Proteases during the growth of Ehrlich ascites tumor. I. The fibrinolysin system.

Component levels of the fibrinolysin system in the plasma and ascitic fluid of Swiss mice bearing Ehrlich ascites tumor cells were determined during a 15-day tumor growth time phase. During tumor growth, the concentration of plasminogen in the ascitic fluid decreased inversely to the total packed cell volume. Free plasmin was not present in the ascitic fluid nor was there any measurable plasminogen activator activity. Both antiplasmin activity and fibrinogen levels present in the fluid decreased during tumor growth. The nuclear and mitochondrial-microsomal subcellular fractions of the tumor cell exhibited plasminogen activator activity. No significant changes in the above parameters occurred in the plasma during the tumor growth period we studied.