Quantitative estimation of elastase-alpha 1-proteinase inhibitor (E-alpha 1 PI) complex in leukemia: marked elevation in cases of acute promyelocytic leukemia.

The concentrations of elastase-alpha 1-proteinase inhibitor (E-alpha 1 PI) complex were assayed in 43 patients with various types of leukemia. Marked to moderate elevation of E-alpha 1 PI complex levels was observed in patients with acute myelocytic leukemia (AML), acute promyelocytic leukemia (APL), acute myelomonocytic leukemia (AMMoL), or chronic myelocytic leukemia (CML) at diagnosis. The ratio of E-alpha 1 PI complex concentrations in plasma to leukocyte counts markedly elevated in the patients with APL, especially. During the course of remission induction therapy, levels of E-alpha 1 PI complex decreased in parallel with decline of leukocyte counts in the patients with leukemia other than APL, however the E-alpha 1 PI complex was persistently elevated regardless of leukopenia in some patients with APL. In APL, concentrations of fibrin/fibrinogen degradation products (FDP) markedly increased even when levels of plasmin-alpha 2-antiplasmin complex were within normal limits. However, levels of E-alpha 1 PI complex usually increased in these cases. From these results, it is strongly suggested that promyelocytes contain markedly elevated amounts of elastase which participates in degradation of fibrin or fibrinogen in some cases of APL.