Prolongation of Homograft Survival in Mice with Single Doses of Cyclophosphamide

Abstract

IT is customary, in prolonging the survival of homografts with a chemical agent, to give frequent doses of the agent over a prolonged period. Effective agents are generally toxic, and their use is attended by considerable mortality, in both laboratory animals and man. The immune response is not uniformly susceptible to inhibition by these agents throughout its course¹, nor is it uniformly active. It is likely, therefore, that dose-schedules not closely adapted to this changing sensitivity and activity of the immune response may, on one hand, subject the recipient to unnecessary toxicity and, on the other, fail to attack the immune response sufficiently during its most vulnerable period. It is therefore of some importance to establish the principles on which optimum dose-schedules may be based.