Role of pulmonary alveolar macrophage activation in acute lung injury after burns and smoke inhalation.

Bronchoalveolar lavage cells from 42 fire victims and from 18 patients who were smokers attending for diagnostic bronchoscopy (controls) were assessed morphologically and by chemiluminescence. 10 of the victims had inhaled smoke only; 15 had cutaneous burns only; and 17 had combined injury. The combined injury group had significant increases in polymorphonuclear leucocytes and macrophages, especially mature forms, compared with controls. These increases were higher than those expected from the individual injuries. The combined injury group had significantly greater spontaneous chemiluminescence than controls, again greater than that expected by the individual injuries. The chemiluminescence response to stimulation by opsonised bacteria was significantly higher in the combined injury group than in controls, but significantly lower than that in the smoke inhalation only group. The size of the alveolar cellular response to smoke and cutaneous burns suggests that lung damage follows from excess release of inflammatory mediators, exhaustion of the reserve of mature phagocytes and consequent reduced ability to fight bacteria, or both.