NY-ESO-1–specific CD4⁺ T cells are present in an ATLL patient (patient 19) receiving an allogeneic hematopoietic stem cell transplantation. CD4⁺ T cells were presensitized by CD4⁻ CD8⁻ PBMCs pulsed with NY-ESO-1 peptide covering the entire sequence of NY-ESO-1 as described in “In vitro sensitization.” Induction of NY-ESO-1–specific CD4⁺ T cells was analyzed by intracellular cytokine staining using autologous activated T-cell APCs pulsed with NY-ESO-1 peptides. These experiments were performed independently twice with similar results.