INTERACTION BETWEEN PASTEURELLA-HAEMOLYTICA AND BOVINE ALVEOLAR MACROPHAGES - CYTO-TOXIC EFFECT ON MACROPHAGES AND IMPAIRED PHAGOCYTOSIS

Abstract

Cultured bovine alveolar macrophages phagocytosed formalized 125I-labeled P. haemolytica organisms poorly when compared with uptake of an identical number of radiolabeled Yersinia enterocolitica organisms. Presence of immune serum enhanced uptake of P. haemolytica, yet at high bacteria-to-macrophage ratios, a significant positive correlation existed between uptake and loss of cells from coverslips. This phenomenon was not observed with Y. enterocolitica. While culture supernatant from P. haemolytica impaired phagocytosis or was cytotoxic to cultured macrophages, supernatant from Y. enterocolitica did not show this effect. The observation of an apparent detrimental effect on bovine alveolar macrophages after uptake of P. hemolytica may be used to explain events occurring in pneumonic pasteurellosis in cattle and may help development of immunization techniques.