Antilymphoma Activity of L-Asparaginase In Vivo: Clearance Rates of Enzyme Preparations From Guinea Pig Serum and Yeast in Relation to Their Effect on Tumor Growth

Abstract

Following evidence that L-asparaginase in guinea pig serum possesses antilymphoma properties, purified L-asparaginase was obtained from yeast and tested on the growth of the guinea pig serum-sensitive Lymphoma 6C3HED in C3H mice. No inhibition of the tumor resulted. A probable explanation was found in the extremely rapid rate of clearance of this enzyme in the mouse. Whereas guinea pig serum L-asparaginase persisted in the blood in considerable amount for 3 or more days after intravenous injection, the yeast enzyme was almost completely cleared in less than 1 hour. Ultracentrifugal studies suggested that the yeast L-asparaginase was in the form of molecular aggregates, of a kind likely to be taken up by the reticuloendothelial system with great avidity.