Influence of bronchoalveolar washing supernatants and stimulated lymphocyte supernatants on uptake of Pasteurella haemolytica by cultured bovine alveolar macrophages.

Bovine alveolar macrophages cultured for 12 hours with normal bovine bronchoalveolar washing supernatants (BWS) showed impaired phagocytosis of Pasteurella haemolytica when compared with phagocytosis in control cultures. Such impairment was not observed when another gram-negative bacillus, Yersinia enterocolitica, was used. The BWS from calves inoculated subcutaneously or intrabronchially with P haemolytica inhibited uptake of P haemolytica when BWS were incubated with the bacteria prior to addition to macrophage cultures. However, serum from these calves had pronounced opsonizing activity. Supernatants from stimulated and nonstimulated bovine peripheral blood lymphocyte cultures also inhibited phagocytosis of P haemolytica.