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 |
| 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 Rmax) 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.