title: Augmentation of tumor immunity by 6-mercaptopurine (6-MP) and its analogs in the double grafted tumor system in mice.
abstract: We investigated the antitumor effect of 6-mercaptopurine (6-MP) and its analogs using the double grafted tumor technique. BALB/c mice were inoculated intradermally with MethA fibrosarcoma cells at the right inguinal region on day 0 (the primary tumor) and at the left on day 10 (the secondary tumor). Intraperitoneal or intra-lesional administration of 6-MP, 6-mercaptopurine riboside (6-MP-r) and 6-mercaptopurine riboside triacetate (6-MPRTA) from day 3 to 7 dose-dependently inhibited growth of the secondary tumor. Without the primary inoculation, 6-MP showed no effect on growth of the tumor inoculated on day 10, indicating that the antitumor effect of 6-MP could not be attributable to its direct antimetabolic or tumoricidal action only, and that the primary tumor inoculation is necessary for these compounds to inhibits growth of the challenging tumor. 6-MP did not inhibit the secondary MethA growth in the BALB/c (nu/nu) mouse. Both CD4+ and CD8+ T cells increased in the spleen of mice treated with 6-MP. Meanwhile, delayed-type hypersensitivity (DTH) reaction to the methylated bovine serum albumin (MBSA) antigen at the footpad was not augmented but inhibited by 6-MP-r and 6-MPRTA in both normal and tumor-bearing mice. Thus, the immunomodulatory activity of 6-MP could be observed in two opposite directions, augmentation of tumor immunity and inhibition of DTH to MBSA. This indicates that the immune mechanism and/or the type of effector cells induced in these two cell-mediated immune systems are different from each other.
authors.affiliation: Research Laboratories, Tanabe Seiyaku Co., Ltd., Saitama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kashida
authors.forename: N
authors.initials: N
authors.lastname: Narasaki
authors.forename: A
authors.initials: A
authors.lastname: Sakai
authors.forename: K
authors.initials: K
authors.lastname: Tsujihara
authors.forename: K
authors.initials: K
authors.lastname: Tsuzurahara
authors.forename: S
authors.initials: S
authors.lastname: Takeyama
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D005354:Fibrosarcoma / Q000188:drug therapy / Q000276:immunology*; D006968:Hypersensitivity, Delayed; D007111:Immunity, Cellular / Q000187:drug effects; D007274:Injections, Intraperitoneal; D008297:Male; D015122:Mercaptopurine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000964:Antimetabolites, Antineoplastic; D015122:Mercaptopurine