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

			Inhibition (%)
mAb	Domain	Epitope	Wild-type αLβ2	αLβ2-4a	HAαLβ2*
TS2/6	αL I	154-183	97	97	97
May.035	αL I	K197,H201	98	97	97
MHM24	αL I	K197	96	98	96
TS1/22	αL I	Q266,S270	96	96	92
TS2/14	αL I	S270,E272	99	97	14
CBR LFA-1/1	αL I	301-338	97	96	2
May.017	β2 I-like	E175, ?	98	97	3
MHM23	β2 I-like	E175	97	93	2
TS1/18	β2 I-like	R133,H332	98	88	0
YFC51	β2 I-like	R133,H332	98	87	0
CLB LFA-1/1†	β2 I-like	H332,N339	97	2	0

Wild-type and mutant K562 transfectants were assayed with and without preactivation with mAb CBR LFA-1/2, respectively. Binding to soluble, multimeric ICAM-1 in medium containing 1 mM CaCl₂ and 1 mM MgCl₂ in the presence of the indicated mAb was assayed by immunofluorescence flow cytometry. Results are given as means of three experiments.

^*α_Lβ₂ with the high-affinity K287C/K294C I domain mutation (34).

^†Binding of CLB LFA-1/1 to the α_Lβ₂-4a mutant was <5% of binding to wild-type α_Lβ₂. All other mAbs bound to α_Lβ₂-4a, high-affinity α_Lβ₂, and wild-type α_Lβ₂ transfectants equally well.