Pulmonary vascular lesions in chickens following intravenous injections of disintegrated cells of Escherichia coli.

Intravenous injections of disintegrated cells of Escherichia coli in chickens were almost constantly followed by extensive lesions in pulmonary arteries; the alterations consisted of mural fibrinoid necrosis, sometimes with slight intramural occurrence of mononuclear inflammatory cells and eosinophils. Massive perivascular accumulations of the same cell types were also very common findings. Affected arteries were frequently occluded by precipitates, predominantly consisting of the injected material, which were rapidly replaced by proliferating endothelial cells, resulting in obliterative lesions, where giant cells sometimes occurred. The conclusion was drawn that the arterial lesions could most adequately be categorized as hypersensitivity angiitis.