Airway macrophages. The importance of the fixation method.

Two methods of fixation, intravascular perfusion and intratracheal instillation, were compared with regard to the number, distribution, and appearance of airway and alveolar macrophages. With instillation of fixative, the number of airway macrophages present was reduced to only 32.6% of that seen after intravascular perfusion. Macrophages may have important physiologic and pathologic roles in the airways. The method of fixation is crucial for preservation of their numbers and location.