Table 1: Plasminogen binding to cell surfaces of several leukemic cell lines and normal peripheral blood cells.

Cell typeCell lineageMolecules of plasminogen bound/cell ( × 1 0 6 )

NB4Promyelocytic 3 8 . 0 ± 1 . 8
KG1aMyeloblastoid 1 . 5 ± 0 . 2
K562Erythromyeloid 3 . 1 ± 0 . 2
HL-60Promyeloid 1 . 7 ± 0 . 3
U937Monocytoid 2 . 0 ± 0 . 7
THP-1Monocytoid 1 . 6 ± 0 . 2
Nalm6Pre-B-Cell 1 . 2 ± 0 . 2
Molt4Undifferentiated T cell 1 . 1 ± 0 . 4
Neutrophils 0 . 3 5 ± 0 . 0 7
Monocytes 0 . 5 8 ± 0 . 0 8
Lymphocytes 0 . 5 9 ± 0 . 0 6

Binding analyses were carried out by incubation of washed cells (2–5 × 106/mL) with radiolabeled plasminogen (100 nM) in a total volume of 200 μL for 2 hours a 4°C. Cells were then separate from the whole reaction mixture by centrifugation of aliquots in 20% sucrose solution. The specific binding of radiolabeled plasminogen was determined by subtracting counts bound in the presence of 0.15 M ε-ACA. Results are the mean ± SD of 2–4 separate experiments.