title: Role of lipopolysaccharide in induction of Ia expression during infection with gram-negative bacteria.
abstract: Lipopolysaccharide (LPS), a major component of the outer membrane of gram-negative bacteria, is known to be a potent modulator of many host immune functions, including the expression of products of the class II major histocompatibility locus (Ia molecules) by macrophages. LPS-mediated Ia induction is controlled by the lps gene. We sought to determine the role of LPS in the induction of Ia expression during infection with gram-negative bacteria. To address this question, we tested a simple prediction: if LPS is the primary determinant of Ia induction during gram-negative infection, then the Ia response to intraperitoneal injection of these organisms should be under the control of the lps gene. We found that while both LPS-responder and LPS-low-responder mice showed strong Ia responses to injection of either a gram-positive bacterium (Listeria monocytogenes) or concanavalin A, only the LPS-responder mice responded strongly to gram-negative organisms or to LPS alone. We interpret these results as strong evidence for the role of LPS as the primary determinant of Ia induction by gram-negative bacteria.
authors.affiliation: Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322.
authors.forename: N E
authors.initials: NE
authors.lastname: Marshall
authors.forename: H K
authors.initials: HK
authors.lastname: Ziegler
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology; D005260:Female; D006090:Gram-Negative Bacteria / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D010529:Peritoneal Cavity / Q000166:cytology; D012475:Salmonella / Q000276:immunology
chemical_list: D000949:Histocompatibility Antigens Class II; D008070:Lipopolysaccharides