Inhibition of Growth of Amethopterin-Sensitive and Amethopterin-Resistant Pairs of Lymphocytic Neoplasms by Dietary Folic-Acid Deficiency in Mice

Abstract

Weanling mice were placed on one of two similar purified diets, one with folic acid, and the other without this vitamin. After mice had been maintained on these diets routinely for 6 weeks, they were given intraperitioneal injections of ascites tumor cells of lymphocytic neoplasms. Two transplantable neoplasms of strain DBA/2 origin (P288 and P388) and their respective ame-thopterin-resistant sublines (P288/AMR2 and P388/AMR1) were used. With survival time and ascites tumor cell growth used as parameters, it was found that folic-acid deficiency retarded the growth of all 4 sublines, with the most inhibitory effect of the deficiency observed in the amethopterin-resistant subline P288/AMR2. Amethopterin administration, however, did not inhibit the growth of the amethopterin-resistant sublines. The inhibition of growth of the sensitive sublines of P288 and P388 by folic-acid deficiency was much less than that afforded by amethopterin administration.