Induction of cytotoxic T cells and their antitumor activity in mice transgenic for carcinoembryonic antigen

Abstract

In order to develop immunotherapy strategies that are based on eliciting immune responsiveness to the self-antigen, human carcinoembryonic antigen (CEA), we examined whether cytotoxic T lymphocyte (CTL) activity against CEA could be elicited in CEA-transgenic and nontransgenic mice. CEA-transgenic [C57BL/ 6-TGN(CEAGe)18FJP] and nontransgenic mice were primed with CEA-transfected syngeneic fibroblasts in combination with Corynebacterium parvum. Spleen cells from immunized mice were cultured with irradiated syngeneic MC-38 colon carcinoma cells transfected with CEA (MC-38.CEA) as stimulators prior to the measurement of CTL activity. Primed nontransgenic spleen cells showed augmented CTL activity against MC-38.CEA cells as compared with control parental MC-38 cells, nontransfected or transfected with vector only. Moreover, primed CEA transgenic spleen cells showed augmented CTL activity against MC-38.CEA cells that was similar to that observed in nontransgenic mice. All CTL clones derived from either transgenic or nontransgenic mice showed cross-reactivity with MC-38 cells expressing the CEA-related antigen, nonspecific cross-reacting antigen, but not biliary glycoprotein. CEA-specific CTL clones were not identified. Adoptive transfer of cloned CTL resulted in inhibition of MC-38.CEA but not MC-38.BGP tumor growth. Tumor cures were elicited in mice treated with a combination of cloned CTL and cyclophosphamide. Histopathological examination of CEA-expressing colons from either immunized mice or recipients of cloned CTL did not reveal any autoimmune reactions. These studies demonstrate that CTL recognizing cross-reactive class I epitopes on the CEA molecule can be induced in transgenic mice. The expression of these epitopes on tumor cells creates effective targets for CTL in vivo without inducing adverse reactions in CEA-expressing normal tissues. Since anti-CEA CTL have been generated in humans, CEA-transgenic mice may be a useful model to study vaccines that are based on CTL effector mechanisms.

Efficient induction of T‐cell responses to carcinoembryonic antigen by a heterologous prime‐boost regimen using DNA and adenovirus vectors carrying a codon usage optimized cDNA

“…52 The latter strain is commonly used as the mouse model of choice in determining the efficacy of a variety of immunotherapy approaches that target CEA. 53,54 In our study, Tcell responses to pools of CEA peptides were induced in C57Bl/6 mice after DNA EP prime Ad boost regimen. The data reported confirm the immune response elicited by this antigen was primarily directed toward the C-terminal region in C57Bl/6 mice as observed upon immunization with a baculovirus vector carrying the CEAopt cDNA.…”

Inhibition of Tumor Growth with Antiangiogenic Cancer Vaccine Using Epitope Peptides Derived from Human Vascular Endothelial Growth Factor Receptor 1

“…The immunized mice were sacrificed on day 21 and the spleens were harvested. The lymphoid cells were prepared from the spleens and stimulated in vitro using antigenpresenting cells prepared as follows with the method described previously (45). The spleen cells from each mouse were stimulated separately with peptide-pulsed B-cell blasts at a 3:1 responder/feeder ratio.…”

Single-Domain Antibody–Based and Linker-Free Bispecific Antibodies Targeting FcγRIII Induce Potent Antitumor Activity without Recruiting Regulatory T Cells

“…31, 32) were cultured in Dulbecco's Modified Eagle Medium (DMEM) þ GlutaMax-I medium (Invitrogen) supplemented with 10% FBS (PAA). MC38 and C15.4.3.AP (MC38-CEA) cells are murine colorectal cancer cells (33). MC38-CEA cells are MC38 cells transfected with a cDNA encoding CEA.…”