EFFECTS OF PASTEURELLA-HAEMOLYTICA LEUKOTOXIN AND LIPOPOLYSACCHARIDE ON HISTAMINE, PROSTANOID, AND LEUKOTRIENE RELEASE BY BOVINE LUNG PARENCHYMA IN-VITRO

Objective-To identify the effect of Pasteurella haemolytica lipopolysa ccharide (LPS) and leukotoxin (LKT) on spontaneous and calcium ionopho re-induced histamine and inflammatory mediator release from isolated b ovine lung parenchyma. Sample Population-Lungs from 8 healthy cattle. Procedure-Isolated bovine lung parenchyma was incubated in vitro for 2 hours with LKT or LPS, and spontaneous and induced release of inflamm atory mediators was determined. Results-LKT and LPS increased spontane ous release of histamine and leukotriene B-4. In addition, incubation with IFS increased spontaneous release of prostaglandin E-2. Moreover, a differential effect of the 2 toxins on calcium ionophore-induced in flammatory mediator release was observed. LKT specifically primed isol ated lung parenchyma to release leukotriene B-4 and thromboxane B-2 in response to calcium ionophore, whereas LPS did not alter the profile of prostanoids released by bovine lung tissue exposed to calcium ionop hore. Conclusions-Pasteurella haemolytica toxins have a direct effect on bovine lung parenchyma, causing release of inflammatory mediators, which contribute to response to infection. Furthermore, bacterial toxi ns (LKT in this study) may sensitize tissues to the effects of other i rritant stimuli, amplifying the inflammatory response.