Plasma levels of elastase in BM and PB of AML patients. (A) The levels of elastase in BM and PB plasma of AML patients were determined by ELISA. (B) The levels of elastase in PB plasma of 6 healthy donors were compared with those of AML patients that showed the presence (PB blasts) or absence (no PB blasts, patients no. 3 and no. 17) of leukemic blasts in the PB and with one M0 patient with no blast present in the circulation (patient no. 1). (C) Correlation between levels of elastase and number of leukemic blasts in the PB (r = 0.6, P ≤ .01). Results indicate the mean ± SD of 2 to 3 independent experiments.