Protection of Mice by Postirradiation Treatment with a Cell-Free Component of Spleen

SummaryFractions of Ellinger's cell-free splenic extract administered following a lethal X-ray exposure resulted in 94% survival. This increased survival is greater than has previously been reported with any cell-free preparations given after radiation exposure. The protective agent was found in the second protein peak obtained by gel filtration with Sephadex G-200. The molecular weight of the protective fraction as determined by gel filtration was approximately 70,000. The relative degree of protection induced by this cell-free factor decreased with increasing X-ray doses.