Engineering the binding properties of the T cell receptor:peptide:MHC ternary complex that governs T cell activity.
The potency of a T cell is determined in large part by two interactions, binding of a cognate peptide to the MHC, and binding of the T cell receptor (TCR) to this pepMHC. Various studies have attempted to assess the relative importance of these interactions, and to correlate the corresponding binding parameters with the level of T cell activity mediated by the peptide. To further examine the properties that govern optimal T cell activity, here we engineered both the peptide:MHC interaction and the TCR:pepMHC interaction to generate improved T cell activity. Using a system involving the 2C TCR and its allogeneic pepMHC ligand, QL9-L(d), we show that a peptide substitution of QL9 (F5R), increased the affinity and stability of the pep-L(d) complex (e.g. cell surface t(1/2)-values of 13 min for QL9-L(d) versus 87 min for F5R-L(d)). However, activity of peptide F5R for 2C T cells was not enhanced because the 2C TCR bound with very low affinity to F5R-L(d) compared to QL9-L(d) (K(D)=300 microM and K(D)=1.6 microM, respectively). To improve the affinity, yeast display of the 2C TCR was used to engineer two mutant TCRs that exhibited higher affinity for F5R-L(d) (K(D)=1.2 and 6.3 microM). T cells that expressed these higher affinity TCRs were stimulated by F5R-L(d) in the absence of CD8, and the highest affinity TCR exhibited enhanced activity for F5R compared to QL9. The results provide a guide to designing the explicit binding parameters that govern optimal T cell activities.
Bowerman
Natalie A
NA
Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL 61801, USA.
Crofts
Terence S
TS
Chlewicki
Lukasz
L
Do
Priscilla
P
Baker
Brian M
BM
Christopher Garcia
K
K
Kranz
David M
DM
D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D008285:Major Histocompatibility Complex / Q000276:immunology*; D051379:Mice; D010455:Peptides / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D015202:Protein Engineering; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020349:Surface Plasmon Resonance; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014162:Transfection
D010455:Peptides; D011948:Receptors, Antigen, T-Cell