Immunoglobulin G subclass response of juvenile periodontitis subjects to principal outer membrane proteins of Actinobacillus actinomycetemcomitans.
The cell envelope of Actinobacillus actinomycetemcomitans includes a number of outer membrane proteins (OMPs) which appear to be important targets for immunoglobulin G (IgG) antibodies in sera from localized juvenile periodontitis (LJP) patients. In this study, we examined the subclass distribution of IgG antibodies reactive to the 16.6- and 29-kDa OMPs of A. actinomycetemcomitans in sera from LJP patients and periodontally healthy individuals. Antibody responses were determined in a quantitative enzyme-linked immunosorbent assay that employed human IgG subclass-restricted monoclonal antibodies. High-titer LJP sera (93% black; geometric mean titer, 32,673) were found to contain significantly elevated levels of IgG1, IgG2, and IgG3 antibodies to the 29-kDa OMP of A. actinomycetemcomitans, compared with those of low-titer LJP sera (mean titer, 1,421) and sera from periodontally healthy, race-matched control subjects. The concentration of IgG2 antibody to this protein was greater than or equal to the corresponding IgG1 concentration in 7 of 14 high-titer sera, although mean IgG1 and IgG2 concentrations were not significantly different. The concentrations of IgG1 and IgG2 antibodies to the 16.6-kDa protein were also significantly elevated in LJP sera, although of considerably lesser magnitude than that observed for the 29-kDa protein. The IgG2 response to the 29-kDa protein could not be attributed to the presence of IgG2 antibodies to lipopolysaccharide contaminants or to Fc-binding activity, nor does this molecule appear to be a glycoprotein. Hence, LJP subjects produce IgG2 antibodies, as well as IgG1 and IgG3 antibodies, directed to at least one of the major OMPs of A. actinomycetemcomitans.
Wilson
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Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo 14214.
Hamilton
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D000293:Adolescent; D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology*; D000907:Antibodies, Bacterial / Q000097:blood*; D000911:Antibodies, Monoclonal / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001667:Binding, Competitive; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007074:Immunoglobulin G / Q000145:classification*; D010518:Periodontitis / Q000276:immunology*
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D007074:Immunoglobulin G