Cytotoxin of Pasteurella haemolytica acting on bovine leukocytes

The toxicity of Pasteurella haemolytica culture supernatant for bovine and porcine cells was evaluated by 51Cr release. Sterile bacterial culture supernatant was toxic for bovine pulmonary lavage cells, peripheral blood lymphocytes and neutrophils, and cultured peripheral blood mononuclear cells, resulting in marked 51Cr release. Only slight release was induced from cultured Madin-Darby bovine kidney cells, porcine pulmonary lavage cells, peripheral blood mononuclear cells, lymphocytes, or neutrophils. No release was detected with primary bovine spleen cell cultures, bovine erythrocytes, or porcine erythrocytes. The demonstrated specificity of this cytotoxin for bovine leukocytic cells may be important in the pathogenesis of bovine pneumonic pasteurellosis.