title: Minimal concentration of human IgM and IgG antibodies necessary to protect mice from challenges with live O6 Escherichia coli.
abstract: This work evaluated the ability of human anti-lipopolysaccharide O6 IgM and IgG antibodies to protect mice challenged with Escherichia coli serotype O6 : K2ac. Purified IgM-effluent, purified IgG, pools of normal human serum (NHS), or control group were injected into mice 18 h before challenges with O6 E. coli. Interleukin 6 and tumor necrosis factor alpha were quantified in the sera of test and control groups. All mice receiving purified IgM-effluent (66.6 mg L(-1) of anti-lipopolysaccharide O6 IgM antibodies) and NHS survived. Purified IgG (1.1 mg L(-1) of anti-lipopolysaccharide O6 IgG antibodies) protected 87.5% of the animals. The control group showed no protective ability. The minimal concentration of anti-lipopolysaccharide O6 IgM antibodies, able to protect 50% of the animals was 33.3 mg L(-1) of purified IgM-effluent, whereas purified IgG was able to protect 50% of the animals with only 1.1 mg L(-1) of anti-lipopolysaccharide O6 IgG antibodies. Serum from animals pretreated with purified IgM-effluent and purified IgG before challenges with lipopolysaccharide O6 did not have detectable pro-inflammatory cytokines. Hepatocytes of the control group were completely invaded by bacteria, whereas none was found in animals pretreated with purified IgM-effluent and purified IgG. Higher concentrations of anti-lipopolysaccharide O6 IgM antibodies as compared to anti-lipopolysaccharide O6 IgG antibodies were needed to protect mice from challenges with E. coli O6 serotype.
authors.affiliation: Department of Immunology, Institute of Biomedical Sciences, Universidade de São Paulo, Brazil.
authors.forename: Silvia Maria Gomes
authors.initials: SM
authors.lastname: Massironi
authors.forename: Christina
authors.initials: C
authors.lastname: Arslanian
authors.forename: Magda Maria Sales
authors.initials: MM
authors.lastname: Carneiro-Sampaio
authors.forename: Gerlândia Neres
authors.initials: GN
authors.lastname: Pontes
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D016207:Cytokines / Q000097:blood; D004195:Disease Models, Animal; D004926:Escherichia coli / Q000276:immunology* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000276:immunology* / Q000517:prevention & control*; D005260:Female; D022781:Hepatocytes / Q000382:microbiology; D006801:Humans; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology; D008099:Liver / Q000382:microbiology; D008297:Male; D051379:Mice; D019081:O Antigens / Q000276:immunology; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D016207:Cytokines; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D019081:O Antigens