T Cell-Mediated, IFN-γ-Facilitated Rejection of Murine B16 Melanomas

Abstract

The murine melanoma cell line B16.F10 (H-2b) was used to study specific T cell responses that reject tumors. Stable B16 transfectants were established that express viral Ags, either the hepatitis B surface Ag (HBsAg) or the large tumor Ag (T-Ag) of SV40. B16 cells and their transfected sublines were CD40+CD44+ but expressed no (or low levels of the) costimulator molecules CD154 (CD40L), CD48, CD54, CD80, and CD86. Surface expression of MHC class I (Kb, Db) and class II (I-Ab) molecules by B16 cells was low, but strikingly up-regulated by IFN-γ. CD95 (Fas) and CD95 ligand (CD95L (FasL)) were “spontaneously” expressed by B16 cells growing in vitro in serum-free medium; these markers were strikingly up-regulated by IFN-γ. B16 cells coexpressing CD95 and CD95L were irreversibly programed for apoptosis. In vitro, noninduced B16 transfectants stimulated a specific IFN-γ release response, but no cytolytic response (in a 4-h assay) in MHC class I-restricted CTL; in contrast, IFN-γ-induced B16 targets were efficiently and specifically lysed by CTL. In vivo, B16 transfectants were specifically rejected by DNA-vaccinated syngeneic hosts through a T-dependent immune effector mechanism. The tumors showed evidence of massive apoptosis in vivo during the rejection process. The data suggest that CTL-derived IFN-γ enhances an intrinsic suicide mechanism of these tumor cells in addition to facilitating lytic interactions of effectors with tumor targets.

Mouse Model for Pre‐Clinical Study of Human Cancer Immunotherapy

“…Both human melanomas and B16 can often be induced to express MHC Class II by IFN-γ treatment. (Bohm et al, 1998;Surman et al, 2000) Humans can survive for months or years despite melanoma growth; a minimal tumorigenic dose of B16 melanoma (intravenous or subcutaneous) will kill an untreated mouse within weeks.…”

Endogenous viral elements constitute a complementary source of antigens for personalized cancer vaccines

“…For B16F10, two immunopeptidomics datasets were generated using IFNy-stimulated cells and in vivo grown tumors. Unstimulated B16F10 cells were not analyzed as previous studies have reported poor MHC presentation on unstimulated B16F10 cells 23 . A total of 7078 unique sequences without PTMs were identified across the two datasets (Figure S1G).…”

OncoVEXmGM-CSFexpands tumor antigen-specific CD8+ T-cell response in preclinical models

“…The B16F10 murine syngeneic tumor cells have low levels of MHC-I antigen presentation at cell surface 30 and are infiltrated with low numbers of T cells when grown as subcutaneous tumors in vivo, 31 representing the immunologically cold tumor phenotype observed in human cancers that tend to be refractory checkpoint inhibitor treatment. B16F10 has been widely reported to be resistant to checkpoint inhibitors, including anti-CTLA-4, anti-PD-1, and anti-PD-L1 mAbs when given as monotherapy treatments.…”