Reconstitution of A2/Melan-A⁺ CD8⁺ T cells after UCBT. The frequency of A2/Melan-A⁺ CD8⁺ T cells was measured ex vivo (A) and after PHA stimulation (B) in UCB graft inoculums and UCBT recipients. Statistical significance was tested with the Mann-Whitney U test. Boxes represent median and interquartile range; error bars represent the range; and n represents the number of subjects.