Interactions between granulocytes and platelets with the guinea-pig lung in passive anaphylactic shock. Correlations with PAF-acether-induced lesion.

To compare the bronchopulmonary effects of anaphylactic shock with those of platelet-activating factor (PAF-acether), antigen (ovalbumin) was administered intravenously to passively sensitized guinea-pig. Subsequent lung alterations were assessed histologically. Within 1 min following ovalbumin, bronchial and arterial constrictions were observed, accompanied by platelet thrombi in the pulmonary microcirculation, intravascular leucocyte accumulation with diapedesis, disruption of endothelium and alterations of type II pneumocytes. Free eosinophilic granules were scattered in the bronchial submucosa. One h after the infusion of ovalbumin, platelet aggregates had disappeared, bronchoconstriction was over, and denudation of the bronchial epithelium was observed. These alterations resemble to those induced by intravenous PAF-acether, which led us to compare the effects of inhaled PAF-acether and antigen at bronchoconstrictor concentrations. In both cases, leucocytes were aggregated in the microcirculation within 2 min and persisted 1 h later. Massive infiltration of eosinophils and activation and clumping of alveolar macrophages were also noted. Our findings support the involvement of PAF-acether in acute anaphylaxis in the guinea-pig.