Functional T-cell epitope discovery is a key process for the development of novel immunotherapies, particularly for cancer immunology. In vivo assays of T-cell epitope are critical for assessing cellular immune responses caused by tumor antigens and the discovery of T cell epitopes. Creative Biolabs offers a variety of in vivo assays using our transgenic mice to identify and characterize tumor antigens and novel T-cell epitopes. Our diverse in vivo assays can be applied to a wide range of studies and therapeutic approaches.
Prediction of T cell Epitopes by In Vivo Assays
Prediction of T cell epitopes is a critical element of successful cancer vaccines and targeted immunotherapies. T cell epitopes bound to major histocompatibility complex [MHC, also called the human leukocyte antigen (HLA) in humans] molecules activate T cells to initiate subsequent immunological orchestration. MHC class I (MHC-I) molecules typically present 8- to 11-aa peptides produced by proteasome cleavage of intracellular proteins to activate CD8+ cytotoxic T lymphocytes (CTLs), while MHC class II (MHC-II) molecules activate CD4+ T helper (Th) cells by binding to variable-length peptides from endocytic proteins. The immunogenicity of the peptides can be tested in vivo using mice that are transgenic for different HLA antigens. With a wealth of experience and a team of experts in the field of immune-oncology, Creative Biolabs provides high quality in vivo assay to predict the immunogenicity of peptides. Our in vivo assay involves several mice transgenic for different HLA antigens, as described below.
MHC I (HLA-A2) Transgenic Mice
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HLA-A2 transgenic mouse model (HHD II) provides a good animal model for the study of HLA-A2-restricted CTL responses in vivo. These animals express a single MHC-I molecule which consists of the human HLA-A2.1 a1 and a2 domains, the murine H-2Dba3, transmembrane, and cytoplasmic class I heavy chain regions, covalently linked to human b2-microglobulin, allowing for HLA-A2- restricted antigen presentation. Today, the HHD II mice have been widely used for the identification of HLA-A2.1-restricted CTL responses and are superior to the “conventional” HLA-A*0201/Kb transgenic mouse model. Therefore, HHD II mouse is an ideal model for the identification of novel immunogenic peptides. Besides, HHD II mice have been shown to be a very useful model for studying, evaluating and comparing the efficiency of different vaccine formats. |
MHC II (HLA-DR4 and HLA-DR1) Transgenic Mice
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HLA-DR1+/+/IA+/+ and HLA-DR4+/+/IE0/0 transgenic mice offer valuable models of the human CD4+ T-cell immune response and can be used to identify MHC-II peptides. Similar to MHC-I, MHC-II peptides derived from tumor-associated proteins, such as p53, can be synthesized and used to immunize DR4 and DR1 transgenic mice. For example, Müller et al. used this method to identify new p53 class II peptides. In their study, mice were immunized twice with peptides in incomplete Freund’s adjuvant, and then splenocytes were stimulated with the same peptide. After seven days, the ability of CD4+ T cells to respond specifically to peptide-pulsed DCs, tumor lysate-pulsed DCs, or tumor cells was tested. The results showed specific DR-restricted proliferation and cytokine production by splenocytes derived from p53 peptide-immunized animals. |
MHC I + MHC II Transgenic Mice
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Compared with MHC-I or II single transgenic mice, MHC-I and II double-transgenic mice allow the observation of synergy effects of MHC-I and -II molecules in immune response, which has unique advantages for studying the pathogenesis of tumors or screening anti-tumor vaccines. Many groups are developing transgenic mice with both human class I and class II molecules and knockouts of the murine class I and class II molecules. In 2004, Anthony et al. successfully generated a human MHC HLA-A2/DR1 transgenic mouse model by introducing human HLA-A2 and HLA-DR1 gene and knocking out the mouse H-2 class I and class II molecules. For this mouse, its cellular immune responses are completely restricted by human HLA molecules and are highly consistent with human cellular immune responses. Because it reflects human natural immune responses, this mouse is an ideal model for studying T cell epitopes and evaluating cellular immunity based protective vaccines. |
Benefits of Our In Vivo Assays
Our in vivo assay approach to identification and characterization of tumor antigens and novel T-cell epitopes provides:
At Creative Biolabs, our scientific team has developed broad expertise working on complex immune-oncology assays, which allows us to provide our clients with both “off-the-shelf” and custom-made assays. For more information, please feel free to contact us.
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