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Measuring interactions of MHC class I molecules using surface plasmon resonance
S N Khilko1, M T Jelonek, M Corr
1Molecular Biology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA.
Journal of Immunological Methods
|June 14, 1995
Summary
This study developed model systems to analyze molecular interactions involving major histocompatibility complex (MHC)-encoded molecules, revealing binding kinetics crucial for T cell activation. Understanding these interactions provides insight into T cell stimulation mechanisms.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Major histocompatibility complex (MHC)-encoded molecules are critical for immune responses, presenting peptides to T cell receptors.
- Understanding the molecular interactions between MHC molecules, peptides, antibodies, and T cell receptors is essential for deciphering immune recognition.
- Previous methods lacked detailed kinetic analysis of these complex molecular interactions.
Purpose of the Study:
- To develop and utilize model systems for examining molecular interactions involving MHC class I (MHC-I) molecules.
- To characterize the binding kinetics of MHC-I/peptide, MHC-I/antibody, and T cell receptor (TCR)/MHC-I/peptide interactions.
- To gain insights into the initial molecular events governing T cell stimulation.
Main Methods:
- Development of genetically engineered soluble MHC-I molecules, synthetic peptides, monoclonal antibodies (mAbs), and solubilizable TCRs.
- Application of surface plasmon resonance (SPR) with dextran-modified gold biosensors for direct binding assays.
- Steric mapping of the MHC-I peptide-binding site using immobilized peptides with cysteine substitutions.
- Kinetic binding studies to determine association (kass) and dissociation (kdis) rate constants.
Main Results:
- MHC-I/peptide interactions exhibit low to moderate association and very slow dissociation rates (kass ~5000-60000 M-1 s-1, kdis ~10(-4)-10(-6) s-1), supporting prolonged cell surface presence.
- Interactions of mAbs with MHC-I molecules show moderate association and dissociation rate constants (kass ~10(4)-10(6) M-1 s-1, kdis ~10(-2)-10(-4) s-1).
- TCR/MHC-I-peptide interactions are characterized by faster dissociation rates (kdis ~10(-2) s-1) compared to MHC-I/peptide binding, resembling antibody-antigen kinetics.
Conclusions:
- The developed SPR-based model systems enable detailed kinetic analysis of crucial molecular interactions in T cell recognition.
- The distinct kinetic profiles of MHC-I/peptide, antibody/MHC-I, and TCR/MHC-I interactions highlight specific molecular recognition mechanisms.
- These findings provide valuable insights into the molecular basis of T cell activation and immune response initiation.