Force-Regulated In Situ TCR-Peptide-Bound MHC Class II Kinetics Determine Functions of CD4+ T Cells.
We have recently shown that two-dimensional (2D) and force-regulated kinetics of TCR-peptide-bound MHC class I (pMHC-I) interactions predict responses of CD8(+) T cells. To test whether these findings are applicable to CD4(+) T cells, we analyzed the in situ 3.L2 TCR-pMHC-II interactions for a well-characterized panel of altered peptide ligands on the T cell surface using the adhesion frequency assay with a micropipette and the thermal fluctuation and force-clamp assays with a biomembrane force probe. We found that the 2D effective TCR-pMHC-II affinity and off-rate correlate with, but better predict the T cell response than, the corresponding measurements with the surface plasmon resonance in three dimensions. The 2D affinity of the CD4 for MHC-II was very low, approaching the detection limit, making it one to two orders of magnitude lower than the affinity of CD8 for MHC-I. In addition, the signal-dependent cooperation between TCR and coreceptor for pMHC binding previously observed for CD8 was not observed for CD4. Interestingly, force elicited TCR-pMHC-II catch-slip bonds for agonists but slip-only bonds for antagonists, thereby amplifying the power of discrimination between altered peptide ligands. These results show that the force-regulated 2D binding kinetics of the 3.L2 TCR for pMHC-II determine functions of CD4(+) T cells.
Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332; Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332;
Jinsung
J
Hong
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110;
Stephen P
SP
Persaud
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110;
Stephen
S
Horvath
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110;
Paul M
PM
Allen
Department of Immunology and Microbiology, Emory University School of Medicine, Atlanta, GA 30332; and.
Brian D
BD
Evavold
Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332; Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332; Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 cheng.zhu@bme.gatech.edu.
Cheng
C
Zhu
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D010455:Peptides / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology*
D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D011948:Receptors, Antigen, T-Cell