Are There Implications for the Retinoic Acid Syndrome?
. . . . . 139-149 ABSTRACT. Differentiation therapy for acute promyelocytic leukemia (APL) using all-trans-retinoic acid (ATRA) has improved the prognosis of the disease. ATRA therapy also causes a newly recognized clinical syndrome, the “retinoic acid syndrome” (RAS), which can be successfully managed with dexamethasone. Because aberrant function of maturing leukemic granulocytes may cause this syndrome, and because dexamethasone is useful clinically, we studied functional properties of maturing HL60 cells cultured in the presence and absence of dexamethasone. HL60 cells were cultured for 4 days with ATRA and studied daily to determine acquisition of mature neutrophil-like properties including phagocytosis, NBT reduction, actin polymerization, chemotaxis and adhesion molecule expression. Undifferentated HL60 cells could not polymerize actin or reduce NBT, and exhibited only a minimal abilty to undergo chemotaxis or ingest latex beads. Following 4 days of maturation with ATRA, the cell
