Elicitation of a systemic and protective anti-melanoma immune response by an IL-2-based vaccine. Assessment of critical cellular and molecular parameters.

Abstract

We have established a model for the immunologic rejection of melanoma cells. Using a receptor-mediated, adenovirus-augmented gene delivery system (transferrinfection) we have shown that, upon transfection with an IL-2 gene construct, MHC class I+/class II- murine M-3 cells lose their tumorigenicity in both athymic and euthymic mice. More importantly, we found that these melanoma cells, which produce high levels of IL-2, can be used to induce a long-lasting anti-tumor immune response in syngeneic euthymic DBA/2 mice but not in athymic animals. This immune response, which can also be elicited by coadministration of nonmodified, irradiated M-3 cells and IL-2-transduced fibroblasts, results in the rejection of a subsequent challenge with M-3 cells or, in the elimination of preexisting M-3 cancer cell deposits. We found that transfer of T cell-enriched, but not of T cell-depleted, splenocytes from immunized mice conferred protection against M-3 cells, but not against unrelated KLN 205 cancer cells. Transfer of either CD4+ or CD8+ T cells led to only partial protection against challenge with wild-type M-3 cells. Our further observations that T cell-enriched, but not T cell-depleted splenocytes of immunized animals are capable of tumor-specific lytic activity and that this activity resides in the CD8+ cell population are compatible with the assumption that MHC class I-restricted T cell cytotoxicity is a biologically relevant effector mechanism in this model. That other mechanisms also contribute to melanoma cell destruction is evidenced by the presence of large numbers of macrophages and granulocytes in addition to T cells at the challenge sites of immunized mice.

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“…In several tumor models, it has been shown that systemic immunity is associated with the clonal selection of tumor-specific CD8 + or CD4 + T cells. Low concentration of mIFN␥ at the site of antigen presentation may not result in a significant enhancement of the cellular immune response, and therefore rejection of the tumor inoculum does not occur (7). In this study, specific CTL responses were observed in the spleens of mice immunized with irradiated tumor cells supplemented with a cytokine dose of mIFN␥-liposomes (300 ng mIFN␥) within the optimal dose range for antitumor protection (Fig.…”

“…The finding by Zatloukal cells and offer therefore an attractive alternative to cytokinegene transfection of tumor cells. Currently, studies are in prog-et al (7) that s.c. inoculation of 1 ϫ 10 5 IL-2-gene transfected M3 melanoma cells does not lead to detectable serum IL-2-ress to optimize the release characteristics of the liposomal cytokine formulation to improve their adjuvanticity in tumor-levels, whereas mice can be effectively protected against a tumor challenge after immunization with these transfected M3 cell based vaccines. cells, suggestes that the cytokine induces its immune potentiating effect locally at the vaccination site.…”

“…Outer Membrane of the Liposomes The plasmid DNA encoding for the IFN␥-gene was inserted into the tumor cells using an adenovirus enhanced Liposomes were incubated in the presence of the proteotransferrinfection (AVET) system as described previously lytic enzyme trypsin to determine the fraction of liposome- (4,7,15). The transfected cells were irradiated (50 Gy) to prevent bound mIFN␥ exposed on the outer surface of the liposomes.…”

Ancrer des cytokines aux cellules cancéreuses à l’aide de la toxine diphtérique : mieux que l’immunothérapie par transfert de gène ?

“…Cette approche est efficace, mais difficilement généralisable car elle implique le clonage d'un anticorps anti-tumoral et la construction d'une protéine hybride pour chaque type de tumeur. Une deuxième solution consiste à faire exprimer des cytokines directement par la tumeur (Abdel-Wahab et al, 1997 ;Arca et al, 1996 ;Chong et al, 1998 ;Fearon et al, 1990 ;Hoshino et al, 1998 ;Porgador et al, 1995 ;Schmidt et al, 1997 ;Schmidt et al, 1995 ;Zatloukal et al, 1995). Cette approche semble très promet teuse chez l'animal, et des essais cliniques sont en cours chez l'Homme (Palmer et al, 1999 ;Schmidt-Wolf et al, 1999 ;Schreiber et al, 1999 ;Stewart et al, 1999).…”

Preparation of Adenovirus‐Polylysine‐DNA Complexes

“…The high transfection efficiency of this sys-tem (typically 40% of primary mouse fibroblasts) has facilitated gene correction experiments using fibroblasts derived from geneknockout mice (Schreiber et al, 1995). This system has been used to activate immune responses in a tumor vaccine application (Zatloukal et al, 1994(Zatloukal et al, , 1995. Coupled plasmid copies of adenoviral genes have been used to transiently complement defective adenoviruses (Goldsmith et al, 1994;Scaria et al, 1995).…”