Table 1.
Binding of CAP-100 to FcR
| KD(M)/relative binding* | |||
|---|---|---|---|
| Fc Receptor | CAP-100 | Control IgG1 | Control IGg4 |
| CD64 | 1.38E-09 (++++) | 3.28E-09 (++++) | 9.16E-09 (++++) |
| CD16A (176Phe)/FcγRIIIA176Phe ** | 3.01E-07 (+++) | 4.68E-06 (++) | - |
| CD16A (176Val)/FcγRIIIA176Val | 1.46E-07 (+++) | 1.51E-06 (++) | - |
| CD16B/FcγRIIIB | 7.92E-07 (+++) | 6.17E.06 (++) | - |
| CD32A (167Arg)/FcγRIIA167Arg | 3.47E-06 (++) | 1.03E-05 (+) | - |
| CD32A (167His)/FcγRIIA167His | 5.54E-06 (++) | 1.03E-05 (+) | - |
| CD32B/FcγRIIB | 8.24E-06 (++) | 1.91E-05 (+) | 3.26E-05 (+) |
| FcRn (pH 6.0) | 1.27E-06 (++) | 1.34E-06 (++) | 3.38E-06 (++) |
| FcRn (pH 7.4) | - | - | - |
*The relative binding affinity scale is defined as follows: ++++ (10−8–10−9); +++ (10−7); ++ (10−6); + (10−5); ± (detectable binding); – (no detectable binding). As controls (both positive and negative, depending on the receptor and the assay) wild-type IgG1 and IgG4 were included. ** Position 176, or 167 including the signal peptide in the amino acid count. For FcγR, tests conducted at 5 point three-fold dilution of purified antibodies titrated 0.411 nM to 33.33 nM. For FcRn, at seven point two-fold dilutions from 4000 nM to 62.5 nM (4000 nM to 1000 nM for pH 6.0). For high affinity receptors (FcγRI), 1:1 kinetic analysis was used. For low affinity FcγRII and FcγRIII receptors, and for FcRn, steady state affinity analysis was used.