PRODUCTION OF FREE OXYGEN RADICALS BY PHAGOCYTES FROM RESPIRATORY-TRACT LAVAGED AS WELL AS FROM PERIPHERAL-BLOOD OF HORSES WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE (COPD) IN COMPARISON TO HEALTHY ANIMALS

The phagocytic activity of leukocytes from the peripheral blood as well as from the equine respiratory tract was determined by means of the ''Nylon Column Dye Test'' (NCD-Test), a modification of the Nitroblue Tetrazolium Test (NBT-Test). The investigations were carried out using 24 horses suffering from COPD in comparison to 16 healthy animals. The activity was investigated before and after stimulation with Escherichia coli lipopolysaccharide (LPS) in cells from whole blood and in a cell suspension obtained from tracheobronchial lavage. The mean activity of phagocytic cells as measured by the NBT-reduction in the blood was similar in both healthy horses and those suffering from COPD. In both groups, LPS stimulation increased NBT reduction but in COPD horses the increase was significantly less. The activity of phagocytes from the tracheobronchial tree of COPD horses was 10-fold grater than that of blood phagocytes but there was no significant response to LPS-stimulation. The increased production of reactive oxygen species connected with migration of leukocytes into the lumen of airways and their very high phagocytic activity may be an important factor in the pathogenesis of COPD in horses.