[Effect of liposome-encapsulated recombinant human superoxide dismutase (liposome-r-h-SOD) on the lung injury induced by Forssman antiserum in guinea pigs].

We investigated the effect of liposome-r-h-SOD on the lung injury induced by Forssman antiserum in guinea pigs. Intravenous injection of Forssman antiserum produced a biphasic increase in pulmonary resistance in guinea pigs. Liposome-r-h-SOD blocked this biphasic increase in a dose-dependent manner. Exudate and hemorrhage in the alveolar spaces and connective tissues were blocked by liposome-r-h-SOD. Liposome-r-h-SOD was more effective when it was injected 30 min prior to challenge than 5 min prior to challenge. On the other hand, free r-h-SOD or a mixture of free r-h-SOD and empty liposome did not block the lung injury. SOD activity in porcine endothelial cells cultured with liposome-r-h-SOD increased in a dose-dependent and time-dependent manner, while it did not increase with free r-h-SOD. Exogenous SOD was detected by immunoperoxidase staining in endothelial cells of arterioles and capillaries and in alveolar epithelial cells of the lung of guinea pigs injected with liposome-r-h-SOD. These findings suggest that superoxide radical may take part in the lung injury induced by Forssman antiserum. Liposome-r-h-SOD, which adheres to and/or is endocytosed by endothelial cells, may protect the lung from oxygen radicals.