Pulmonary function and histaminemia after polymyxin B inhalation.

Bronchial challenge with polymyxin B caused a significant bronchoconstriction in 85% of atopic asthmatics. In all atopic asthmatics in whom inhalation of polymyxin B elicited bronchoconstriction, a significant, although not always parallel to the grade of bronchoconstriction, increase in histaminemia was observed. If bronchoconstriction was not elicited, the increase in histaminemia did not occur. It constitutes evidence that the bronchoconstricting effect of polymyxin B is exclusively due to degranulation of mast cells and that histamine released in the bronchi can increase the concentration of histamine in the blood.