Immunogenicity is an important issue related to protein therapy, and T-cell-dependent (Td) immunology related to immunogenicity of therapeutic products is an important research direction. Peptide based cancer immunotherapy relies on the identification of epitopes recognized by T-lymphocytes. Such identification can be determined by in vitro techniques of animal and human models. Secondly, in view of the complexity and high throughput of existing in silico tools and the availability of accurate in vitro validation tests, it may be easy to accurately predict the immunogenicity of therapeutic protein products and more quickly translate research findings into clinical success. At present, Creative Biolabs has the ability to provide in vitro assay services to screen for the immunogenicity of predicted T-cell epitopes.
Fig.1 Example roadmap for immunogenicity prediction. (Jawa, 2013)
Human Leukocyte Antigen (HLA) Stabilization Assay
It has been shown that the response of cells to protein therapeutic antigens depends on the binding of T cell epitope to major histocompatibility complex (MHC), the appearance of MHC epitope complex on the cell surface and the recognition of the complex by effector or regulatory T-cells (Treg). This interaction can be evaluated in MHC or HLA binding analysis. Due to the high polymorphism of HLA and the problem of tumor immune evasion, it is necessary for researchers to select different epitopes and evaluate their stability. In the experiment, the protein sequence of peptides with high binding affinity with different HLA molecules can be used to predict the immunogenicity of tumor associated antigens (TAAs).
T-Cell Sensitization Experiments
Since the molecular cloning of melanoma-associated antigen, the molecular identification and characterization of T cell epitopes in novel TAA have developed rapidly. In vitro monitoring of antigen-specific T cell sensitivity is a method for the detection of T cell epitopes, which generally involves the measurement of proliferation by radiolabeled thymidine incorporation or release of cytokines, such as interleukin-2 (IL-2) or interferon γ (IFN γ). At present, we can provide ELISpot technology, which is one of the most sensitive methods to detect the response of T cells to therapeutic proteins, because it can detect single T cells directly from spleen cells or peripheral blood, and allow to detect the release of anti-specific cytokines.
In order to induce TD antibody response to antigens, it is usually necessary to coordinate several events in specific areas of secondary lymphoid organs. The first step in this process is to internalize antigens through specialized antigen-presenting cells (APCs), such as dendritic cells (DCs). Mature APCs process antigens into peptides (epitopes), which are then presented to naïve T cells via MHC class II molecules on the surface of APCs. Based on the important role of APC in antigen expression, the effective selection and determination of APC are of great significance in determining T cell epitopes and predicting tumor-specific immune response.
Fig.2 Overview of the role of the T-cell in the antibody response. (De Groot, 2007)
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References
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