The influence of TNFalpha and IL-8 on secretory action of neutrophils isolated from heifers in the course of bovine respiratory disease.

The goal of this study was to give insight into the lesser known action of neutrophils in the course of bovine respiratory disease (BRD). Neutrophils are principally involved in resistance to infection but under certain conditions these cells participate in lung injury. TNFalpha and IL-8, primary cytokines which play an essential role in neutrophil activation during the inflammatory process, may lead not only to host defence reaction but also to destructive responses. Neutrophil constituents, such as elastase, myeloperoxidase (MPO), alkaline phosphatase (ALKP) and superoxide among others, contribute to tissue destruction. Also, 5-oxo-eicosatetraenoic acid (5-oxo-ETE), the potent activator of neutrophil chemotaxis and degranulation, can cause lung injury. This study revealed that neutrophils under the influence of TNFalpha exacerbated the release of elastase, MPO, ALKP and superoxide. IL-8, in turn, triggered those neutrophils which were isolated from heifers suffering from BRD, and released elastase, ALKP and 5-oxo-ETE, but not MPO or superoxide (O2(-)). The most pronounced degranulative response was observed in the acute form of BRD and a lesser response was seen in the chronic form. The secretory action of neutrophils varied not only depending on the form and phase of the disease but it also diminished successively during recovery.