Reactive antigens of the periodontopathic bacterium. Actinobacillus actinomycetemcomitans.
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Actinobacillus Infections↗
Biomedical subjects
R C Page
Publications and source records attributed to R C Page.
Smooth muscle and epithelial cells express specific binding sites for the C1q component of complement.
In injury and inflammation, interactions of complement C1q with C1q receptors may provide attachment sites for cell localization and tissue regeneration. Cultured smooth muscle cells (58%), epithelial cells (26%), and endothelial cells (25%) attach to C1q-coated surfaces, while only 6% of cultured B cells (Raji) attach. Endothelial and Raji cells express C1q receptors, but C1q receptors (C1qR) on smooth muscle cells and epithelial cells have not previously been demonstrated. Evidence is provided that smooth muscle cells express an average of 1.5 x 10(6) C1qR/cell (K alpha = 10(8) M-1) and that epithelial cells express an average of 0.7 x 10(6) C1qR/cell (K alpha = 1.4 x 10(8) M-1). Binding properties of C1qR, and immunoreactivity to anti-C1qR antibodies, are characterized. The antibodies specifically recognize a 67-kDa component of smooth muscle cell lysates and inhibit cell attachment to C1q substrates. We conclude that distribution of C1qR may be ubiquitous; binding properties, size, and antigenicity of various C1qR may be related, but adhesive function may be tissue specific.
Animals↗
Isolation of human tumor cells that produce cementum proteins in culture.
We have cultured cells from explants of a human cementum tumor. The cells obtained were multipolar, they formed network-like structures and they were alkaline-phosphatase positive. Immunostaining and Western blots using specific antibodies revealed that these cells produced bone sialoprotein and collagen types I and V, and they also mineralized in vitro. Conditioned medium was mitogenic to fibroblasts and mitogens present were separated by heparin-affinity chromatography. Based on affinity to heparin and antibody-inhibition studies, the heparin fractions were shown to contain cementum-derived growth factor, platelet-derived growth factor and fibroblast growth factors. The cementum tumor cells, but not gingival fibroblasts, were stained positively by an antibody to cementum-derived attachment protein. The attachment protein was separated by immunoaffinity chromatography, and Western blots revealed that the preparation contained 56-kDa and 43-kDa proteins as major bands. Cells pulse-labeled with radioactive amino acids contained a 43-kDa protein as the major component; however, this protein was absent after a cold chase in the presence of cycloheximide, but 56-kDa, 39-kDa and 26-kDa species became prominent. These data indicated that the 56-kDa cementum attachment protein is derived from a 43-kDa precursor. Our data show that the cells cultured from the cementum tumor represent cementum cells capable of synthesizing and secreting cementum proteins in culture.
Alkaline Phosphatase↗
Isolation and partial characterization of a growth factor from human cementum.
Cementum is the mineralized interface through which collagen fibers of periodontal connective tissues are anchored onto the tooth surface. We have isolated and partially characterized a mitogenic factor from human cementum which has properties different from other growth factors. Cementum was harvested from healthy human teeth, extracted in 1.0 M CH3COOH and mitogenic activities were fractionated by heparin-affinity chromatography. Proteins eluted by 0.4-0.6 M NaCl, which contained most of the cementum mitogenic activity, were precipitated by trichloroacetic acid and resolved by HPLC through ion-exchange and reverse-phase columns. NaDodSO4-polyacrylamide gel electrophoresis revealed that the purified preparation contained a M(r) 23,000 protein and this protein was associated with mitogenic activity. The purified cementum-derived growth factor (CGF) was active alone, but at suboptimal concentrations its activity was potentiated by small quantities of plasma-derived serum and epidermal growth factor (EGF). The activity was resistant to heat, but it was destroyed by trypsin digestion. Reduction and alkylation destroyed the mitogenic activity, however electrophoretic mobility was not affected. Binding of EGF to fibroblast membranes was not affected by the CGF and assays to detect platelet-derived growth factor were negative. These characteristics indicated that CGF is a distinct molecular species. Our data show that cementum contains several mitogenic factors and that CGF is the major cementum mitogen.
Cell Division↗
Production of a monoclonal antibody to an attachment protein derived from human cementum.
Cementum is the mineralized structure that covers the surface of the roots of teeth; it serves as the attachment site for collagen fibers of adjacent soft connective tissues. Very little is known about how cementum formation is regulated or how it affects other periodontal structures. We have raised a monoclonal antibody that may aid in studies to determine the biology and function of cementum. Mice were immunized with a 55-kDa attachment protein partially purified from human cementum and a monoclonal antibody, H166, was produced. Incubation of tissue sections with this antibody and fluorescein isothiocyanate-conjugated secondary antibody revealed that it immunostains cementum but not dentin, gingiva, or periodontal ligament. Alveolar bone did not bind the antibody, although a few paravascular cells were positive. Long bones, kidney, liver, skin, and several other tissues were negative. Protein fractions separated from cementum extracts by binding to immobilized H166 column contained 55-, 49-, 39-, 29- to 31-, and 23- to 26-kDa components that cross-reacted with the antibody in Western blots; these components were previously shown to be derived from a common precursor. We conclude that the antibody recognizes a group of proteins related to 55-kDa attachment protein in cementum. Our data show that the antibody could serve as a marker for cementum.
Animals↗
Can life-styles of subjects with impaired glucose tolerance be changed? A feasibility study.
Thirty-one subjects with impaired glucose tolerance were randomly allocated to a group receiving advice to improve their diet and physical activity levels over 6 months (n = 23) or to a control group (n = 8). At 6 months, 18 of the 23 subjects receiving 'healthy living' advice were re-examined (five subjects had withdrawn). Fourteen of the 18 subjects showed an alteration in diet or an increase in exercise. The 18 subjects re-evaluated showed a reduction in systolic blood pressure (118 +/- 15 vs 124 +/- 15 mmHg, p less than 0.05) and decrease in total plasma cholesterol (4.5 +/- 1 vs 5.2 +/- 1 mmol l-1, p less than 0.01) and LDL-cholesterol levels (2.8 +/- 0.9 vs 3.2 +/- 0.9 mmol l-1, p less than 0.05). Plasma glucose levels were unchanged. One subject withdrew from the control group. At 6 months, the seven control subjects examined showed no significant change in metabolic parameters, with little measurable change in diet or exercise. At 2 years, 17 of the 23 'healthy living' subjects were reassessed. Nine of the subjects had continued to exercise or maintained a decreased weight compared to baseline. Fasting plasma glucose levels had increased (6.0 +/- 1.2 vs 5.5 +/- 0.6 mmol l-1, p less than 0.05), with the only continued improvement being a reduced LDL level (2.8 +/- 0.7 vs 3.1 +/- 0.9 mmol l-1, p less than 0.05). At 2 years, a similar proportion of the control group were taking regular exercise compared with the 'healthy living' group.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Diagnostic characteristics of crevicular fluid aspartate aminotransferase (AST) levels associated with periodontal disease activity.
During a 2-year period pocket depth, probing attachment level, gingival index, and crevicular fluid aspartate aminotransferase (AST) levels were monitored in 25 previously treated periodontitis patients. Probing attachment level change was used retrospectively to identify sites where active periodontal destruction had occurred. The ability of crevicular fluid AST activities at 600, 800, 1000, and 1200 microIU levels to recognize active disease was investigated. Probing attachment level changes observed support the concept that the pattern of periodontal disease activity is episodic and infrequent. A loss of greater than or equal to 2 mm was found at 11% of all studied sites, whereas a gain of greater than or equal to 2 mm was noticed for 15% of sites. 2 subjects had 3 teeth that lost greater than or equal to 2 mm of attachment, whereas 15 subjects demonstrated no teeth with disease activity. The remaining 8 subjects had 1 or 2 sites that lost greater than or equal to 2 mm of attachment. Bayes's theorem and ROC curves were used to exemplify the sensitivity and the specificity of AST assessments. The AST 800 microIU demonstrated a sensitivity of 0.93 and specificity 0.68 and an odds ratio of 15.4 for attachment loss greater than or equal to 2 mm. Under the conditional probability of either 50%, 25% or 10% active disease prevalence, AST 800 microIU has a predictability of 73%, 50% and 24% respectively.
Aspartate Aminotransferases↗
Design issues specific to studies of periodontitis.
Guidelines for clinical trials demonstrating equivalence or superiority for treatments for periodontitis are badly needed because of the great variety of drugs, agents, and devices now being developed. This paper focuses on three design issues. These are primary outcome variables and their measurement, disease-active vs disease-inactive sites and patients, and study duration. Determinants for selection of outcome variables include the biologic events to be observed, changes that are specific for periodontitis, and methods chosen to detect those changes. The primary outcome variables specific for periodontitis and appropriate for use in clinical trials are periodontal attachment level and alveolar bone status. Improved methods for measurement of both with excellent accuracy and reproducibility are now becoming available. Studies performed on untreated patients over the past decade demonstrate clearly that disease-active and disease-inactive pockets exist, at any given point in time most are inactive, disease progression is episodic and in most patients infrequent, and a rather small portion of the population--possibly around 5%--are unusually susceptible to rapid disease progression. These observations need to be taken into account in enrolling subjects into periodontitis clinical trials. Conducting a prestudy to identify actively diseased sites and susceptible subjects, or screening to enrich the proportion of active sites, is recommended. Determination of study duration is a very complex issue. It is related to the length of time required for maximal change and stabilization to occur in the biological events to be observed, the outcome variable(s) used to detect change, and the nature of the therapeutic interventions to be studied. No single duration is applicable to all periodontitis clinical trials. Large gaps in our knowledge about the design of periodontitis trials still exist, and additional research is needed.
Alveolar Bone Loss↗
Platelet-derived growth factor reduces the inhibitory effects of lipopolysaccharide on gingival fibroblast proliferation.
Lipopolysaccharide from a variety of bacterial sources is known to inhibit gingival fibroblast proliferation and synthetic activity and has been implicated in the pathogenesis of periodontal inflammation. However, it may be involved not only in pathogenesis but also be responsible for delayed wound healing following periodontal therapy. The aim of this investigation was to determine whether the inhibitory effect of LPS on gingival fibroblast proliferation could be reversed by growth factors. Human gingival fibroblasts were cultured in the presence of varying concentrations of platelet-derived growth factor (PDGF) or Salmonella enteritidis LPS to determine the optimal concentrations for stimulation and inhibition of proliferation respectively. The effect of PDGF on LPS inhibition of fibroblast proliferation was studied by combining PDGF and LPS together at the outset of the experimental period or adding PDGF to cells which had been previously primed with LPS. Cell proliferation was monitored by incorporation of 3H-thymidine into precipitable DNA. The results indicated that maximal inhibition of fibroblast proliferation was obtained with 50 micrograms/ml LPS and maximal stimulation of proliferation with 5 ng/ml PDGF. PDGF was found to restore the proliferative activity of the cells exposed to LPS to approximately 60% of their control counterparts. A similar value was obtained for cultures exposed to PDGF after an extended priming period of LPS exposure. Subtle differences were noted in the time taken for cells to complete their cell cycle in the various culture conditions and this may reflect variations in subpopulations of cells in their response to various mitogenic stimuli. Overall the results indicate that PDGF has the capacity to significantly negate and reverse the inhibitory effects of LPS on human gingival fibroblast proliferation.
Cell Cycle↗
Serum immunoglobulin G antibody to Porphyromonas gingivalis in rapidly progressive periodontitis: titer, avidity, and subclass distribution.
Porphyromonas gingivalis is a suspected pathogen in rapidly progressive periodontitis (RPP). We have determined the anti-P. gingivalis serum immunoglobulin G (IgG) isotype response and avidity and the subclass titer distributions for 30 RPP patients and 30 age-, sex-, and race-matched healthy subjects by using enzyme-linked immunosorbent assay technology. Patients and control subjects were classified as seropositive if their total IgG response to P. gingivalis was twofold or more than the median response in healthy subjects. The predominant antibody responses for both patients and healthy subjects were IgG2 and IgG3, with a subclass order of IgG2 greater than IgG3 greater than IgG1 greater than IgG4. The avidity of the IgG response was highest for the seropositive healthy subjects and was no different between seronegative and seropositive RPP patients. The subclass antibody responses did not depend on gender, and there were no correlations between titer, avidity, or subclass with disease severity in the RPP patients as measured by pocket depth or bone loss on dental X rays. The seronegative RPP patients exhibited antibody responses that were greater than the responses of seronegative healthy subjects for all four subclasses, while the seropositive RPP patients had higher IgG1 and IgG4 levels than seropositive healthy subjects. These findings are consistent with the hypothesis that both carbohydrate and protein antigens are important in the IgG response to P. gingivalis. The relative predominance of IgG2, a subclass which lacks strong complement fixation and opsonic properties, and the low avidity of patient anti-P. gingivalis IgG antibodies suggest that humoral responsiveness to infection with P. gingivalis may be ineffective in clearing this organism.
Adolescent↗
Host response tests for diagnosing periodontal diseases.
Extensive data collected over the past decade demonstrate clearly that disease-active and disease-inactive periodontal pockets exist, disease progression is infrequent and episodic, and most progression occurs in a small proportion of highly susceptible individuals. Furthermore, traditionally used diagnostic procedures do not identify susceptible individuals nor distinguish between disease-active and disease-inactive periodontal sites. New diagnostic tests based on host response factors that will aid in resolving these problems appear to be possible. Sources of material for use in such tests include gingival crevicular fluid (GCF), blood cells, and blood serum. Of these, components in GCF are most promising, at least in the immediate future. Although more than 40 GCF components have been studied, efforts that attempt to relate the presence and amount of a given component to an independent measure of active disease are very few in number. As a consequence, we do not yet know the potential for most GCF components as the basis of diagnostic tests. Those components that have been documented to associate with active disease as measured by attachment loss of 2 mm or greater include alkaline phosphatase, beta-glucuronidase, prostaglandin-E2, aspartate aminotransferase, and IgG4 antibody subclass. Even in these cases, the data base is small and additional clinical studies are needed to document claims. At the present time, tests based on beta-glucuronidase, nonspecific neutral proteases, and aspartate aminotransferase are being commercialized. One test has received FDA approval. Tests based on blood cells have limited application for patients with adult periodontitis, but are useful for patients with early-onset forms of periodontitis. An abnormality in the leukocyte adherence molecules on the surfaces of neutrophils is diagnostic for generalized prepubertal periodontitis, and defects in chemotactic receptor numbers and in a surface molecule designated as GP110 are found on the neutrophils of most but not all localized juvenile periodontitis patients. Recent data indicate that enhanced unstimulated or stimulated release of PGE2 and Interleukin-1 by peripheral blood monocytes may be an indicator of susceptibility to severe periodontitis. Assessment of the humoral immune response as reflected by serum antibodies to antigens of periodontopathic bacteria shows little promise as the basis for tests diagnostic of site-specific disease activity. However, the capacity of an individual to mount an IgG2 subclass response to carbohydrate antigens may have potential as an indicator of disease susceptibility.
Gingival Crevicular Fluid↗
Modulation of proteoglycan metabolism by human fibroblasts maintained in an endogenous three-dimensional matrix.
This report describes synthesis and degradation of proteoglycans by human gingival fibroblasts growing in an endogenous three-dimensional matrix. Cells grown in the matrix cultures demonstrated a high rate of proteoglycan synthesis, varying between 2 and 4 times that of cells maintained in monolayer cultures. In addition, the relative amount deposited into the cell layer was increased in the matrix cultures, constituting 70% to 90% of the synthesized material during the first 24 h. Comparable levels for the monolayer cultures were 30% to 60%. The majority of the 35S-sulfate-labeled material in both matrix (80%) and monolayer (62%) cultures was susceptible to chondroitin ABC-lyase digestion. The major product was a low Mr (120,000) proteoglycan which could be immunoprecipitated by an antibody against PGII (decorin). In addition, the cells synthesized two chondroitin ABC-lyase-sensitive proteoglycans, one with Mr greater than 400,000, one with an apparent Mr of 250,000, as well as two heparan sulfate proteoglycans with Mr greater than 250,000. The low Mr dermatan sulfate, decorin, was also the major component deposited in the three-dimensional matrix, constituting about 60% of the total sulfate incorporation. In contrast, fibroblasts in monolayer cultures deposited only a small amount (13%) of decorin (PGII) in the cell layer, and the major proteoglycan in this compartment was heparin sulfate. The rate of release of the newly deposited proteoglycans was the same in the two culture conditions, although material released from the three-dimensional matrix cultures contained small Mr components indicating a higher degree of degradation. These studies show differences in proteoglycan metabolism by gingival fibroblasts grown in an endogenous matrix and in monolayer cultures.(ABSTRACT TRUNCATED AT 250 WORDS)
Cells, Cultured↗
Isolation and partial characterization of mitogenic factors from cementum.
Cementum is the mineralized structure through which soft connective tissues are attached to the teeth. It is a unique calcified tissue characterized by a low metabolic turnover, lack of blood supply, and presence of very few cells. However, it contains substances that influence the biological activities of fibroblasts of adjacent soft tissues. We have partially characterized cementum proteins that have mitogenic activity toward fibroblasts. Cementum was harvested from bovine teeth, and mitogenic factors were extracted in 0.5 M CH3COOH. Heparin-Sepharose chromatography separated the mitogenic activity into a major and a minor fraction eluted by 0.5 and 2.0 M NaCl, respectively. The distribution of cementum mitogens in heparin-Sepharose fractions was different from that of alveolar bone and other bones. The cementum mitogenic factor eluting with 2.0 M NaCl from a heparin-Sepharose column was shown to be basic fibroblast growth factor (bFGF) on the basis of inhibition by anti-bFGF antibody and Western blots. The 0.5 M NaCl fraction was purified by HPLC with use of a combination of a DEAE-3W column followed by TSK-250 and C18 columns. NaDodSO4-polyacrylamide gel electrophoresis revealed that the purified fraction contained two protein bands with Mr 22,000 and 19,000, and mitogenic activity was associated with the Mr 22,000 species. The activity of this mitogen, designated as CGF, was potentiated by small quantities of plasma-derived serum or epidermal growth factor. It was heat resistant, but was destroyed by reduction. Assays of CGF preparations revealed that they contained no detectable platelet-derived growth factor.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Interleukin 1 beta induces rapid phosphorylation and redistribution of talin: a possible mechanism for modulation of fibroblast focal adhesion.
The majority of interleukin 1 (IL-1) receptors in human fibroblasts has been shown to be localized at focal adhesions. This study describes rapid alterations caused by IL-1 beta/IL-1-receptor interaction at these sites. Fibroblast monolayers, incubated with IL-1 beta and prepared for electron microscopy, showed successive loss of cell-substratum contact and fewer and less-pronounced processes. Immunocytochemistry revealed loss and redistribution of the talin staining initially observed after 5-15 min of IL-1 beta incubation. Similarly, the cytoskeleton showed a decrease in staining and a disorganization starting from 15 to 30 min after IL-1 addition, whereas extracellular fibronectin appeared largely unaffected. Prelabeling with [32P]phosphate showed a 2- to 3-fold increase in the level of talin phosphorylation, peaking at 15 min. Phospho amino acid analyses revealed a higher level of serine and threonine phosphorylation. The data suggest that the action of IL-1 beta on fibroblasts may be partially mediated by direct phosphorylation of talin via activation of a protein serine/threonine kinase, leading to changes in transmembrane linkage proteins and the cytoskeleton. Such alterations at focal adhesions may provide a mechanism by which IL-1 can rapidly modulate cell-matrix interactions during inflammation and wound healing.
Cell Adhesion↗
Non-linkage of the islet amyloid polypeptide gene with type 2 (non-insulin-dependent) diabetes mellitus.
Type 2 (non-insulin-dependent) diabetes is associated with the deposition of islet amyloid. The major formative peptide, islet amyloid polypeptide, has recently been characterised and an abnormality of the structure or expression of this gene is a possible candidate for the inherited component of Type 2 diabetes. A restriction fragment length polymorphism of the gene has been identified with Pvu II. To study the relationship between the islet amyloid polypeptide gene and Type 2 diabetes, two distinct genetic approaches have been undertaken. Firstly, non-linkage has been demonstrated in four pedigrees, with four normoglycaemic first degree relatives having an allele associated with diabetes in other family members, and one affected relative not having the putatively associated allele. The LOD score taking age-related penetrance into account was -1.68, making linkage unlikely (p = 0.02). Secondly, in a population-based restriction fragment length polymorphism survey, no linkage disequilibrium of the alleles was found between a population of unrelated Caucasian subjects with Type 2 diabetes and a normal population. A mutation in or near the islet amyloid polypeptide gene is thus unlikely to be a common cause of Type 2 diabetes.
Amyloid↗
The role of inflammatory mediators in the pathogenesis of periodontal disease.
The role of bacteria in the initiation of periodontitis is well-documented and the end result, destruction of the alveolar bone and periodontal connective tissue, is readily observed; but the events occurring between these two points in time remain obscure and are the focus of this paper. Bacteria induce tissue destruction indirectly by activating host defense cells, which in turn produce and release mediators that stimulate the effectors of connective tissue breakdown. Components of microbial plaque have the capacity to induce the initial infiltrate of inflammatory cells including lymphocytes, macrophages, and PMNs. Microbial components, especially lipopolysaccharide (LPS), have the capacity to activate macrophages to synthesize and secrete a wide array of molecules including the cytokines interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-alpha), prostaglandins, especially PGE2, and hydrolytic enzymes. Likewise, bacterial substances activate T lymphocytes and they produce IL-1 and lymphotoxin (LT), a molecule having properties very similar to TNF-alpha. These cytokines manifest potent proinflammatory and catabolic activities, and play key roles in periodontal tissue breakdown. They induce fibroblasts and macrophages to produce neutral metalloproteinases such as procollagenase and prostromelysin, the serine proteinase urokinase-type plasminogen activator (u-PA), tissue inhibitor of metalloproteinase (TIMP), and prostaglandins, u-PA converts plasminogen into plasmin, which can activate neutral metalloproteinase proenzymes, and these enzymes degrade the extracellular matrix components. TIMP inactivates the active enzymes and thereby blocks further tissue degradation. Several amplification and suppression mechanisms are involved in the process. While LPS activates macrophages to produce IL-1, IL-1 is autostimulatory and can therefore amplify and perpetuate its own production. Interferon-gamma (INF-gamma) suppresses autostimulation, but it enhances LPS-induced IL-1 production. PGE2 exerts a control over the whole process by suppressing production of both IL-1 and TNF-alpha. Furthermore, the activated cells produce an IL-1 receptor antagonist that binds to the IL-1 receptor but does not induce the biologic consequences of IL-1 binding. Other cytokines such as transforming growth factor-beta (TGF-beta) suppress production of metalloproteinases and u-PA. Thus the progression and extent of tissue degradation is likely to be determined in major part by relative concentrations and half-life of IL-1, TNF-alpha, and related cytokines, competing molecules such as the IL-1 receptor antagonist, and suppressive molecules such as TGF-beta and PGE2. These molecules control levels of latent and active metalloproteinase and u-PA, and the availability and concentration of TIMP determines the extent and duration of degradative activity.
Alveolar Bone Loss↗
The immunodominant outer membrane antigen of Actinobacillus actinomycetemcomitans is located in the serotype-specific high-molecular-mass carbohydrate moiety of lipopolysaccharide.
Most patients with juvenile periodontitis manifest serum antibodies, sometimes at very high titers, to antigens of Actinobacillus actinomycetemcomitans, but the antigens inducing the immune response have been only partly characterized. We separated A. actinomycetemcomitans serotype b cells into protein, lipopolysaccharide (LPS), and soluble polysaccharide fractions and characterized them. Coomassie blue- and silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels were used to detect protein and LPS components, and gas-liquid chromatography was used to determine their carbohydrate and fatty acid composition. Western blots, dot blots, and enzyme-linked immunosorbent assay inhibition with high-titer sera from juvenile periodontitis patients revealed which components were highest in antibody binding activity. These results showed that the major portion of the immunoglobulin G binding activity resides in the purified mannan-free LPS, with lesser amounts in the total protein fraction. Using Sephacryl S-300 chromatography, we separated LPS into high-molecular-mass components with high carbohydrate contents by gas-liquid chromatography and a low-molecular-mass component consisting mainly of lipid A and the inner core sugar heptulose. The results of quantitative dot blot assays and enzyme-linked immunosorbent assay inhibition show that the serotype-specific antibody binding activity is highly concentrated in the high-molecular-mass carbohydrate-rich LPS fraction and is almost completely absent in the low-molecular-weight lipid-rich fraction. Our observations contrast with previous reports that the predominant serotype antigen of A. actinomycetemcomitans resides in a mannan-rich polysaccharide isolated from spent culture medium. These observations support the conclusion that the immunodominant antigen of the outer membrane is the O antigen of the LPS.
Actinobacillus↗
Antigens of Actinobacillus actinomycetemcomitans recognized by patients with juvenile periodontitis and periodontally normal subjects.
Most juvenile periodontitis patients respond to infection by Actinobacillus actinomycetemcomitans by producing serum antibodies. Specific antigens inducing the humoral immune response have not been identified, nor has the role of the resulting antibodies in disease progression been determined. Adsorbed and unadsorbed sera from juvenile periodontitis patients and normal subjects were analyzed by enzyme-linked immunosorbent assay and Western blots (immunoblots), using digested and undigested bacterial sonicates and French pressure cell fractions to determine the biochemical class, cross-reactivity, and cellular location of the antigens in different A. actinomycetemcomitans serotypes. Antigens detected by using high-titer sera included the following: (i) serotype-specific nonprotein material located on the cell surface, (ii) soluble-fraction proteins showing highly variable antibody binding, (iii) cross-reactive proteins, and (iv) a protein present in soluble and cell wall fractions and immunopositive for all sera tested. In addition, one apparently nonprotein component that was enriched in the cell wall fraction was observed. Sera with high immunoglobulin G titers to one, two, three, or none of the three A. actinomycetemcomitans serotypes were observed. There was a high degree of variation from one patient to another in the humoral immune response to serotype-specific and cross-reactive antigens. As demonstrated by whole-cell adsorption experiments, the serotype-specific surface antigen accounted for approximately 72 to 90% of the total antibody-binding activity for sera with titers greater than 100-fold above background, while cross-reactive antigen accounted for less than 28%. Antibody binding the whole-cell sonicate for high-titer sera was inhibited 90% by lipopolysaccharide from the same serotype, strongly suggesting that lipopolysaccharide is the immunodominant antigen class.
Actinobacillus↗