Table 2.

Binding of Fc variants to murine and human FcγRs

Affinity measurements (KD, nmol/L)
Human Fc receptorsMurine Fc receptors
WT411 (403–419)1,066 (981–1150)33 (25–41)84 (80–87)157 (144–169)79 (67–90)
1840 (32–48)99 (77–121)17 (16–17)106 (91–121)113 (106–120)19 (18–19)
  • NOTE: The low-affinity receptor hCD32B and the mouse FcγRs do not show measurable binding to monomeric human IgG1. These FcγRs were expressed in their dimeric forms because, due to avidity effect, they show measurable binding to captured hIgG1. In the case of dimeric forms of the receptors, equilibrium dissociation constant (KD) represents a relative avidity value that was used for assessment of the relative effect of mutations on the receptor binding to Fc. The average KD was based on at least two independent measurements; ranges are shown in parenthesis.