Comparative Study on the Effect of RES-Stimulating and Blockading Agents on the Immunological Response after Irradiation

Effects of carbon particles and bacterial endotoxin on the immunological recovery after irradiation were compared in relation to the radioprotective effects of the agents. When mice were injected with 10 mg of carbon particles which were sufficient to protect the animals from radiation-induced death, 24 hr prior to the administration of sheep red blood cells, the recovery of immune response to the antigen was not significantly affected. Administration of 1 mg carbon particles caused a slight enhancement of immune response. Previous treatment of animals with endotoxin resulted in a significant suppression of immune response regardless of irradiation, the degrees of suppression depending on the dose given. These results strongly suggest that the radioprotective effect of carbon or endotoxin-treatment is attributable to the apparent RES-blockade and to the enhancement of hemopoietic recovery rather than to the enhancement of immunological recovery after irradiation.