Histological analysis of the biopsy sample. Hematoxylin and eosin (H & E) staining (a-a”, f-f”) and immunohistochemistry of serial sections of tissues for Wilms tumor 1 (WT1) (b-b”, g-g”) and mucin 1, cell-surface associated (MUC1) (c-c”, h-h”). (a-a”, f-f”) H & E staining before and after vaccination. H & E staining showing signet-ring cells in tissue before vaccination (a-a”). One month after the final administration, pathological examination revealing normal luminal epithelial cells (f-f”). (b-b”, g-g”) Staining for WT1 before and after vaccination. Samples positive for WT1 in approximately 60% of the cells before vaccination at the tumor site (b-b”) and the remarkable reduction in WT1 positivity confirmed after vaccination (g-g”). (c-c”, h-h”) Staining for MUC1 before and after vaccination. Approximately 70% of tumor cells were positive for MUC1 before vaccination (c-c”) and MUC1 staining was observed in normal glands only after vaccination (f-f”). Immunohistochemical staining of CD4+ and CD8+ T-cells in the biopsy samples. Serial sections of the tissues used for H & E staining prepared and stained for CD4 and CD8 (d, e, i, j). (d-d”, i-i”) Staining for CD4 before (d-d”) and after vaccination (i-i”). (e-e”, j-j”) Staining for CD8 before (e-e”) and after vaccination (j-j”). CD4+ and CD8+ T-cells observed more frequently in normal gastric tissues after vaccination than had been observed in tumor tissues before vaccination. (Magnification: a-j 4×, a’-j’ 10×, a”-j” 20×).