The effect of decomplementation on Erysipelothrix rhusiopathiae infection in the mouse.

The intraperitoneal administration of heat-aggregated sheep γ-globulin to mice caused a greater than sixfold decline in serum complement. Decomplementation significantly decreased the mean time to death of mice infected intraperitoneally with , but final mortality in normal and decomplemented groups of mice was similar. When the challenge bacteria were pretreated with fresh mouse serum, decomplementation had no effect and mice survived a lethal challenge of serum-treated organisms. This protective property was removed by heating the mouse serum to 56° for 30 minutes. Decomplementation did not affect the progress of infection in mice with acquired antibody. This suggests that complement protects by opsonization.