Interaction between the CD8 coreceptor and major histocompatibility complex class I stabilizes T cell receptor-antigen complexes at the cell surface.
The off-rate (k(off)) of the T cell receptor (TCR)/peptide-major histocompatibility complex class I (pMHCI) interaction, and hence its half-life, is the principal kinetic feature that determines the biological outcome of TCR ligation. However, it is unclear whether the CD8 coreceptor, which binds pMHCI at a distinct site, influences this parameter. Although biophysical studies with soluble proteins show that TCR and CD8 do not bind cooperatively to pMHCI, accumulating evidence suggests that TCR associates with CD8 on the T cell surface. Here, we titrated and quantified the contribution of CD8 to TCR/pMHCI dissociation in membrane-constrained interactions using a panel of engineered pMHCI mutants that retain faithful TCR interactions but exhibit a spectrum of affinities for CD8 of >1,000-fold. Data modeling generates a "stabilization factor" that preferentially increases the predicted TCR triggering rate for low affinity pMHCI ligands, thereby suggesting an important role for CD8 in the phenomenon of T cell cross-reactivity.
Wooldridge
Linda
L
T Cell Modulation Group, Nuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, South Parks Road, Oxford OX1 3SY, United Kingdom.
van den Berg
Hugo A
HA
Glick
Meir
M
Gostick
Emma
E
Laugel
Bruno
B
Hutchinson
Sarah L
SL
Milicic
Anita
A
Brenchley
Jason M
JM
Douek
Daniel C
DC
Price
David A
DA
Sewell
Andrew K
AK
D000941:Antigens / Q000737:chemistry; D001703:Biophysics / Q000379:methods; D019921:Biotinylation; D016827:CD8 Antigens / Q000096:biosynthesis / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D000939:Epitopes / Q000737:chemistry; D005434:Flow Cytometry; D005805:Genes, MHC Class I / Q000235:genetics*; D005818:Genetic Engineering; D015497:HIV-1 / Q000378:metabolism; D004854:Herpesvirus 4, Human / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008024:Ligands; D008956:Models, Chemical; D009154:Mutation; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors
D000941:Antigens; D016827:CD8 Antigens; C067361:CD8 receptor; D000939:Epitopes; D008024:Ligands; D011948:Receptors, Antigen, T-Cell