EFFECT OF ALL-TRANS-RETINOIC ACID (ATRA) ON THE ADHESIVE AND MOTILITYPROPERTIES OF ACUTE PROMYELOCYTIC LEUKEMIA-CELLS

All trans-retinoic acid (ATRA) induces complete remission in acute-pro myelocytic-leukemia (APL) patients, This study investigated the adhesi ve properties of APL cells for the endothelium and the extracellular m atrix, their motility and the effect of ATRA on these functions, Blast s from 7 APL patients adhered to resting and IL l-activated endotheliu m, to the same degree as normal PMN, Adhesion was partially mediated b y ICAM-1 and, for IL-l-activated endothelium, by VCAM-1 and E-selectin , These cells showed less adhesiveness for the matrix than PMN, althou gh they maintained the same substrate preference: they adhered to fibr onectin and thrombospondin, but not to laminin and type-IV collagen, E xposure to ATRA in vitro (I mu M for 48 to 96 hr) increased the adhesi veness of APL cells; this effect was particularly evident in the case of sub-endothelial matrix and fibronectin, A similar increment in adhe siveness was observed when comparing cells from 2 patients before and after treatment with ATRA, APL cells migrated in response to fMLP and motility was increased by ATRA, In conclusion, APL cells were less adh esive to the matrix than PMN, but treatment with ATRA considerably enh anced their adhesive properties, This could be important in determinin g the efflux of leukemic cells from the bone marrow and their tissue i nfiltration during ATRA therapy. (C) 1997 Wiley-Liss, Inc.