Alpha-2 antiplasmin in acute nonlymphoblastic leukemia.

The levels of alpha-2-antiplasmin (alpha 2-AP), antithrombin III (At III) and plasminogen were studied in 21 patients with acute nonlymphoblastic leukemia (ANLL) before and after induction chemotherapy and during bone marrow cellularity recovery after the postchemotherapy aplastic phase. In the patients with M2, M3 or M4 leukemia who had clinical and laboratory evidence of DIC, the alpha 2-AP levels were very low in the initial phase of the disease but improved significantly during recovery of marrow cellularity. At III and plasminogen values were in the normal range at disease onset and showed no significant modification during the course of leukemia. Proteolytic cleavage of alpha 2-AP by granulocyte proteases, rather than hyperfibrinolysis, may be responsible for the low levels of the inhibitor in the proliferative phase of ANLL. This alpha 2-AP deficiency may well contribute to hemorrhagic diathesis in ANLL independently of the presence or absence of hyperfibrinolysis or DIC. Moreover, the lower alpha 2-AP levels observed during the proliferative phase of ANLL may relate to disease activity.