Summary
Using clotting assay and radioimmunoassay (RIA), tissue factor activity (TFA) and
TF related antigen (TFR:AG) were determined in an extracellular culture medium of
HL-60 cells. After 12 h incubation, TFA and TFR:AG in the medium with endotoxin (EDX:
1 μg/ml) reached maximums which were 1.8 and 2.1 times greater than those in the medium
without EDX, respectively. In the leukemic cells of 10 patients with acute nonlymphoid
leukemia (ANLL), TFR:AG showed a significant correlation with TFA (p <0.01). On day
1 of the induction chemotherapy, TFR:AG in the 7 patients with DIC significantly increased
to 288.9 ± 153.1 ng/ml (p <0.01), whereas no increase in TFR: AG was recognized in
the 3 patients without DIC. These results suggest that TF may be released from leukemic
cells into the culture medium or blood stream, and that this may correlate with the
development of DIC.