Increased PMA-induced chemiluminescence from whole blood of patients with bronchial hyperreactivity

Blood phagocytes from patients with asthma have an increased capacity to produce reactive oxygen metabolites. We studied whether whole blood luminol-dependent chemiluminescence could detect this phenomenon in patients with a normal spirometry but bronchial hyperreactivity as determined with a methacholine bronchial challenge test. Whole blood chemiluminescence, serum eosinophilic cationic protein (ECP), and serum myeloperoxidase (MPO) were determined from 50 patients referred for a methacholine challenge due to prolonged cough and/or dyspnoea. The chemiluminescence results were compared to those from 15 healthy persons. The hyperreactive patients (n = 18) had significantly higher phorbol 12-myristate 13-acetate (PMA)-induced whole blood chemiluminescence values (mean 18.8 mV.min-1; 95% confidence limits (C.L.) 16.3-21.3 mV.min-1) than the normoreactive patients (mean 14.2 mV.min-1; 95% C.L. 13.0-15.5 mV.min-1;) and the healthy controls (mean 12.8 mV.min-1; 95% C.L. 11.7-13.9 mV.min-1). There was no significant difference in PMA-induced chemiluminescence between the normoreactive patients and the controls. The hyperreactive patients had higher serum ECP values than the normoreactive patients, but there was no correlation between whole blood chemiluminescence and serum ECP levels or total eosinophil count. There was no significant difference in monocyte reactive oxygen metabolite production or serum MPO values between the normoreactive and the hyperreactive patients. We suggest that the increased PMA-induced whole blood chemiluminescence in bronchial hyperreactivity is due mainly to an activation of neutrophils, and that the assay might be useful as a systemic inflammatory marker in patients with pulmonary inflammatory processes resulting in bronchial hyperreactivity.