Affinity and kinetic analysis of Fcgamma receptor IIIa (CD16a) binding to IgG ligands.
Binding of pathogen-bound immunoglobulin G (IgG) to cell surface Fc gamma receptors (FcgammaRs) triggers a wide variety of effector functions. The binding kinetics and affinities of IgG-FcgammaR interactions are hence important parameters for understanding FcgammaR-mediated immune functions. We have measured the kinetic rates and equilibrium dissociation constants of IgG binding to a soluble FcgammaRIIIa fused with Ig Fc (sCD16a) using the surface plasmon resonance technique. sCD16a interacted with monomeric human IgG and its subtypes IgG1 and IgG3 as well as rabbit IgG with on-rates of 6.5 x 10(3), 8.2 x 10(3), 1.1 x 10(4) and 1.8 x 10(4) m(-1) s(-1), off-rates of 4.7 x 10(-3), 5.7 x 10(-3), 5.9 x 10(-3), and 1.9 x 10(-2) s(-1), and equilibrium dissociation constants of 0.72, 0.71, 0.56, and 1.1 mum, respectively. The kinetics and affinities measured by surface plasmon resonance agreed with those obtained from real time flow cytometry and competition inhibition binding experiments using cell surface CD16a. These data add to our understanding of IgG-FcgammaR interactions.
Li
Ping
P
Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Jiang
Ning
N
Nagarajan
Shanmugam
S
Wohlhueter
Robert
R
Selvaraj
Periasamy
P
Zhu
Cheng
C
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D058851:GPI-Linked Proteins; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D011485:Protein Binding; D011817:Rabbits; D017452:Receptors, IgG / Q000378:metabolism*; D020349:Surface Plasmon Resonance; D014162:Transfection
D015703:Antigens, CD; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D008024:Ligands; D017452:Receptors, IgG