Induction of tumor cell apoptosis in vivo increases tumor antigen cross-presentation, cross-priming rather than cross-tolerizing host tumor-specific CD8 T cells

AK Nowak, RA Lake, AL Marzo, B Scott… - The Journal of …, 2003 - journals.aai.org
AK Nowak, RA Lake, AL Marzo, B Scott, WR Heath, EJ Collins, JA Frelinger, BWS Robinson
The Journal of Immunology, 2003journals.aai.org
Cross-presentation of cell-bound Ags from established, solid tumors to CD8 cells is efficient
and likely to have a role in determining host response to tumor. A number of investigators
have predicted that when tumor Ags are derived from apoptotic cells either no response, due
to Ag “sequestration,” or CD8 cross-tolerance would ensue. Because the crucial issue of
whether this happens in vivo has never been addressed, we induced apoptosis of
established hemagglutinin (HA)-transfected AB1 tumors in BALB/c mice using the apoptosis …
Abstract
Cross-presentation of cell-bound Ags from established, solid tumors to CD8 cells is efficient and likely to have a role in determining host response to tumor. A number of investigators have predicted that when tumor Ags are derived from apoptotic cells either no response, due to Ag “sequestration,” or CD8 cross-tolerance would ensue. Because the crucial issue of whether this happens in vivo has never been addressed, we induced apoptosis of established hemagglutinin (HA)-transfected AB1 tumors in BALB/c mice using the apoptosis-inducing reagent gemcitabine. This shrank the tumor by∼ 80%. This induction of apoptosis increased cross-presentation of HA to CD8 cells yet neither gross deletion nor functional tolerance of HA-specific CD8 cells were observed, based on tetramer analysis, proliferation of specific CD8 T cells, and in vivo CTL activity. Interestingly, apoptosis primed the host for a strong antitumor response to a second, virus-generated HA-specific signal in that administration of an HA-expressing virus after gemcitabine administration markedly decreased tumor growth compared with viral administration without gemcitabine. Thus tumor cell apoptosis in vivo neither sequesters tumor Ags nor cross-tolerizes tumor-specific CD8 cells. This observation has fundamental consequences for the development of tumor immunotherapy protocols and for understanding T cell reactivity to tumors and the in vivo immune responses to apoptotic cells.
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