INCREASED IN-VITRO AND IN-VIVO TUMORICIDAL ACTIVITY OF A MACROPHAGE CELL-LINE GENETICALLY-ENGINEERED TO EXPRESS IFN-GAMMA, IL-4, IL-6, OR TNF-ALPHA

Genetically engineered monocytes and macrophages may have potential as effector cells for the adoptive immunotherapy of cancer. As a first s tep, we have transfected the genes encoding either mouse interferon (I FN)-gamma, human interleukin (IL)-6, mouse IL-4, or mouse tumor necros is factor (TNF)-alpha into the mouse macrophage cell line, J774A.1 cel ls using retroviral vectors. In vitro activation of J774A.1 cells by g ene modification was assessed by morphological changes, proliferative activity was determined by [H-3]-TdR uptake, and cytolytic activity wa s assessed using an 18-hour chromium-51 (Cr-51) release assay. In vivo tumoricidal activity was studied by means of local adoptive immunothe rapy using intratumoral injection of transfected effector cells. IFN-g amma gene-transfected J774A.1 [J7(IFN-gamma)] cells developed filament ous processes, increased doubling times, and enhanced tumoricidal acti vity against three tumor cell lines: the TNF-sensitive fibrosarcoma li ne WEH I 164 and the TN F-alpha-resistant cell lines B16 melanoma and C1300 neuroblastoma. IL-6-, TNF-alpha-, and IL-4 gene-transfected J774 A.1 cells also had augmented tumoricidal activity but did not display any changes in morphology or growth. Cytolytic activity was markedly r educed after the addition of anti-TNF-alpha antibodies. Cytolytic J7(I FN-gamma) cells showed upregulated expression of TNF-alpha messenger R NA. After intratumoral injection of j7(IL-4) and J7(IFN-gamma) cell mi xtures, 50% of established B16 melanomas were rejected by C57BL/6 mice , thereby demonstrating synergistic killing. Further studies on gene-t ransfected macrophages should better define their potential usefulness in tumor immunotherapy.