Alteration of Homograft Reaction by A-methopterin in Lethally Irradiated Mice Treated with Homologous Marrow

Abstract

Mice which would normally succumb to a homograft reaction following an LD98 exposure to X-irradiation and homologous marrow inoculation, may be spared if they are treated with the folic acid antagonist, A-methopterin. Using different treatment schedules, varying degrees of effectiveness from increased survival following a typical reaction, to no detectable reaction, may be obtained. Weight curves demonstrate the suppression of this reaction in hybrid male mice exposed to 800 r X-irradiation, inoculated with parental-strain marrow and treated every 48 hours with A-methopterin for 9 treatments at a dose of 1.5 mg/kg body weight Similar results were observed for female mice given A-methopterin at a dose of 3 mg/ kg body weight every 48 hours for 5 treatments. The relationship between drug toxicity and effectiveness in altering the homograft reaction is discussed.