title: Multiple roles of interferon-gamma in the mediation of interleukin 12-induced tumor regression.
abstract: Administration of recombinant interleukin 12 (IL-12) induces tumor regression that is associated with T-cell infiltration in the OV-HM ovarian carcinoma and CSA1M fibrosarcoma models. After confirming the blocking of regression by injection of anti-IFN-gamma monoclonal antibody (mAb), we investigated the mechanisms underlying the requirement of IFN-gamma in T-cell migration and tumor regression. T-cell migration was inhibited by injection of anti-IFN-gamma mAb to OV-HM tumor-bearing mice prior to IL-12 treatment. We examined, using the lymphoid cell migration assay, whether IFN-gamma is required for enhancing the migratory capacity of T cells or the T cell-accepting potential of tumor masses during IL-12 treatment. Spleen cells from IL-12-treated or untreated OV-HM-bearing mice were stained in vitro with a fluorescein chemical and transferred i.v. into OV-HM-bearing mice that were not treated with IL-12. Migration of donor cells was quantitated by counting the number of fluorescent cells on cryostat sections of tumor masses from recipient mice. Compared to spleen cells from OV-HM-bearing mice that were not treated with IL-12, enhanced migration was observed for cells from IL-12-treated OV-HM-bearing mice. Anti-IFN-gamma pretreatment of donor mice before IL-12 treatment did not reduce the migratory capacity of T cells, whereas migration was markedly inhibited in recipient mice injected with anti-IFN-gamma. Anti-IFN-gamma pretreatment decreased vascular cell adhesion molecule-1 (VCAM-1)-/intercellular adhesion molecule-1 (ICAM-1)-positive blood vessels at tumor sites. Consistent with this, migration was also inhibited by treatment of recipient mice with either anti-VCAM-1 or anti-ICAM-1 mAb. In contrast to the OV-HM model, T-cell migration was not affected in the CSA1M model following preinjection of anti-IFN-gamma mAb. In this model, VCAM-1-/ICAM-1-positive blood vessels existed even after anti-IFN-gamma treatment, although tumor regression was completely inhibited. These results indicate that IFN-gamma plays two distinct roles in expressing the antitumor efficacy of IL-12: one is to support the T-cell acceptability of tumor masses, and the other is to mediate the antitumor effects of migrated T cells.
authors.affiliation: Biomedical Research Center, Osaka University Medical School, Suita, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Ogawa
authors.forename: W G
authors.initials: WG
authors.lastname: Yu
authors.forename: K
authors.initials: K
authors.lastname: Umehara
authors.forename: M
authors.initials: M
authors.lastname: Iwasaki
authors.forename: R
authors.initials: R
authors.lastname: Wijesuriya
authors.forename: T
authors.initials: T
authors.lastname: Tsujimura
authors.forename: T
authors.initials: T
authors.lastname: Kubo
authors.forename: H
authors.initials: H
authors.lastname: Fujiwara
authors.forename: T
authors.initials: T
authors.lastname: Hamaoka
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002465:Cell Movement / Q000187:drug effects; D015536:Down-Regulation; D005260:Female; D005354:Fibrosarcoma / Q000098:blood supply / Q000188:drug therapy / Q000473:pathology; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis; D007371:Interferon-gamma / Q000502:physiology*; D018664:Interleukin-12 / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009374:Neoplasms, Experimental / Q000098:blood supply / Q000188:drug therapy* / Q000473:pathology; D009389:Neovascularization, Pathologic; D010051:Ovarian Neoplasms / Q000098:blood supply / Q000188:drug therapy / Q000473:pathology; D051381:Rats; D012074:Remission Induction; D013601:T-Lymphocytes / Q000187:drug effects; D014407:Tumor Cells, Cultured; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D018664:Interleukin-12; D007371:Interferon-gamma