These results indicated that addition of the WT1 helper peptide vaccine to the WT1 CTL peptide vaccine promoted the immune response against WT1-expressing tumors by the increased infiltration of WT1-specific CD4+ and CD8+ T cells into the tumor sites, especially by the strong infiltration of WT1-specific CD8+ T cells, resulting in the formation of microscopic necrotic lesions. Here, CD4 is linked to neoplasm.