Opsonization of Actinobacillus actinomycetemcomitans by LPS-Directed IgG Antibodies in Sera of Juvenile Periodontitis Patients

Periodontitis, commonly known as gum disease, is an inflammatory process that leads to the progressive loss of periodontal ligament cells and alveolar bone that provide support for the teeth. Bacteria resident in dental plaque are considered to be the primary etiologic agents of periodontal disease. The results suggest that Localized juvenile periodontitis (LJP) sera contain immunoglobulin G antibodies that recognize both the core glycolipid and polysaccharide regions of serotype b LPS, although antibodies to the latter predominate. This chapter examines the subclass distribution of IgG antibodies to serotype b lipopolysaccharide (LPS) in sera of these patients. Concentrations of both IgGl and IgG2 antibodies to serotype b LPS were significantly elevated in high-titer LJP sera as compared with low-titer sera. Coating of bacterial surfaces with IgG antibodies can lead to enhanced phagocytosis and killing of many species of bacteria through a process termed opsonization and often requires the presence of complement.