ANTIBODIES THAT ACTIVATE BETA-2 INTEGRINS CAN GENERATE DIFFERENT-LIGAND BINDING STATES

A human erythroleukemic cell line (K562) that does not normally expres s beta 2 integrins has been transfected with the genes encoding these integrins. The resulting cell Lines show minimal background adhesion b ut can be stimulated to bind to appropriate substrates when activated with either of two different antibodies to CD18. The two antibodies ap pear to generate different ligand binding states in LFA-1 such that di fferent members of the ICAM family are recognized. Antibody-activated complement receptor type 3 and p150,95-transfected cells bind protein- coated surfaces, although they require slightly different activation c onditions for optimal binding.