Immunodominant antigens of Actinobacillus actinomycetemcomitans serotype b in early‐onset periodontitis patients

Abstract

Previous work with Actinobacillus actinomycetemcomitans strain Y4 (serotype b) indicates that the immunodominant antigen in high-responding patients (top 10%, 80% of which were black) is the serotype-specific antigen. In this study we examined the immunodominant antigens of A. actinomycetemcomitans strain Y4 in both black and white patients having a range of antibody titers. We sought to test the hypothesis that the immunodominant antigen in these subjects was the same antigen found in high responders. Seropositive white early-onset periodontitis (EOP) patients were selected from 99 EOP patients. Black subjects were then selected with comparable antibody titers. Double immunodiffusion and competition assays were used to determine whether reactive antibodies were A. actinomycetemcomitans serotype b-specific or whether the response was to serotype a or c. The immunodominant antigens were then determined for the patients reacting specifically to A. actinomycetemcomitans Y4 using limiting dilution analysis on Western blots. The immunodominant antigen for the A. actinomycetemcomitans Y4-specific patients appeared to be the serotype-specific carbohydrate for most subjects (19/20 or 95%, including: 13/14 black and 6/6 white patients). In conclusion, the immunodominant antigen for A. actinomycetemcomitans Y4 was the serotype-specific carbohydrate regardless of antibody titer for both black and white specifically reactive patients.

Monocyte Differentiation in Localized Juvenile Periodontitis Is Skewed toward the Dendritic Cell Phenotype

“…As noted above, MDDC also produce or facilitate the accumulation of the Th1-associated cytokines that are essential for the production of IgG2 (6,14,21). Much of the IgG2 response is directed against carbohydrates (3,4,36), the very structures that are highly expressed on the surfaces of oral pathogens and initiate the uptake of these organisms by antigen-presenting cells. The IgG2 subclass of antibodies can activate the alternative pathway of complement, and IgG2 is an effective opsonin when it is paired with the H131 allotype of Fc␥RII (33,34).…”

“…These organisms (P. gingivalis and A. actinomycetemcomitans, for example) express a variety of cell surface carbohydrates, and much of the antibody response is directed against these structures (3,4,36). Cell surface oligosaccharides also facilitate the phagocytosis of oral bacteria by antigen-presenting cells, such as macrophages and immature MDDC.…”

DestructivePeriodontitisLesions areDetermined by theNature of theLymphocyticResponse

“…However, different patterns of immunoreactivity with periodontopathic bacteria have been demonstrated for A. actinomycetemcomitans (Califano et al ., 1991(Califano et al ., , 1992Engström et al ., 1993;Ebersole et al ., 1995) and for P. gingivalis (Curtis et al ., 1991;Kurihara et al ., 1991;Polak et al ., 1995). Since these responses are regulated by immunoregulatory genes, it may be that antibody responses are protective in one individual but not in another (Offenbacher, 1996).…”

Regulation of Immunoglobulin G2 Production by Prostaglandin E2and Platelet-Activating Factor

“…Much of this IgG2 antibody is directed against Actinobacillus actinomycetemcomitans serotype b, a putative etiologic agent for EOP, and Porphyromonas gingivalis, which is also associated with EOP (8,20,36,37). The immunodominant antigens of these organisms are the serotype-specific carbohydrates, and, for A. actinomycetemcomitans, the carbohydrate is a high-molecular-weight form of lipopolysaccharide (LPS) (7,8,35,36). Compared to NP subjects, EOP patients frequently have very high titers of IgG2 reactive with the high-molecular-weight A. actinomycetemcomitans LPS, and this antibody is associated with less-severe disease (6).…”