INACTIVATION OF ENDOTOXIN BY A HUMORAL COMPONENT. VI. TWO SEPARATE SYSTEMS REQUIRED FOR VIABLE AND KILLED SALMONELLA TYPHOSA

Abstract

Alteration of the endotoxin of Salmonella typhosa in its native state on the bacterial surface, after incubation with serum, was studied. Changes in endotoxic behavior were measured by the loss of 2 characteristic attributes; viz., induction of hemorrhagic necrosis in mouse sarcoma 37, and stimulation of specific antibody formation in rabbits. The endotoxic activity of typhoid bacilli killed by heat or by chemical treatment was inactivated by endotoxin-detoxifying component (EDC), the same agent previously shown to affect isolated endotoxin, but was not inactivated by antibody and complement. In contrast, the endotoxic activity of viable bacilli was not affected by EDC but was eliminated by antibody and complement, the recognized bactericidal system of normal serum. Viability was thus the critical factor in determining which of these 2 humoral systems exerted an effect on the endotoxin of typhoid bacilli.