scholarly journals gp100/pmel 17 Is a Murine Tumor Rejection Antigen: Induction of “Self”-reactive, Tumoricidal T Cells Using High-affinity, Altered Peptide Ligand

1998 ◽  
Vol 188 (2) ◽  
pp. 277-286 ◽  
Author(s):  
Willem W. Overwijk ◽  
Allan Tsung ◽  
Kari R. Irvine ◽  
Maria R. Parkhurst ◽  
Theresa J. Goletz ◽  
...  
Keyword(s):  
T Cells ◽  
Mhc Class I ◽  
Tissue Differentiation ◽  
Tumor Rejection ◽  
Class I ◽  
Peptide Ligand ◽  
Altered Peptide Ligand ◽  
Target Tissue ◽  
Differentiation Antigens ◽  
High Affinity

Many tumor-associated antigens are nonmutated, poorly immunogenic tissue differentiation antigens. Their weak immunogenicity may be due to “self”-tolerance. To induce autoreactive T cells, we studied immune responses to gp100/pmel 17, an antigen naturally expressed by both normal melanocytes and melanoma cells. Although a recombinant vaccinia virus (rVV) encoding the mouse homologue of gp100 was nonimmunogenic, immunization of normal C57BL/6 mice with the rVV encoding the human gp100 elicited a specific CD8+ T cell response. These lymphocytes were cross-reactive with mgp100 in vitro and treated established B16 melanoma upon adoptive transfer. To understand the mechanism of the greater immunogenicity of the human version of gp100, we characterized a 9-amino acid (AA) epitope, restricted by H-2Db, that was recognized by the T cells. The ability to induce specific T cells with human but not mouse gp100 resulted from differences within the major histocompatibility complex (MHC) class I–restricted epitope and not from differences elsewhere in the molecule, as was evidenced by experiments in which mice were immunized with rVV containing minigenes encoding these epitopes. Although the human (hgp10025–33) and mouse (mgp10025–33) epitopes were homologous, differences in the three NH2-terminal AAs resulted in a 2-log increase in the ability of the human peptide to stabilize “empty” Db on RMA-S cells and a 3-log increase in its ability to trigger interferon γ release by T cells. Thus, the fortuitous existence of a peptide homologue with significantly greater avidity for MHC class I resulted in the generation of self-reactive T cells. High-affinity, altered peptide ligands might be useful in the rational design of recombinant and synthetic vaccines that target tissue differentiation antigens expressed by tumors.

608 Immunodominant listeria epitopes compete with vaccine-directed cd8+ t-cell responses rescued by peptide-MHC stabilizing modifications

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A644-A644
Author(s):  
John Flickinger ◽  
Jagmohan Singh ◽  
Yanki Yarman ◽  
Robert Carlson ◽  
Scott Waldman ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
T Cell ◽  
Cell Line ◽  
Mhc Class I ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Class I ◽  
Peptide Ligand ◽  
Altered Peptide Ligand ◽  
Cell Responses

BackgroundThe Gram-positive bacterium Listeria monocytogenes (Lm) is a promising vector for cancer immunotherapy due to its ability to directly infect antigen-presenting cells, induce potent CD8+ T-cell immunity, and remodel immunosuppressive tumor microenvironments.1 Recent clinical trials have demonstrated safety and immunogenicity of Lm-based cancer vaccines in lung, cervical, pancreatic, and other cancers. In colorectal cancer, the transmembrane receptor guanylyl cyclase C (GUCY2C) is an emerging target for immunotherapy.2 Here, we examined the immunogenicity of a recombinant strain of Listeria monocytogenes secreting GUCY2C (Lm-GUCY2C). Surprisingly, Lm-GUCY2C vaccination induced robust Lm-specific CD8+ T-cell immunity but failed to prime GUCY2C-specific CD8+ T-cell responses. These studies explore the hypothesis that immunodominant Lm antigens suppress primary immunity to subdominant GUCY2C epitopes in Lm-GUCY2CMethodsLm-GUCY2C expresses the extracellular domain of mouse GUCY2C23-429 downstream of an ActA promoter integrated into the genome of the live, attenuated delta actA delta inlB Lm strain. Altered peptide ligands were designed based on NetMHCpan 4.0 peptide-MHC binding algorithms and similarly cloned into Lm. Peptide-MHC class I complex stability was quantified by FACS-based surface peptide-MHC dissociation on the TAP-deficient cell line, RMA-S H-2Kd.3In vivo efficacy studies employed IFNγ-ELISpot quantification of T-cell responses and tumor challenge studies with the CT26 colorectal cancer cell line. Adenovirus expressing GUCY2C was used as a positive control.2 4ResultsLm-GUCY2C vaccination of BALB/c mice generated Lm-specific CD8+ T-cell responses but an absence of GUCY2C-specific immunity. Peptide-MHC stability studies revealed poor stability of the dominant GUCY2C254-262 epitope complexed with H-2Kd compared to H-2Kd-restricted Lm epitopes derived from the LLO and p60 Lm antigens. Mutation of the GUCY2C254-262 peptide at critical anchoring residues for binding H-2Kd revealed that the altered peptide ligand with an F255Y mutation significantly improved the stability of the GUCY2C254-262-H-2Kd complex. Similarly, vaccination of mice with recombinant Lm-GUCY2C expressing the altered peptide ligand (Lm-GUCY2CF255Y) restored GUCY2C immunogenicity and antitumor immunity.ConclusionsImmunodominant Lm antigens may interfere with immune responses directed to the vaccine target antigen GUCY2C by competing with GUCY2C epitope for MHC class I binding and presentation. Moreover, use of a substituted GUCY2C -peptide ligand with enhanced peptide-MHC class I stability restored GUCY2C-specific immunity in the context of Lm-GUCY2C, an approach that can be translated to patients. Importantly, these studies also suggest that ongoing Lm-based vaccine development programs targeting a variety of antigens in other cancer types may be similarly limited by the immunodominance of Lm epitopes.AcknowledgementsThe authors thank Dr. Peter Lauer for providing the pPL2 integration vector used in cloning Lm-GUCY2C and Dr. Sean Murphy for providing the RMA-S H-2Kd cell line.Ethics ApprovalStudies were approved by the Thomas Jefferson University IACUC (Protocol # 01956).ReferencesFlickinger JC, Rodeck U, Snook AE. Listeria monocytogenes as a Vector for Cancer Immunotherapy: Current Understanding and Progress. Vaccines (Basel) 2018;6. doi:10.3390/vaccines6030048.Snook AE, Baybutt TR, Xiang B, Abraham TS, Flickinger JC, Hyslop T, et al. Split tolerance permits safe Ad5-GUCY2C-PADRE vaccine-induced T-cell responses in colon cancer patients. J Immunother Cancer 2019;7:104. doi:10.1186/s40425-019-0576-2.Müllbacher A, Lobigs M, Kos FJ, Langman R. Alloreactive cytotoxic T-cell function, peptide nonspecific. Scand J Immunol 1999;49:563–9.Flickinger J. JC, Singh J, Carlson R, Leong E, Baybutt T, Barton J, et al. Chimeric Ad5.F35 vector evades anti-adenovirus serotype 5 neutralization opposing GUCY2C-targeted antitumor immunity. J Immunother Cancer 2020.

scholarly journals Human MHC Class I-restricted high avidity CD4+T cells generated by co-transfer of TCR and CD8 mediate efficient tumor rejection in vivo

2013 ◽  
Vol 2 (1) ◽  
pp. e22590 ◽  
Author(s):  
Shao-An Xue ◽  
Liquan Gao ◽  
Maryam Ahmadi ◽  
Sara Ghorashian ◽  
Rafael D Barros ◽  
...  
Keyword(s):  
T Cells ◽  
Mhc Class I ◽  
Cd4 T Cells ◽  
Tumor Rejection ◽  
Class I ◽  
High Avidity

scholarly journals 225 Optimal-affinity MAGE-A1-specific T cell receptors (TCRs) generated using the humanized TCR-transgenic mouse platform HuTCR are superior to human donor-derived TCRs

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A239-A239
Author(s):  
Ioannis Gavvovidis ◽  
Matthias Leisegang ◽  
Vivian Scheuplein ◽  
Matthias Obenaus ◽  
Thomas Blankenstein ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Cells ◽  
Mhc Class I ◽  
Class I ◽  
Human Donor ◽  
High Affinity ◽  
Cancer Testis

BackgroundAs cancer-testis antigens are self-antigens, T cells expressing high-affinity TCRs against such antigens are eliminated via negative selection. Therefore, human-derived TCRs are typically of low affinity and exhibit reduced anti-tumor activity. Affinity maturation by mutagenesis is a common tool to increase affinity but may result in reduced specificity and off-target toxicity. Using our proprietary HuTCR mouse platform, which consists of mouse lines carrying the full human TCR-a/ß loci and human HLA alleles, we have isolated naturally optimized high-affinity TCRs specific for the cancer-testis antigen MAGE-A1 and compared them in vitro and in vivo to human-derived MAGE-A1-specific TCRs that are currently reported to be in clinical development.MethodsMAGE-A1-specific TCRs were isolated from HuTCR mice immunized with the MAGE-1 antigen using scRNAseq or were synthesized based on publicly available databases of human donor-derived MAGE-A1-specific TCRs. All TCRs were re-expressed in primary human T cells as verified using peptide-MHC-multimer staining. Functional activity of the TCRs was analyzed by coculture with T2 target cells loaded with titrated amounts of epitope and measuring cytokine concentration by ELISA. Reactivity of TCRs to endogenously processed MAGE-A1 protein was assessed by coculture with tumor cell lines with variable MAGE-A1 and/or MHC-class-I expression. Tumor rejection potential of TCRs was evaluated in vivo using a syngeneic mouse model (TNA2 mice) expressing MAGE-A1 and HLA-A*02 on syngeneic tumor cells.ResultsImmunization of HuTCR mice with the MAGE-A1 antigen resulted in robust CD8+ T cell responses and several TCR clonotypes were identified by scRNAseq, with the majority of clonotypes being specific to the MAGE-A1-derived peptide KVLEYVIKV and TCR functional avidities ranging from 0.3nM to 3nM. In sharp contrast, human-derived TCRs of the same epitope specificity exhibited lower functional avidity with EC50 from 3nM to 60nM. In addition, HuTCR-mouse-derived TCRs were more sensitive in recognition of tumor cells expressing low MAGE-A1 and/or MHC-class-I. Adoptive T-cell transfer to TNA2-mice with established tumors resulted in complete rejection without relapse of tumors only in mice treated with HuTCR-mouse-derived TCR but not with human-derived or control TCRs.ConclusionsThe HuTCR mouse platform allows for the generation of high-affinity MAGE-A1-specific human TCRs with increased anti-tumor efficacy as compared to human-derived TCRs against the same cancer antigen. The in vitro and in vivo comparative data presented herein highlight the HuTCR-derived MAGE-A1-specific TCR as the most favorable candidate for clinical translation and a clinical trial evaluating its safety and efficacy in a variety of solid malignancies will be initiated November 2021.Ethics ApprovalAll animal experiments were performed according to institutional and national guidelines, after approval by the responsible authority (Landesamt für Gesundheit und Soziales, Berlin). Blood collection from healthy human donors was done after prior informed consent and experiments were conducted in accordance with the ethical standards of Declaration of Helsinki.

MHC Sınıf I ve MHC Sınıf II Gen Düzenlenmesi

2020 ◽  
Vol 8 (3) ◽  
pp. 144-156
Author(s):  
Şule KARATAŞ ◽  
Fatma SAVRAN OĞUZ
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Gene Regulation ◽  
Mhc Class I ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Class I ◽  
Mhc Molecules ◽  
Class Ii Mhc ◽  
Regulation Mechanisms

Introduction: Peptides obtained by processing intracellular and extracellular antigens are presented to T cells to stimulate the immune response. This presentation is made by peptide receptors called major histocompatibility complex (MHC) molecules. The regulation mechanisms of MHC molecules, which have similar roles in the immune response, especially at the gene level, have significant differences according to their class. Objective: Class I and class II MHC molecules encoded by MHC genes on the short arm of the sixth chromosome are peptide receptors that stimulate T cell response. These peptides, which will enable the recognition of the antigen from which they originate, are loaded into MHC molecules and presented to T cells. Although the principles of loading and delivering peptides are similar for both molecules, the peptide sources and peptide loading mechanisms are different. In addition, class I molecules are expressed in all nucleated cells while class II molecules are expressed only in Antigen Presentation Cells (APC). These differences; It shows that MHC class I is not expressed by exactly the same transcriptional mechanisms as MHC class II. In our article, we aimed to compare the gene expressions of both classes and reveal their similarities and differences. Discussion and Conclusion: A better understanding of the transcriptional mechanisms of MHC molecules will reveal the role of these molecules in diseases more clearly. In our review, we discussed MHC gene regulation mechanisms with presence of existing informations, which is specific to the MHC class, for contribute to future research. Keywords: MHC class I, MHC class II, MHC gene regulation, promoter, SXY module, transcription

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