1. Uptake routes of tumor-antigen MAGE-A3 by dendritic cells determine priming of naïve T-cell subtypes.
- Author
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Moeller I, Spagnoli GC, Finke J, Veelken H, and Houet L
- Subjects
- Antigen-Antibody Complex immunology, Antigens, Neoplasm metabolism, Antineoplastic Agents pharmacology, Apoptosis drug effects, Apoptosis immunology, Apoptosis radiation effects, Boronic Acids pharmacology, Bortezomib, CD4-Positive T-Lymphocytes drug effects, CD4-Positive T-Lymphocytes radiation effects, CD8-Positive T-Lymphocytes drug effects, CD8-Positive T-Lymphocytes radiation effects, Cell Line, Tumor, Dendritic Cells drug effects, Dendritic Cells radiation effects, Gamma Rays therapeutic use, Humans, Melanoma drug therapy, Melanoma immunology, Melanoma radiotherapy, Multiple Myeloma drug therapy, Multiple Myeloma immunology, Multiple Myeloma radiotherapy, Neoplasm Proteins metabolism, Pinocytosis immunology, Pyrazines pharmacology, Skin Neoplasms drug therapy, Skin Neoplasms immunology, Skin Neoplasms radiotherapy, Treatment Outcome, Antigens, Neoplasm immunology, CD4-Positive T-Lymphocytes immunology, CD8-Positive T-Lymphocytes immunology, Dendritic Cells immunology, Neoplasm Proteins immunology
- Abstract
Induction of tumor-antigen-specific T cells in active cancer immunotherapy is generally difficult due to the very low anti-tumoral precursor cytotoxic T cells. By improving tumor-antigen uptake and presentation by dendritic cells (DCs), this problem can be overcome. Focusing on MAGE-A3 protein, frequently expressed in many types of tumors, we analyzed different DC-uptake routes after additional coating the recombinant MAGE-A3 protein with either a specific monoclonal antibody or an immune complex formulation. Opsonization of the protein with antibody resulted in increased DC-uptake compared to the uncoated rhMAGE-A3 protein. This was partly due to Fcγ receptor-dependent internalization. However, unspecific antigen internalization via macropinocytosis also played a role. When analyzing DC-uptake of MAGE-A3 antigen expressed in multiple myeloma cell line U266, pretreatment with proteasome inhibitor bortezomib resulted in increased apoptosis compared to γ-irradiation. Bortezomib-mediated immunogenic apoptosis, characterized by elevated surface expression of hsp90, triggered higher phagocytosis of U266 cells by DCs involving specific DC-derived receptors. We further investigated the impact of antigen delivery on T-cell priming. Induction of CD8(+) T-cell response was favored by stimulating naïve T cells with either antibody-opsonized MAGE-A3 protein or with the bortezomib-pretreated U266 cells, indicating that receptor-mediated uptake favors cross-presentation of antigens. In contrast, CD4(+) T cells were preferentially induced after stimulation with the uncoated protein or protein in the immune complex, both antigen formulations were preferentially internalized by DCs via macropinocytosis. In summary, receptor-mediated DC-uptake mechanisms favored the induction of CD8(+) T cells, relevant for clinical anti-tumor response.
- Published
- 2012
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