Frontline: Optimal T cell activation requires the engagement of CD6 and CD166.
The T cell surface glycoprotein, CD6 binds CD166 in the first example of an interaction between a scavenger receptor cysteine-rich domain and an immunoglobulin-like domain. We report that in human these proteins interact with a K(D) =0.4-1.0 microM and K(off) > or =0.4-0.63 s(-1), typical of many leukocyte membrane protein interactions. CD166 also interacts in a homophilic manner but with around 100-fold lower affinity (K(D) =29-48 microM and K(off) > or = 5.3 s(-1)). At concentrations, that will block the CD6/CD166 interaction, soluble monomeric CD6 and CD166 inhibit antigen-specific human T cell responses. This is consistent with extracellular engagement between CD6 and CD166 being required for an optimal immune response.
Hassan
Namir J
NJ
Sir William Dunn School of Pathology, University of Oxford, Oxford, GB.
Barclay
A Neil
AN
Brown
Marion H
MH
D020410:Activated-Leukocyte Cell Adhesion Molecule / Q000276:immunology*; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D000938:Antigen-Presenting Cells / Q000276:immunology; D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D016133:Polymerase Chain Reaction; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology*
D020410:Activated-Leukocyte Cell Adhesion Molecule; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C062279:CD6 antigen