The structurally related T cell surface molecules CD28 and CTLA-4 interact with cell surface ligands CD80 (B7-1) and CD86 (B7-2) on antigen-presenting cells (APC) and modulate T cell antigen recognition. Preliminary reports have suggested that CD80 binds CTLA-4 and CD28 with affinities (Kd values ∼12 and ∼200 nM, respectively) that are high when compared with other molecular interactions that contribute to T cell–APC recognition. In the present study, we use surface plasmon resonance to measure the affinity and kinetics of CD80 binding to CD28 and CTLA-4. At 37°C, soluble recombinant CD80 bound to CTLA-4 and CD28 with Kd values of 0.42 and 4 μM, respectively. Kinetic analysis indicated that these low affinities were the result of very fast dissociation rate constants (koff); sCD80 dissociated from CD28 and CTLA-4 with koff values of ⩾1.6 and ⩾0.43 s−1, respectively. Such rapid binding kinetics have also been reported for the T cell adhesion molecule CD2 and may be necessary to accommodate dynamic T cell–APC contacts and to facilitate scanning of APC for antigen.
CD80 (B7-1) Binds Both CD28 and CTLA-4 with a Low Affinity and Very Fast Kinetics
Address correspondence to P. Anton van der Merwe, MRC Cellular Immunology Unit, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.
We gratefully acknowledge Neil Barclay, Marion Brown, and Don Mason for providing valuable advice and critically reading this manuscript; Liz Davies for constructing the sCD80his-encoding plasmid; Marion Brown and Fabiana Horn for expression and purification of CTLA-4 Ig; and Tony Willis for performing the amino acid analyses. We thank Drs. D. Olive, R.A.W. van Lier, and K. Sagawa for kindly providing us with monoclonal antibodies listed in Table 1.
This work was supported by the United Kingdom Medical Research Council and the Wellcome Trust. D.L. Bodian was supported by the Cancer Research Fund of the Damon Runyon–Walter Winchell Foundation, Fellowship DRG-1246.
1Abbreviations used in this paper: CHO, Chinese hamster ovary; FC, flow cell; koff, dissociation rate constant; kon, association rate constant; RU, response unit; sCD80his, soluble CD80 with carboxy-terminal oligo-histidine tag; SPR, surface plasmon resonance.
P. Anton van der Merwe, Dale L. Bodian, Susan Daenke, Peter Linsley, Simon J. Davis; CD80 (B7-1) Binds Both CD28 and CTLA-4 with a Low Affinity and Very Fast Kinetics. J Exp Med 3 February 1997; 185 (3): 393–404. doi: https://doi.org/10.1084/jem.185.3.393
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