The involvement of polymorphonuclear leukocytes in the pathogenesis of bronchopneumonia in calves. VI. Superoxide dismutase and lipoprotein lipase activities.

The kinetics of superoxide anion production in polymorphonuclear leukocytes of bronchopneumonic calves, as well as superoxide dismutase and lipoprotein lipase activities in the blood plasma of these animals were studied. Granulocytes of bronchopneumonic calves were found to produce 10 times as much O2- radicals as those of healthy animals. Superoxide dismutase and lipoprotein lipase activities were lower in the plasma of bronchopneumonic calves. Escherichia coli endotoxin was found to stimulate superoxide anion production in polymorphonuclear leukocytes in a dose-dependent manner. These facts suggest that an endogenous mediator, probably cachectin or some other monokine(s), plays a role in granulocyte activation during calf bronchopneumonia.