Spatial coordination of CD8 and TCR molecules controls antigen recognition by CD8+ T-cells.
The interactions between the TCR and peptides bound to class I MHC encoded molecules (pMHC) and a mechanism for CD8 cooperation in this process are reviewed. Observation of two TCR/CD8 populations with different lateral diffusion rate constants as well as two distinct association phases of class I MHC tetramers ((pMHC)4) with T-cells suggest that the most efficient pMHC-T-cell association route corresponds to a fast tetramer binding to a colocalized CD8/TCR population, which apparently resides within membrane rafts. Thus, ligand-cell association starts by pMHC binding to the CD8. This rather fast step promotes pMHC association with CD8-proximal TCRs and thereby enhances the overall association process. The model suggests that this raft-associated CD8-TCR subpopulation is responsible for evoking T-cell activation.
Pecht
Israel
I
Department of Immunology, The Weizmann Institute of Science, 76100 Rehovot, Israel. israel.pecht@weizmann.ac.il
Gakamsky
Dmitry M
DM
D016827:CD8 Antigens / Q000276:immunology / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000276:immunology / Q000378:metabolism; D006801:Humans; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism*
D016827:CD8 Antigens; D015395:Histocompatibility Antigens Class I; D011948:Receptors, Antigen, T-Cell