RESUMO
Prophylactic tumor vaccination against subsequent tumor challenge depends on effective cross-priming in vivo. Professional APCs process tumor antigens from whole tumor cells and present them to CD4(+) and CD8(+) T cells. Data suggest that dendritic cells process antigens more efficiently from necrotic cells than from apoptotic cells in vitro. We compared the effect of apoptosis vs. necrosis in vivo using different tumor models (CT26, RENCA, B16 and CT26-HA). Apoptosis was induced by gamma-irradiation prior to injection and verified in vivo. Apoptotic CT26-HA, CT26-wt or RENCA prevented tumor outgrowth in 100%, 75% and 100%, respectively, of mice for more than 30 days after challenge. In contrast, injection of necrotic tumor cells led to protection of no more than 0-30%. Prolonged tumor-free survival was also observed in mice after vaccination with irradiated B16 cells. In vivo protection experiments correlated very well with in vitro cytotoxicity assays. Immunohistochemical analysis of the vaccine site showed a strong CD4(+) and CD8(+) T-cell response after injection of apoptotic cells, which was accompanied by the presence of dendritic cells. In contrast, necrotic cell vaccines attracted a strong local macrophage response. Our data clearly demonstrate that only apoptotic tumor cell vaccines induce a potent antitumor immune response.
Assuntos
Apoptose , Vacinas Anticâncer/administração & dosagem , Carcinoma de Células Renais/imunologia , Neoplasias Renais/imunologia , Melanoma Experimental/imunologia , Necrose , Animais , Anexina A5/metabolismo , Antineoplásicos/farmacologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Carcinoma de Células Renais/metabolismo , Carcinoma de Células Renais/patologia , Células Dendríticas/imunologia , Feminino , Marcação In Situ das Extremidades Cortadas , Neoplasias Renais/metabolismo , Neoplasias Renais/patologia , Ativação Linfocitária/imunologia , Macrófagos/imunologia , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Fagocitose/imunologia , Receptores de Quimiocinas/biossíntese , Receptores de Quimiocinas/fisiologia , Linfócitos T Citotóxicos/imunologia , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/metabolismo , Células Tumorais Cultivadas/efeitos da radiaçãoRESUMO
Recombinant soluble MHC molecules are widely used for visualization, activation and inhibition of antigen-specific immune responses. Using a genetic approach, we have generated two novel peptide-beta2-microglobulin-MHC constructs. We have linked the MHC molecule with the peptide of interest, without limiting the recognition by the cognate TCR. This molecule can also be joined with the IgG heavy chain resulting in a dimeric MHC-Ig fusion protein. These molecules bind antigen-specific T cells with high specificity and sensitivity, therefore, providing a valuable tool for detection as well as enrichment of antigen-specific T cells.
