Antitumor efficacy of a human interleukin-12 expression plasmid demonstrated in a human peripheral blood leukocyte/human lung tumor xenograft SCID mouse model.
Genes encoding the p35 and p40 subunits of human interleukin-12 (IL-12) and the bacterial aminoglycoside phosphotransferase were cloned into a mammalian expression plasmid. The resultant plasmid, pCMVIL-12neo, was used to transfect human lung tumor cell lines in vitro. Stably transfected subclones were generated and found to secrete human IL-12 for at least 10 days following a lethal dose of gamma-radiation. The ability of the IL-12--producing tumor cells to promote an antitumor response in vivo was evaluated in SCID mice co-engrafted subcutaneously with human peripheral blood lymphocytes (PBLs) and viable human lung tumor cells (SCID-Winn assay). Using this model system, it was established that IL-12 released locally into tumors by irradiated IL-12--transfected cells activated the human PBL and promoted their ability to suppress tumor development in a dose-dependent fashion. PBL subset depletion studies revealed that the antitumor effect promoted by the IL-12--modified cells was dependent on the presence of human CD8(+) T cells and, to a lesser extent, human CD56(+) natural killer cells within the xenograft. We conclude that (a) irradiated human lung tumor cells genetically modified with pCMVIL-12neo secrete bioactive human IL-12 at concentrations sufficient to promote a human lymphocyte-mediated antitumor response in the microenvironment of the xenograft, and (b) that the SCID-Winn assay provides a useful model for the preclinical evaluation of cytokine-based human immunotherapy protocols.
Hess
S D
SD
Department of Immunology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Egilmez
N K
NK
Shiroko
J
J
Bankert
R B
RB
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002294:Carcinoma, Squamous Cell / Q000276:immunology / Q000628:therapy*; D017690:Cell Transplantation; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation / Q000276:immunology; D005822:Genetic Vectors; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D018664:Interleukin-12 / Q000235:genetics* / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology; D007962:Leukocytes / Q000166:cytology / Q000276:immunology*; D008175:Lung Neoplasms / Q000276:immunology / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D010957:Plasmids; D014162:Transfection; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D018664:Interleukin-12