Immunization with Klebsiella pneumoniae prior to x-irradiation increased the resistance of mice to challenge with an aerosol of the living organisms. This protective effect of preradiation immunization was not destroyed at sublethal to near midlethal levels of exposure (levels at which mortality resulting from overwhelming infections are implicated as an important cause of death). The results presented show that a large total irradiation dose, given in increments, is far less detrimental to the host defenses than the same dose acutely administered.


This study was supported by funds provided under contract AF 18(600)946 with the USAF School of Aviation Medicine, Randolph Field, Texas.

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