WT1 and neoplasm: Next, to examine the infiltration of WT1-specific helper CD4+ T cells into the tumors, tumor-infiltrated T cells (tumor cell suspension) were stimulated with WT1-specific helper peptide (WT135-52), which was used for the immunization of the mice, and WT1-specific helper peptide-specific TNF-α and/or IFN-γ production were analyzed by flow cytometry in CD3+ CD4+ T cells.