Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions

Peter Jonsson, Jennifer H. Southcombe, Ana Mafalda Santos, Jiandong Huo, Ricardo A. Fernandes, James McColl, Melissa Lever, Edward J. Evans, Alexander Hudson, Veronica T. Chang, Tomas Hanke, Andrew Godkin, Paul D. Dunne, Mathew H. Horrocks, Matthieu Palayret, Gavin R. Screaton, Jan Petersen, Jamie Rossjohn, Lars Fugger, Omer Dushek & 3 others Xiao-Ning Xu, Simon J. Davis, David Klenerman

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The αβ T-cell coreceptor CD4 enhances immune responses more than 1 million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native coreceptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in 2D using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D Kd of ∼5,000 molecules/μm2. This value is two to three orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by threefold via the recruitment of Lck, with only a small, 2–20% increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore seems to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination.
Original languageEnglish
Pages (from-to)5682-5687
Number of pages6
JournalProceedings of the National Academy of Sciences
Volume113
Issue number20
DOIs
Publication statusPublished - 17 May 2016

Keywords

  • protein interactions
  • TCR phosphorylation
  • adhesion
  • T-cell activation
  • binding equilibrium and kinetics

Cite this

Jonsson, P., Southcombe, J. H., Santos, A. M., Huo, J., Fernandes, R. A., McColl, J., ... Klenerman, D. (2016). Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions. Proceedings of the National Academy of Sciences, 113(20), 5682-5687. https://doi.org/10.1073/pnas.1513918113
Jonsson, Peter ; Southcombe, Jennifer H. ; Santos, Ana Mafalda ; Huo, Jiandong ; Fernandes, Ricardo A. ; McColl, James ; Lever, Melissa ; Evans, Edward J. ; Hudson, Alexander ; Chang, Veronica T. ; Hanke, Tomas ; Godkin, Andrew ; Dunne, Paul D. ; Horrocks, Mathew H. ; Palayret, Matthieu ; Screaton, Gavin R. ; Petersen, Jan ; Rossjohn, Jamie ; Fugger, Lars ; Dushek, Omer ; Xu, Xiao-Ning ; Davis, Simon J. ; Klenerman, David. / Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions. In: Proceedings of the National Academy of Sciences. 2016 ; Vol. 113, No. 20. pp. 5682-5687.
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abstract = "The αβ T-cell coreceptor CD4 enhances immune responses more than 1 million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native coreceptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in 2D using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D Kd of ∼5,000 molecules/μm2. This value is two to three orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by threefold via the recruitment of Lck, with only a small, 2–20{\%} increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore seems to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination.",
keywords = "protein interactions, TCR phosphorylation, adhesion, T-cell activation, binding equilibrium and kinetics",
author = "Peter Jonsson and Southcombe, {Jennifer H.} and Santos, {Ana Mafalda} and Jiandong Huo and Fernandes, {Ricardo A.} and James McColl and Melissa Lever and Evans, {Edward J.} and Alexander Hudson and Chang, {Veronica T.} and Tomas Hanke and Andrew Godkin and Dunne, {Paul D.} and Horrocks, {Mathew H.} and Matthieu Palayret and Screaton, {Gavin R.} and Jan Petersen and Jamie Rossjohn and Lars Fugger and Omer Dushek and Xiao-Ning Xu and Davis, {Simon J.} and David Klenerman",
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language = "English",
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Jonsson, P, Southcombe, JH, Santos, AM, Huo, J, Fernandes, RA, McColl, J, Lever, M, Evans, EJ, Hudson, A, Chang, VT, Hanke, T, Godkin, A, Dunne, PD, Horrocks, MH, Palayret, M, Screaton, GR, Petersen, J, Rossjohn, J, Fugger, L, Dushek, O, Xu, X-N, Davis, SJ & Klenerman, D 2016, 'Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions' Proceedings of the National Academy of Sciences, vol. 113, no. 20, pp. 5682-5687. https://doi.org/10.1073/pnas.1513918113

Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions. / Jonsson, Peter; Southcombe, Jennifer H.; Santos, Ana Mafalda; Huo, Jiandong; Fernandes, Ricardo A.; McColl, James; Lever, Melissa; Evans, Edward J.; Hudson, Alexander; Chang, Veronica T.; Hanke, Tomas; Godkin, Andrew; Dunne, Paul D.; Horrocks, Mathew H.; Palayret, Matthieu; Screaton, Gavin R.; Petersen, Jan; Rossjohn, Jamie; Fugger, Lars; Dushek, Omer; Xu, Xiao-Ning; Davis, Simon J.; Klenerman, David.

In: Proceedings of the National Academy of Sciences, Vol. 113, No. 20, 17.05.2016, p. 5682-5687.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions

AU - Jonsson, Peter

AU - Southcombe, Jennifer H.

AU - Santos, Ana Mafalda

AU - Huo, Jiandong

AU - Fernandes, Ricardo A.

AU - McColl, James

AU - Lever, Melissa

AU - Evans, Edward J.

AU - Hudson, Alexander

AU - Chang, Veronica T.

AU - Hanke, Tomas

AU - Godkin, Andrew

AU - Dunne, Paul D.

AU - Horrocks, Mathew H.

AU - Palayret, Matthieu

AU - Screaton, Gavin R.

AU - Petersen, Jan

AU - Rossjohn, Jamie

AU - Fugger, Lars

AU - Dushek, Omer

AU - Xu, Xiao-Ning

AU - Davis, Simon J.

AU - Klenerman, David

PY - 2016/5/17

Y1 - 2016/5/17

N2 - The αβ T-cell coreceptor CD4 enhances immune responses more than 1 million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native coreceptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in 2D using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D Kd of ∼5,000 molecules/μm2. This value is two to three orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by threefold via the recruitment of Lck, with only a small, 2–20% increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore seems to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination.

AB - The αβ T-cell coreceptor CD4 enhances immune responses more than 1 million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native coreceptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in 2D using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D Kd of ∼5,000 molecules/μm2. This value is two to three orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by threefold via the recruitment of Lck, with only a small, 2–20% increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore seems to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination.

KW - protein interactions

KW - TCR phosphorylation

KW - adhesion

KW - T-cell activation

KW - binding equilibrium and kinetics

UR - http://www.ncbi.nlm.nih.gov/pubmed/27114505

U2 - 10.1073/pnas.1513918113

DO - 10.1073/pnas.1513918113

M3 - Article

VL - 113

SP - 5682

EP - 5687

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 20

ER -