Jpn. J. Infect. Dis., 57, 150-155, 2004
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Original Article
Protective Role of Liposome Incorporated Lipopolysaccharide Antigen of Klebsiella pneumoniae in a Rat Model of Lobar Pneumonia
Sanjay Chhibber*, Sunita Wadhwa and Vanashree Yadav
Department of Microbiology, Panjab University, Chandigarh 160014, India
(Received September 26, 2003. Accepted April 14, 2004)
*Corresponding author: Mailing address: Department of Microbiology, Basic Medical Sciences Building, Panjab University, Chandigarh 160014, India. Tel: +91-172-541770, 534141, Fax: +91-172-541409, E-mail: vanashree_y@yahoo.com
SUMMARY: In a lobar pneumonia model of Klebsiella
pneumoniae, the immunoprotective role of free lipoploysaccharide
(LPS) and liposome-incorporated LPS was studied. An alteration
in the biological activity of the LPS molecule, in terms of its
pyrogenicity and lethal toxicity, was observed on incorporation
in the liposome. Compared at equal doses, liposome-incorporated
LPS was found to be non-pyrogenic and 10 times less toxic than
free LPS. Liposome-incorporated LPS was more effective in providing
protection against K. pneumoniae induced lobar pneumonia
in rats. The immunological mechanism underlying protection revealed
involvement of both nonspecific and specific immune response.
Alveolar macrophage activation was observed after 4 and 14 days
of treatment with the free and liposome-entrapped forms of LPS,
respectively. Specific immunity in terms of plaque-forming cells
was seen with both forms of LPS. Delayed type hypersensitivity
reaction was observed only with liposome-incorporated LPS. It
is concluded that a non-toxic and immunogenic form of K.
pneumoniae LPS can be obtained by incorporation of the native
preparation into liposomes.