Histopathological lesions produced by P. aeruginosa lipopolysaccharide in rats.

The lipopolysaccharide (LPS) of Pseudomonas aeruginosa is considered to be less toxic than the LPS from the Enterobacteriaceae family. The present study was undertaken to determine the time course of lesions produced in the lungs, spleen, liver, kidneys and bone marrow from 1 to 168 hours following a single (1.5mg) intravenous injection of P. aeruginosa LPS--1R (S-form), and its mutant strains, 557 (R-form) and 605 (more-R-form)--in rats. The lesions consisted of atelectasis, infiltration by polymorphonuclear leukocytes, intraalveolar hemorrhage and perivascular edema of the lung, hyperplasia of the white pulp of the spleen, necrosis of hepatic parenchyma, vacuolization of cells of the adrenal zone fasciculata, and hyperplasia of bone marrow. Immunoperoxidase stain for the R-form and the more-R forms of LPS of P. aeruginosa showed similar distribution kinetics within hepatocytes and Kupffer cells, while the S-form required 24 hours to become evident within hepatocytes. The data show that all 3 LPS preparations are toxic, distributed differently within hepatocytes, as demonstrated by immunoperoxidase stains, and exhibit different time courses and severity of lesions within the affected organs.