Table 3.
Binding kinetics of mouse 3F8 and hu3F8 antibodies to human FcγRII (CD32)
| Antibody | kon (1/Ms) | SD | koff (1/s) | SD | KA=kon/koff | koff (relative to CD32A-131R) | KA (relative to CD32A-131R) | |
|---|---|---|---|---|---|---|---|---|
| mouse 3F8 (IgG3) | CD32A-131R | 2.59E+04 | 9.31E+03 | 3.63E-01 | 2.36E-02 | 7.15E+04 | 1 | 1 |
| CD32A-131H | 1.90E+04 | 3.58E+03 | 1.10E+00 | 8.27E-02 | 1.73E+04 | 3.02 | 0.24 | |
| CD32B | 1.15E+04 | 1.60E+03 | 2.03E+00 | 3.78E-01 | 5.66E+03 | 5.6 | 0.08 | |
|
| ||||||||
| hu3F8 (IgG1) | CD32A-131R | 1.49E+05 | 4.38E+04 | 4.06E-01 | 4.94E-02 | 3.68E+05 | 1.12 | 5.15 |
| CD32A-131H | 2.70E+05 | 9.48E+03 | 4.27E-01 | 3.59E-02 | 6.31E+05 | 1.18 | 8.83 | |
| CD32B | 2.86E+04 | 1.63E+04 | 3.41E-01 | 2.63E-01 | 8.37E+04 | 0.94 | 1.17 | |
*
Kinetics of FcγRII (CD32) interaction with mouse 3F8 and hu3F8 were measured using a Biacore T100 biosensor and CM5 sensor chips (Biacore AB of GE Healthcare, Uppsala, Sweden). Toward the CD32A-131R allele, 3F8 had 2.67 fold slower off rate (koff), and nearly 3-fold higher binding affinity (Ka) than toward CD32A-131H. For hu3F8, the high affinity allele was 131-H. Affinity for CD32B was much lower for mouse 3F8 than for hu3F8.