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Measuring TCR-pMHC Binding In Situ using a FRET-based Microscopy Assay
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Monomeric class I molecules mediate TCR/CD3 epsilon/CD8 interaction on the surface of T cells

M S Block1, A J Johnson, Y Mendez-Fernandez

  • 1Department of Immunology, Mayo Graduate and Medical Schools, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.

Journal of Immunology (Baltimore, Md. : 1950)
|July 7, 2001
PubMed

Both CD8 and the TCR bind to MHC class I molecules during physiologic T cell activation. It has been shown that for optimal T cell activation to occur, CD8 must be able to bind the same class I molecule that is bound by the TCR. However, no direct evidence for the class I-dependent association of CD8 and the TCR has been demonstrated. Using fluorescence resonance energy transfer, we show directly that a single class I molecule causes TCR/CD8 interaction by serving as a docking molecule for both CD8 and the TCR. Furthermore, we show that CD3epsilon is brought into close proximity with CD8 upon TCR/CD8 association. These interactions are not dependent on the phosphorylation events characteristic of T cell activation. Thus, MHC class I molecules, by binding to both CD8 and the TCR, mediate the reorganization of T cell membrane components to promote cellular activation.

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