Table 1.
Binding properties of bivalent or bispecific Fab-like antibodies
| VHH αNKG2D | KDapp (nM) on rNKG2D |
KDapp (nM) on NK cells |
KDapp (nM) on BT-474 cells |
||
|---|---|---|---|---|---|
| bvFab | bsFab | bvFab | bsFab | bsFab | |
| AR3 | 0.2 ± 0.06 | 25 ± 9 | 0.40 ± 0.07 | 25 ± 8 | 102 ± 17 |
| AR6 | 0.3 ± 0.12 | 1.3 ± 0.5 | 0.40 ± 0.07 | 13 ± 5 | 101 ± 13 |
| AR11 | 0.4 ± 0.17 | 5 ± 1 | 6 ± 3 | ND>100 | 104 ± 14 |
| AR18 | 12 ± 4 | ND | 20 ± 4 | ND | 69 ± 8 |
| AR19 | 0.50 ± 0.10 | 12 ± 6 | 1.65 ± 0.48 | 30 ± 6 | 89 ± 12 |
| AR20 | 0.3 ± 0.05 | 7 ± 1 | 3.2 ± 0.95 | ND | 94 ± 19 |
| AR23 | 0.4 ± 0.13 | 20 ± 1 | 0.30 ± 0.09 | 20 ± 6 | 92 ± 23 |
Apparent affinities of bvFabs and bsFabs were determined by ELISA on recombinant NKG2D and by flow cytometry on expanded human NK and BT-474 HER2-positive cells. Values of KDapp (nM) are means ± SEM of independent experiments. ND = Values not determined due to the absence of a plateau.