Effects of a local auxiliary protein on the two-dimensional affinity of a TCR–peptide MHC interaction

Junghans, Victoria, Chouliara, Manto, Santos, Ana Mafalda, Hatherley, Deborah, Petersen, Jan, Dam, Tommy, Svensson, Lena M., Rossjohn, Jamie ORCID: https://orcid.org/0000-0002-2020-7522, Davis, Simon J. and Jönsson, Peter 2020. Effects of a local auxiliary protein on the two-dimensional affinity of a TCR–peptide MHC interaction. Journal of Cell Science 133 (15) , jcs245985. 10.1242/jcs.245985

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Abstract

he affinity of T-cell receptors (TCRs) for major histocompatibility complex molecules (MHCs) presenting cognate antigens likely determines whether T cells initiate immune responses, or not. There exist few measurements of two-dimensional (2D) TCR–MHC interactions, and the effect of auxiliary proteins on binding is unexplored. Here, Jurkat T-cells expressing the MHC molecule HLA-DQ8-glia-α1 and the ligand of an adhesion protein (rat CD2) were allowed to bind supported lipid bilayers (SLBs) presenting fluorescently labelled L3-12 TCR and rat CD2, allowing measurements of binding unconfounded by cell signaling effects or co-receptor binding. The 2D Kd for L3-12 TCR binding to HLA-DQ8-glia-α1, of 14±5 molecules/μm2 (mean±s.d.), was only marginally influenced by including CD2 up to ∼200 bound molecules/μm2 but higher CD2 densities reduced the affinity up to 1.9-fold. Cell–SLB contact size increased steadily with ligand density without affecting binding for contacts at up to ∼20% of total cell area, but beyond this lamellipodia appeared, giving an apparent increase in bound receptors of up to 50%. Our findings show how parameters other than the specific protein–protein interaction can influence binding behavior at cell–cell contacts.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Medicine
Publisher:	Company of Biologists
ISSN:	0021-9533
Date of First Compliant Deposit:	20 August 2020
Date of Acceptance:	11 June 2020
Last Modified:	03 May 2023 02:41
URI:	https://orca.cardiff.ac.uk/id/eprint/134303

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