Table 1.

Surface plasmon resonance analysis of murine, canine, and human FcRn binding with rFVIIIFc and human IgG1

Fc sample*	FcRn	FcRn density, RU	EC50, nM†	Rmax, RU
rFVIIIFc	Murine	370	< 1.5‡	581.4
rFVIIIFc	Canine	367	8.6	499.3
rFVIIIFc	Human	369	33.4	365.4
Human IgG1	Murine	378	< 22.4‡	320.0
Human IgG1	Canine	367	196.3	282.2
Human IgG1	Human	378	558.4	211.0

^*rFVIIIFc or IgG1 were injected over a flowcell to which various FcRn molecules were chemically conjugated at approximately equal densities (∼ 370 RU).

^†EC₅₀ values (50% of R_max) were the average derived from nonlinear regression analysis of the binding response curves fitted to 16 analyte concentrations (0.0625-2000nM) repeated in duplicate (supplemental Figure 1, available on the Blood Web site; see the Supplemental Materials link at the top of the online article).

^‡Due to the high affinities, the low binding curves at low analyte concentrations did not reach equilibrium under the normal operating conditions of the instrument.