Suppression of the Immune Response by Drugs in Combination

Abstract

Combinations of purine with pyrimidine analogs were tested for their effects on formation in mice of hemagglutinins to red blood cells. Greater than additive effects were obtained with 6-mercaptopurine and thioguanine in combination with 5-bromodeoxyuridine, 4-thiodeoxyuridine, 5-acetoxy-uracil and 6-azauracil plus urethan. 5-Bromodeoxyuridine is notable for the magnitude of the ratio of maximum tolerated dose to minimum effective dose.