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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 approximately 12 and approximately 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 degrees C, soluble recombinant CD80 bound to CTLA-4 and CD28 with Kd values of 0.42 and 4 microM, respectively. Kinetic analysis indicated that these low affinities were the result of very fast dissociation rate constants (k(off)); sCD80 dissociated from CD28 and CTLA-4 with k(off) values of > or = 1.6 and > or = 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.

Original publication




Journal article


J Exp Med

Publication Date





393 - 403


Abatacept, Antigens, CD, Antigens, Differentiation, B7-1 Antigen, Base Sequence, CD28 Antigens, CTLA-4 Antigen, Humans, Immunoconjugates, Kinetics, Molecular Sequence Data, Receptors, Antigen, T-Cell