The role of the spleen on the endotoxin-induced lung injury is not fully understood. Some authors claimed the defensive role of spleen on the endotoxin toxicity, while the others denied it.
The authors studied the ultrastructural effects of endotoxin on the lung in the rats, as well as modification of the changes by splenectomy with or without isolated splenic cell infusion. Some of the infused splenic cells were isolated after
injection
of endotoxin through splenic vein. Animals were sacrificed 1, 4, 8 and 24 hours after single infusion of 0.5mg per 100gm of body weight of E coli endotoxin, in each group.
@ES The results were summarized as follow:
@EN Endotoxin injection induced endothelial injuries from 1 hour after endotoxin injection, characterized by increased pinocytotic vesicles, increased electron density of cytoplasm, irregularity and long process formation on the luminal surface,
detachment and necrosis of endothelial cells. The lumen of the alveolar capillaries were largely distended and filled with sequestered neutrophils, platelets, monocytes and lymphocytes, Interstitial spaces of alveolar septum were infiltrated by
these
cells in later times, and alveolar air spaces showed increased number of macrophages on later time. Both types of alverolar epithelial cells were also injured, detached out and necrotized, which became relatively quiscent after 24 hours.
These changes were more severe in splenectomized animals, particularly the sequestration of neutrophils and lymphocytes on the alveolar capillaries. Infusion of isolated splenic cells to the splenectomized animals could prevent the toxicity of
endotoxin
amplified by splenectomy, in both groups of animals infused splenic cells, whether previous endotoxin exposure was done or not.
The results suggested that spleen exerted defensive role on the endotoxin toxicity by involvement of cellular components through mechanisms not fully understood as yet.
|