Social interaction and wounding in the genesis of "spontaneous" murine amyloidosis

Seven strains of mice were closely observed during the development of amyloidosis in the absence of experimental manipulation except for alteration in group and cage sizes. Amyloid development was greatest in the strains showing the most evident effects of wounding from fighting activity. In groups fighting extensively, up to a 100% incidence of generalized amyloidosis was reached in submissive mice. Groups of female mice did not fight and only developed amyloidosis in association with infection. The occurrence of amyloidosis correlates with the chronic anemia and splenomegaly long known to attend submissive social standing within groups of male mice. Dominant mice were uniformly spared wounding, anemia, splenomegaly and amyloidosis as were singly caged mice. Amyloidosis appearing in the absence of experimental manipulation is a sequel of social submissiveness and consequent wounds.