Proteases during the growth of Ehrlich ascites tumor. II. The kallikrein-kinin system.

Ascitic fluid and ascites tumor cells from Swiss mice bearing Ehrlich ascites tumor were assayed for components of the kallikrein-kinin system at various times during tumor growth. Changes in component levels were correlated with those in the plasma. Ascitic fluid contained an acetone-activated prekallikrein that increased in concentration during tumor growth and reached peak levels during the 7th-10th day post transplant. No free kinin activity was present in the ascitic fluid. During tumor growth, kininogen levels increased in parallel with prekallikrein levels. The ascitic fluid also contained a kinin-destroying activity that was initially high during the early phase of tumor growth. Tumor cell fractions, prepared by ultracentrifugal techniques, had no kinin-forming activity while possessing kinin-destroying activity that was localized in the soluble protoplasmic protein and nuclear fractions. The kinin-forming activity of the ascitic fluid resembled that of the plasma with respect to pH optima, kinetics of kinin formation, and effect of protease inhibitors. The kininase activity of both ascitic fluid and plasma differed from that of the tumor cell fractions.