Heterophile antibodies and tissue injury. 1. Ultrastructure of pulmonary vascular lesions produced by Forssman antiserum in guinea-pigs.

The ultrastructural features of pulmonary vascular lesions were studied in guinea-pigs subjected to lethal Forssman shock. Within moments after an intravenous injection of Forssman antiserum the endothelia of venules and capillaries exhibited a wide range of morphological changes. Relatively mild lesions were characterized by the appearance of focal erosions in the cell membrane, cytoplasmic swelling and vacuolization. Severe lesions were associated with overt necrosis and disintegration of the endothelial lining, leaving the basement membrane in direct communication with the intravascular compartment. Platelets and PMN-leucocytes were consistently found to be adhering to denuded or damaged vascular surfaces and forming thromboembolic obstructions within blood channels. These data support the concept that vascular endothelium is a primary target tissue in Forssman shock. In addition, our findings suggest that platelets and PMN-leucocytes may be pathogenetic determinants in the development of Forssman shock.