Whole-body x-irradiation and amyloidosis

The development of amyloidosis secondary to irradiation and casein injection was studied in C3H mice. One group of mice received an initial whole- body dose of 316 r followed by weekly doses of 185 r. After 6 weeks, some of the mice were injected every other day with 1 ml 5% casein solution. Other mice were given only casein injections. Three to 5 weeks after beginning the injections, histologic examination was made of liver, spleen, heart, kidney, and intestine. In animals receiving radiation alone, parenchymal degeneration in liver and kidney, as well as extensive necrosis in spleen, was seen but no evidence of amyloid was found in any organ. Severe amyloidosis was present in organs of 50% of mice given only casein injections, and was first seen 3 weeks after the injections began. In mice receiving both irradiation and injections, the casein was less well tolerated and in many cases caused death. Amyloid tended to be deposited in the same sites that showed degeneration and necrosis after irradiation alone. It was most severe in spleen, less so in liver and kidney, in that order. None of the animals given combined treatment survived the 5-week course of injections. The results show that irradiation accelerated the deposition of amyloid.