Effect of passive immunization on phagocytosis of blood-borne Escherichia coli in spleen and liver of turkeys.

Clearance of Escherichia coli from blood and localization in tissues were studied by culture and microscopy in nonimmunized and passively immunized turkeys after IV inoculation. In nonimmunized poults, high mortality was associated with persistence of large numbers of E coli in the blood. In immunized poults, rapid clearance of E coli from blood was associated with large numbers of E coli in hepatic sinusoids and fewer bacteria in the spleen. An electron-dense, fibrillogranular coat covered extracellular E coli in immunized poults, but not in nonimmunized poults. Rapid clearance of virulent E coli from blood was markedly enhanced by antibody-dependent phagocytosis in liver.