Regression of the Pliss lymphosarcoma in rats and biochemical indices in hypovitaminosis A

: It has been shown that in rats with alimentary hypovitaminosis A, with a sufficiently pronounced decrease in the content of free retinol in blood serum (below 140 ng/ml) and in the liver tissue (below 360 ng/g), there is a complete regression of Pliss's lymphosarcoma. Under the conditions indicated, retinoic acid, in contradistinction to retinol, does not promote the tumor growth. A relative and absolute reduction in blood plasma of the essential amino acids, arginine, methionine and lysine, might be one of the reasons for tumor regression under hypovitaminosis A.