Lymphocytes genetically modified to express tumor antigens target DCs in vivo and induce antitumor immunity
Vincenzo Russo, Arcadi Cipponi, Laura Raccosta, Cristina Rainelli, Raffaella Fontana, Daniela Maggioni, Francesca Lunghi, Sylvain Mukenge, Fabio Ciceri, Marco Bregni, Claudio Bordignon, Catia Traversari
Vincenzo Russo, Arcadi Cipponi, Laura Raccosta, Cristina Rainelli, Raffaella Fontana, Daniela Maggioni, Francesca Lunghi, Sylvain Mukenge, Fabio Ciceri, Marco Bregni, Claudio Bordignon, Catia Traversari
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Research Article Oncology

Lymphocytes genetically modified to express tumor antigens target DCs in vivo and induce antitumor immunity

Abstract

The exploitation of the physiologic processing and presenting machinery of DCs by in vivo loading of tumor-associated antigens may improve the immunogenic potential and clinical efficacy of DC-based cancer vaccines. Here we show that lymphocytes genetically modified to express self/tumor antigens, acting as antigen carriers, efficiently target DCs in vivo in tumor-bearing mice. The infusion of tyrosinase-related protein 2–transduced (TRP-2–transduced) lymphocytes induced the establishment of protective immunity and long-term memory in tumor-bearing mice. Analysis of the mechanism responsible for the induction of such an immune response allowed us to demonstrate that cross-presentation of the antigen mediated by the CD11c+CD8α+ DC subset had occurred. Furthermore, we demonstrated in vivo and in vitro that DCs had undergone activation upon phagocytosis of genetically modified lymphocytes, a process mediated by a cell-to-cell contact mechanism independent of CD40 triggering. Targeting and activation of secondary lymphoid organ–resident DCs endowed antigen-specific T cells with full effector functions, which ultimately increased tumor growth control and animal survival in a therapeutic tumor setting. We conclude that the use of transduced lymphocytes represents an efficient method for the in vivo loading of tumor-associated antigens on DCs.

Authors

Vincenzo Russo, Arcadi Cipponi, Laura Raccosta, Cristina Rainelli, Raffaella Fontana, Daniela Maggioni, Francesca Lunghi, Sylvain Mukenge, Fabio Ciceri, Marco Bregni, Claudio Bordignon, Catia Traversari

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Figure 1

Infusion of TRP-2–GMLs protects mice from tumor challenge, induces memory responses, and prolongs survival of tumor-bearing mice.

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Infusion of TRP-2–GMLs protects mice from tumor challenge, induces memor...
(A) B6 splenocytes were transduced with the retroviral vector TRP-2–CSM encoding TRP-2 and the ΔLNGFr marker. (B) Transduction efficiency. Ninety percent of CD3+ cells (middle and right panels) expressed ΔLNGFr (right panel). Mock-transduced splenocytes were negative (middle panel). (C) B6 mice were treated with mock-transduced GMLs; TRP-2–GMLs from WT (TRP-2 WT) or β2m–/– mice (TRP-2 β2m–/–); or DCs pulsed with 2 TRP-2 peptides (TRP-2–pulsed DCs). TRP-2–GMLs from both WT and β2m–/– mice were able to control tumor growth. *P = 0.03, **P < 0.05; Student’s t test. (D) The infusion of TRP-2–GMLs elicits TRP-2–specific cytotoxic T cells. Splenocytes from vaccinated mice were restimulated in vitro with TRP-2 peptides and tested in a cytotoxicity assay against pulsed (filled symbols) or unpulsed (open symbols) RMA cells. (E) Induction of memory antitumor responses. Forty days after vaccination, B16 cells were implanted s.c. TRP-2–GMLs from both WT and β2m–/– mice were able to control tumor growth. †P < 0.005,‡P < 0.0005; Student’s t test. Data shown in C and E are representative of 2 experiments with 5 mice/group. (F) Kaplan-Meier survival graphs. Mice were treated as described in Methods. Statistical comparison of the survival curves, performed by the log-rank test, gave the following results: 4 × 106 TRP-2–GMLs versus mock-GMLs, P < 0.005; 10 × 106 TRP-2–GMLs versus mock-GMLs, P < 0.005; TRP-2–pulsed DCs versus mock-GMLs, P < 0.005.