Table 1. Inhibition by α_L I and β₂ I-like domain antibodies of multimeric ICAM-1 binding to α_Lβ₂ mutants.

			Inhibition, %
mAb	Epitope		Wild-type αLβ2	αL-E310C/β2-A210C	HA αLβ2
TS2/6	αL I domain	154–183	97 ± 2	96 ± 2	97 ± 1
May.035	αL I domain	K197, H201	98 ± 1	98 ± 0	97 ± 1
MHM24	αL I domain	K197	96 ± 2	97 ± 1	96 ± 0
TS1/22	αL I domain	Q266, S270	96 ± 1	97 ± 2	92 ± 1
TS2/14	αL I domain	S270, E272	99 ± 0	99 ± 0	14 ± 2
CBR LFA-1/1*	αL I domain	301–338	97 ± 2	2 ± 0	2 ± 1
May.017	β2 I-like domain	E175, ?	98 ± 0	70 ± 8	3 ± 2
MHM23	β2 I-like domain	E175	97 ± 2	40 ± 6	2 ± 2
TS1/18	β2 I-like domain	R133, H332	98 ± 1	4 ± 3	0 ± 2
YFC51	β2 I-like domain	R133, H332	98 ± 0	2 ± 2	0 ± 1
CLB LFA-1/.1	β2 I-like domain	H332, N339	97 ± 1	2 ± 2	0 ± 0

Wild-type α_Lβ₂ in K562 transfectants was activated by preincubation with mAb CBR LFA-1/2. Binding to soluble, multimeric ICAM-1 in medium containing 1 mM CaCl₂ and 1 mM MgCl₂ was in the presence of the indicated mAb. Results are means ± SD of three experiments. HA, high-affinity I domain mutant (8).

^*The epitope spans the linker including α_L-E310C. Binding of CBR LFA-1/1 to the α_L-E310C/β₂-A210C and HA mutants was ≈50% of binding to wild-type α_Lβ₂ (8). All other mAbs bound to α_L-E310C/β₂-A210C, HA α_Lβ₂, and wild-type α_Lβ₂ equally well (data not shown)