Table 2.
Differential inhibition by antibodies of binding of wild-type and open mutant αLβ2 to immobilized ICAM-1
| mAb | Epitope | % Inhibition
|
|||
|---|---|---|---|---|---|
| Wild-type
αLβ2*
|
K287C/K294C
|
||||
| 293T | K562 | 293T | K562 | ||
| RR1/1 | ICAM-1 | 96 | ND | 98 | ND |
| αL I domain | |||||
| BL5 | 119–153, 185–215 | 97 ± 1 | 98 | 91 ± 3 | 91 ± 4 |
| F8.8 | 119–153, 185–215 | 95 | 98 | 92 | 98 |
| TS2/6 | 154–183 | 97 ± 1 | 92 ± 3 | 79 ± 7 | 88 ± 5 |
| May.035 | 185–215 | 96 ± 0 | 96 ± 1 | 97 ± 1 | 93 ± 2 |
| TS1/11 | 185–215 | 94 | 97 | 45 | 41 |
| TS1/12 | 185–215 | 96 ± 3 | 97 ± 0 | 49 ± 7 | 64 ± 6 |
| TS1/22 | 250–303 | 96 | 97 ± 0 | 95 | 94 ± 3 |
| TS2/14 | 250–303 | 94 ± 2 | 96 ± 1 | 3 ± 7 | 9 ± 0 |
| 25.3.1 | 250–303 | 90 | 92 ± 0 | 4 | 3 ± 3 |
| CBR LFA-1/1 | 301–338 | 93 ± 1 | 95 ± 4 | 9 ± 2 | 3 ± 3 |
| αL β-propeller | |||||
| S6F1 | 1–57 | ND | 6 | ND | 10 |
| TS2/4 | 1–57 | ND | 7 | ND | 3 |
| β2 I-like domain | |||||
| TS1/18 | R122 or H332 | ND | 98 | ND | 6 |
| YFC51 | R122 and H332 | ND | 98 | ND | 0 |
| CLBLFA-1/1 | H332 and N339 | ND | 95 | ND | 7 |
| May.017 | E175 and ? | ND | 98 | ND | 3 |
| 6.5e | E175 | ND | 98 | ND | 6 |
| β2 C-terminal | |||||
| CBR LFA-1/7 | 345–612 | ND | 5 | ND | 6 |
| YTA-1 | β-propeller and I-like domain | ND | 99 | ND | 7 |
Binding of the transfectants to immobilized ICAM-1 was determined in the presence of the indicated antibodies. The amount of control binding was similar to that shown in Fig. 2A. Data are % inhibition ± difference from the mean of two independent experiments. For some antibodies, only one experiment was done. However, in each experiment, each antibody was repeated in triplicate, and the standard deviation of % bound cells of the triplicate samples was <4%. ND: not determined.
Wild-type αLβ2 is constitutively active in 293T cells; wild-type αLβ2 in K562 transfectants was activated by preincubation with mAb CBR LFA-1/2 at 10 μg/ml for 30 min (25).