Differential Regulation of Leukocyte Function-Associated Antigen-ll

Activation of integrin and organization of cytoskeletal proteins are highly regulated in cell adhesion and aggregation. The interaction of leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecules-I (CAM-1) mediates cell adhesion and aggregation, which facilitate leukocyte trafficking to inflamed tissues and augment effector functions. We investigated how LFA-l/ICAM-l -mediated adhesion and aggregation are regulated in HL-60 cells induced to differentiate into neutrophils by retinoic acid (RAJ. Uninduced HL-60 cells did not bind to CAM-1 even with stimulation by 12-0-tetradecanoyl phorbol-l3-acetate, although they express LFA-1 on the cell surface. When cultured with RA for 24 hours, HL-60 cells were able to adhere to ICAM-1 constitutively. The induction of adhesion did not accompany any change in surface density of LFA-1, indicating that the avidity of LFA-1 was in creased. The change in its avidity required de novo synthesis of proteins. Although