Recombinant Bovine Interleukin-1β Amplifies the Effects of Partially PurifiedPasteurella haemolyticaLeukotoxin on Bovine Neutrophils in a β2-Integrin-Dependent Manner

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Abstract
The influx and death of polymorphonuclear leukocytes within the infected lung are hallmarks of bovine pasteurellosis. Recent reports have shown that thePasteurella haemolyticaleukotoxin (LKT) and other RTX toxins bind β2-integrins on target cells. In this study we demonstrate that exposure of bovine neutrophils to recombinant bovine interleukin-1β upregulates β2-integrins (CD11a/CD18), which in turn enhance the binding and amplify the biological effects of partially purified LKT on these cells. LKT binding and cytotoxicity were inhibited by addition of an anti-integrin antibody (CD11a/CD18). These findings help to clarify the early events that occur in bovine pasteurellosis and support the hypothesis that inflammatory mediators might increase the severity of pasteurellosis by causing upregulation of β2-integrins that serve as an LKT receptor on bovine neutrophils.