indicated in the figure. (C) Phenotypic analysis of gated WT1-TCR^hi and WT1-TCR^lo peripheral T-cell populations in A2Kb recipients after transplantation with TCR-Td B6 stem cells, after staining with anti–murine CD44, CD62L, and CD8 antibodies. ns indicates not significant.