936 PROCOAGULANT (PC) AND PLASMINOGEN ACTIVATOR (PA) FUNCTION OF CHILDHOOD LEUKEMIC BLASTS

Abstract

The incidence and etiology of coagulopathy in childhood acute leukemia (AL) have not been well characterized. We have studied 11 children with AL prospectively at the time of diagnosis or relapse. A DIC screen, fibrinopeptide A (FPA) assay and assays of blast cell procoagulant (PC) and plasminogen activator (PA) were performed. Patients were evaluated for clinical prognostic features, blast cell morphology and surface markers. Blast cells were separated on Ficoll-Hypaque and then used as a source of procoagulant material in normal plasma and factor VIII, X and VII deficient plasma. Fibrinolytic activity was measured using the substrate S-2251 with des-fibrin I. We found: Overt laboratory evidence of DIC was present at diagnosis and worsened after therapy in one patient with ALL. This patient's blasts produced the highest level of procoagulant material. From these preliminary data, we conclude: 1. Coagulation abnormalities are common in childhood AL. 2. FPA levels are frequently increased in childhood AL. 3. Some leukemic cells produce potent procoagulant activity which may be associated with overt DIC. 4. ALL cells also frequently produce a plasminogen activator. 5. Production of PC and/or PA by blast cells was not clearly related to morphologic or immunologic characteristics.