PROBLEM TO BE SOLVED: To activate a helper T cell.SOLUTION: A method for activating a helper T cell includes a process of adding a WT1 peptide to an antigen-presenting cell and activating a helper T cell. The WT1 peptide has capability of bonding to any MHC class II molecule out of an HLA-DRB10101 molecule, an HLA-DRB10401 molecule, an HLA-DRB10403 molecule, an HLA-DRB10406 molecule, an HLA-DRB10803 molecule, an HLA-DRB10901 molecule, an HLA-DRB11101 molecule, an HLA-DRB30202 molecule, an HLA-DRB40101 molecule, an HLA-DPB10201 molecule and an HLA-DPB10301 molecule.SELECTED DRAWING: None【課題】ヘルパーT細胞を活性化させること。【解決手段】WT1ペプチドを抗原提示細胞に添加して、ヘルパーT細胞を活性化させる工程を含む、ヘルパーT細胞の活性化方法であって、該WT1ペプチドが、HLA-DRB1*0101分子、HLA-DRB1*0401分子、HLA-DRB1*0403分子、HLA-DRB1*0406分子、HLA-DRB1*0803分子、HLA-DRB1*0901分子、HLA-DRB1*1101分子、HLA-DRB3*0202分子、HLA-DRB4*0101分子、HLA-DPB1*0201分子またはHLA-DPB1*0301分子のうちのいずれかのMHCクラスII分子に結合する能力を有するものである方法。【選択図】なし