Peptides Cleaved from Fibrinogen by Plasmin Enhance the Progression of L-1 Sarcoma in BALB/c Mice*

Crude mixtures of peptides derived from fibrinogen (LMW-FDP) were injected into BALB/c mice repeatedly before and after s.c. or i.v. injection of L-1 sarcoma cells. Treatment with LMW-FDP was followed by enhanced growth of the primary tumor. The median duration of survival of tumor-bearing mice was decreased and the number of lung metastases increased. It is concluded that LMW-FDP promote the growth of a malignant tumor. This is due to an effect on the host rather than on the tumor cells.