Experimental Alteration of the Ability of Tumor Cells to Lyse Plasma Clots in vitro ∗

Abstract

Summary

1. Mouse Sarcoma 180 cells, in the presence of mammalian serum, cause lysis of chicken plasma clots. 2. Mammalian aqueous humor has slight influence on the fibrinolytic process. 3. When Sarcoma 180 is grown in the presence of avian serum, no lysis occurs. If a sufficient quantity of chicken serum is added to a supernatant fluid containing mammalian serum there is a decrease in the amount of clot lysis. 4. Lysis of the plasma clot by Sarcoma 180 does not occur when mammalian serum previously heated to 56°C for 3 hours is used, or when all serum is omitted from the supernatant. 5. The different degrees of lysis obtained when sera from various mammalian orders are used may be due to differences in the amount of pronbrinolysin contained in the various sera. 6. There are two factors necessary for the lytic mechanism, tentatively classified as a pronbrinolysin from the serum, and an activator of the pronbrinolysin derived from the tissue.