Novel CD8+ T Cell Antagonists Based on β2-Microglobulin

• Published in: The Journal of biological chemistry 2002-06, Vol.277 (23), p.20840-20846
• Main Authors: Glick, Meir, Price, David A., Vuidepot, Anne-Lise, Andersen, Torben B., Hutchinson, Sarah L., Laugel, Bruno, Sewell, Andrew K., Boulter, Jonathan M., Dunbar, P. Rod, Cerundolo, Vincenzo, Oxenius, Annette, Bell, John I., Richards, W. Graham, Jakobsen, Bent K.
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M201819200

The CD8 coreceptor of cytotoxic T lymphocytes binds to a conserved region of major histocompatibility complex class I molecules during recognition of peptide-major histocompatibility complex (MHC) class I antigens on the surface of target cells. This event is central to the activation of cytotoxic T lymphocyte (CTL) effector functions. The contribution of the MHC complex class I light chain, β2-microglobulin, to CD8αα binding is relatively small and is mediated mainly through the lysine residue at position 58. Despite this, using molecular modeling, we predict that its mutation should have a dramatic effect on CD8αα binding. The predictions are confirmed using surface plasmon resonance binding studies and human CTL activation assays. Surprisingly, the charge-reversing mutation, Lys58 → Glu, enhances β2m-MHC class I heavy chain interactions. This mutation also significantly reduces CD8αα binding and is a potent antagonist of CTL activation. These results suggest a novel approach to CTL-specific therapeutic immunosuppression.