MHC Class II Peptide Thioredoxin Motif for CD4+ T Cell Detection
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Solution Overview
Problem
Current methods for detecting and isolating CD4+ T cells are inefficient due to the low affinity of T cell receptors (TCRs) for peptide-MHC class II complexes, particularly in complex body fluids, limiting their effectiveness in autoimmune diseases, cancer diagnosis, and vaccination evaluation.
Innovation Solution
The use of peptides comprising an MHC class II restricted T cell epitope with a thioredoxin motif within flanking residues, either immediately adjacent or separated by a linker, enhances the binding affinity of MHC class II molecules to CD4+ T cells, allowing for specific and sensitive detection and isolation of CD4+ T cells using MHC class II molecules as isolated complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional peptide-MHC class II complexes are used for detection, then the method is simple to implement, but the binding affinity to CD4+ T cells is low resulting in poor detection sensitivity
Solution Approach 1:
The invention modifies the peptide structure by introducing a thioredoxin motif (CXXC sequence) into the flanking residues of the epitope, changing the chemical parameters of the peptide-MHC complex to achieve higher binding affinity and detection sensitivity without fundamentally altering the detection methodology
Solution Approach 2:
The invention creates a composite peptide structure combining the epitope sequence with the thioredoxin motif, forming a hybrid molecule that integrates both antigen recognition capability and enhanced binding properties, resulting in superior detection performance
2Productivity
If TCR low affinity for peptide-MHC complexes is accepted, then the natural immune recognition process is maintained, but detection efficiency in complex body fluids becomes insufficient
Solution Approach 1:
The invention enhances the local binding properties at the peptide-MHC-TCR interface by introducing the thioredoxin motif, which specifically improves affinity in the binding region without altering the overall immune recognition mechanism or TCR specificity
3Measurement precision
If soluble MHC multimers (dimers, tetramers, pentamers) are used to increase sensitivity, then detection capability is improved, but affinity limitations persist particularly for naive T cells
Solution Approach 1:
The invention changes the affinity parameter of the peptide-MHC complex by incorporating the thioredoxin motif, enabling reliable detection of naive T cells with low-frequency occurrence that have limited TCR affinity, thereby overcoming the affinity bottleneck of conventional multimer approaches
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high-affinity and specific detection of CD4+ T cells, allowing for more sensitive diagnostic methods and the isolation of CD4+ T cells in higher numbers and purity, even in complex samples like body fluids, and facilitates their manipulation for therapeutic purposes.
Implementation Method 1
enhances the binding affinity of MHC class II molecules to CD4+ T cells
Data Source
AI summary
The present invention relates an in vitro method for detecting class II restricted CD4+ T cells in a sample. Herein a sample is contacted with an isolated complex of an MHC class II molecule and a peptide. This peptide comprises an MHC class II restricted T cell epitope of an antigenic protein and immediately adjacent thereof, or separated by a linker of at most 7 amino acids a sequence with a [CST]-xx-C or C-xx-[CST] motif. CD4+ T cells are detected by measuring the binding of the complex with cells in the sample, wherein the binding of the complex to a cell is indicative for the presence of CD4+ T cells in the sample. The present invention further relates to an isolated complex of an MHC Class II molecule and a peptide comprising an MHC class II restricted T cell epitope of an antigenic protein and immediately adjacent thereof, or separated by a linker of at most 7 amino acids a sequence with a [CST]-xx-C or C-xx-[CST] motif.