Cytochalasin B-induced superoxide production in polycation-treated neutrophils

Oxidative metabolism and release of myeloperoxidase from polymorphonuclear leukocytes obtained from blood sedimentation in a Ficoll-Hypaque gradient

Polymorphonuclear neutrophils (PMN) have an important role in the host defence response to infection. These cells produce large amounts of reactive oxygen species (O(2).(-), H(2)O(2) and ONOO(-)) with microbicidal activity. PMN are commonly isolated from peripheral blood by sedimentation through a gradient of density (Ficoll-Hypaque gradient and dextran), yielding a highly homogeneous cellular population. However, some cellular activation due to membrane perturbation is also expected. We studied how the production of reactive oxygen species and release of myeloperoxidase (MPO) from blood PMN are affected by the use of the Ficoll-Hypaque density gradient. PMN isolated by spontaneous sedimentation and total blood were used for comparisons. Lucigenin- and luminol-enhanced chemiluminescence was used to estimate the production of reactive oxygen from intact cells and shown to be higher for cells isolated by density gradient both in the absence and presence of added stimuli. The release of MPO, estimated by the chemiluminescence of the luminol/H(2)O(2) reaction in the supernatant of PMN incubated in the absence and presence of stimuli and absence and presence of cytochalasin B, was also higher for PMN isolated by a density gradient. In conclusion, it was shown that the PMN isolation procedure affects reactive oxygen species production and MPO release and in some cases may cause a misinterpretation of results.

Effect of antigen challenge on the activation of peripheral blood neutrophils from horses with chronic obstructive pulmonary disease

The effect of antigen challenge on the state of activation of peripheral blood neutrophils from horses with chronic obstructive pulmonary disease (COPD) has been determined by measuring neutrophil superoxide anion formation. Prior to a seven-hour antigen challenge superoxide anion production by neutrophils from asymptomatic horses with COPD and normal horses in response to platelet activating factor (PAF) (with and without cytochalasin B), serum treated zymosan (STZ) and phorbol myristate acetate (PMA) was similar. Agonist-induced superoxide production by neutrophils from symptomatic COPD and normal horses remained unchanged five and 24 hours after antigen challenge. Interestingly, however, superoxide production by neutrophils from symptomatic COPD horses was significantly increased 24 hours after antigen challenge in the control samples for each agonist (basal superoxide production), a five-fold increase being measured in the presence of cytochalasin B. There was a small increase in superoxide production by neutrophils from normal horses but this only reached significance in one set of control samples. The change in activation state of circulating neutrophils during antigen challenge may facilitate the lung neutrophilia and subsequent tissue damage which occur in COPD.