Histamine generation by bacteria in sputum of patients with chronic obstructive airway disease

Previous investigations have demonstrated high histamine concentrations in the sputum of patients with chronic obstructive airway disease (COAD). A possible histamine generation by bacteria has been discussed. In the present work, histamine concentrations in native and incubated sputum of patients with COAD were determined. Histamine was assayed fluorimetrically after separation by HPLC. Histamine concentration in native sputum amounted to 10-1140 ng/ml. After 72 h incubation at 37 degrees C 100-20,700 ng/ml histamine was detected. A mean 26-fold increase in histamine content was observed. Heating of the sputum almost completely prevented the rise in histamine concentration during incubation. The same effect was achieved by adding an antibiotic to the sputum before incubation. Histamine content in sputum of patients with COAD decreased considerably after therapy with the antibiotic doxycycline. Histamine formation by bacteria may account considerably for the histamine concentration in sputum of patients with COAD.