Small molecules to manipulate peptide binding to MHC class I molecules, an optimized method for the generation of MHC tetramers by peptide exchange

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MHC (Major Histocompatibility Compex) class I molecules play a pivotal role in the antiviral immune response by presenting viral peptides to cytotoxic T cells at the cell surface. Each T cell recognizes a specific class I-peptide complex and subsequently induces apoptosis of the infected cell. These specific T cells proliferate in the course of an antiviral immune response so that the examination of a patient´s T cell pool allows the identification of the most antigenic peptides offering the possibility to predict the progress of the disease or to determine peptides applicable for immunization.So far, relevant T cells are detected with fluorescently labeled class I tetramers: Four class I molecules are folded with the test peptide of interest, biotinylated, and the class I-peptide complexes are tetramerised via fluorescently labeled streptavidin. A class I tetramer efficiently binds to its specific T cell, which can then be detected and quantified. A special type of class I tetramers are the so-called Streptamers: Here, the class I molecules carry a Strep-tag that binds to a mutagenized streptavidin (StrepTactin) with high-affinity and can be released from StrepTactin by the addition of biotin enabling reversible T cell staining.However, T cell staining with Streptamers is a sophisticated and expensive technique impeding immunological research and medical treatment. The aim of this transfer project is the optimization of T cell detection by an improved Streptamer technology based on an innovation we have developed within the scope of a DFG-funded project. In order to detect T cell populations specific for different class I-peptide complexes, each Streptamer must be generated from scratch with the respective test peptides, a procedure that takes weeks every time it has to be repeated. We, in contrast, will pre-produce master Streptamers with folding peptides, which can be exchanged with the help of dipeptides for a test peptide of interest, thereby reducing the production time of a specific Streptamer to a few hours. This innovation will not only accelerate and cheapen T cell detection but will in the future render immune therapy of viral infections more effective.Our cooperation partner, iba GmbH, is a leading supplier of products and services to the life science community based in Göttingen, Germany, and is especially well known for their Strep-tag technology. In the course of this transfer project, we and iba will together develop a prototype kit that will in the future allow each diagnostic and research lab to individually generate Streptamers with peptides of interest in a time- and cost-saving manner. Iba GmbH will later sell these kits or, alternatively, will offer T cell screenings based on that same assay. In the long term, this project will also strengthen the market position of the German company iba against international competitors, especially US american companies.