Ex vivo characterization of the MAGE T-cell response with the use of dextramers. (A-B) Ex vivo dextramer stain of patient PIN 5 (A) and PIN 15 (B) PBMCs counterstained with the MAGE-specific dextramer and anti-CCR7 and CD45RA Abs. (A) MAGE-A2_157-166–specific dextramer stain from PIN 5, 12 months after transplantation. (B) MAGE-A3_168-176–specific dextramer stain from PIN 15, 9 months after transplantation. (C) Expansion of the MAGE-A3_168-176–specific CD8⁺ T-cell response from PIN 15 showing expansion by ∼ 500-fold (from 0.01% to 5.6% of CD8 T cells). The percentage of dextramer-positive T cells is displayed on the x-axis and CD8 is displayed on the y-axis. The other 2 patients studied, PIN 5 and PIN 11, showed 20-fold (0.2% of CD8⁺ T cells) and 30-fold (0.3% of CD8⁺ T cells) expansions, respectively (data not shown).