A Case of Acute Promyelocytic Leukemia with A High Thromboplastic Activity in the Cell Extract

Abstract

Acute promyelocytic leukemia (APL) is known to be a severe hemorragic disorder, which is probably due to increased fibrinolytic activity, or to D. I. C. There are a few reports suggesting the presence of thromboplastin-like materials in the promyelocytic cells, and this may induce D. I. C.
Recently we had a case of typical APL. Laboratory tests revealed hypofibrinogenemia, thrombocytopenia, moderate titer of F. D. P., prolongation of prothrombin time and serial thrombin time, and presence of a number of promyelocytic cells in bone marrow.
By combined administration of prednisolone, vincristine sulfate, daunorubicin, and other drugs, a complete remission was obtained.
After 3 months, patient relapsed and we studied thromboplastic activity of APL cell extracts.
The method of estimating thromboplastic activity of tumor cell extracts is as follows.
White blood cells consisting of more than 90% of promyelocytic cells were obtained by venipuncture and bone marrow puncture. To remove blood coagulation factors and thrombocytes, leukemic cells were cultured for 2∼5 days. Cultured cells and medium harvested were used for study. Results were as follows.
1) Recalcification time of normal and hemophilic plasma was more accelerated by the extracts of APL cells than that of control cells (ALL, AML or nomal leukocytes).
2) Medium harvested after APL cell culture did not accelerate recalcification time of normal plasma.
These evidences seemed to suggest that promyelocytic cells of APL contain a large amount of thromboplastin-like materials.