Relationship between gingival crevicular fluid and serum antibody titers in young adults with generalized and localized periodontitis

Crevicular IgG antibodies and recovery of locally implanted Streptococcus mutans in humans

This study was undertaken with the aim of examining the effect of highly different IgG antibody activities in gingival crevicular fluid (GCF) on the elimination of a streptomycin-resistant strain of Streptococcus mutans (S. mutans) topically implanted on the tooth. Two groups of people were selected for the study, one with high and one with low specific IgG antibody activity (IgG antibody activity against S. mutans) in GCF. During an experimental period of 15 d the specific IgG antibody activity in GCF in the same individual stayed on a relatively constant level. Between individuals, however, the specific IgG antibody activity varied considerably. The number of indigenous mutans streptococci and the number of implanted bacteria on the same tooth surface were strongly correlated. The implanted S. mutans strain was rapidly eliminated in all subjects. No difference in the elimination of the implanted strain of S. mutans could be demonstrated between the groups of high and low specific IgG antibody activity.

Immunologic mechanisms of pathogenesis in periodontal diseases: an assessment

Principal lines of evidence that immune reactions are central to the pathogenesis of periodontitis are reviewed. Necessary components of immunologic reactions are present in gingiva in the periodontal diseases. Differences between healthy and periodontitis patients with respect to some measures of immune function further indicate that immune reactions do occur in the gingiva during periodontitis. They are probably responsible for at least some of the destruction of connective tissue and bone that occurs. Classical antibody-mediated hypersensitivity reactions probably do not provide the reasons. Mechanisms are more likely to be found in the pro-inflammatory and tissue-degrading effects of cytokines released in host-protective, antigen-specific and polyclonal responses to oral bacterial constituents or products. Some evidence suggests that limitation of clinical destruction in localized early onset periodontitis (JP) may in part be a function of a protective antibody response which develops after an initial rapidly progressive infection. A relatively deficient immune responsiveness may allow progression to more severe and generalized disease (RPP). Suggestions are made for studies needed to confirm suspected pathogenetic mechanisms, approach resultant targeted therapies, and test hypotheses for contrasting roles of immune reactions in different clinical expressions of periodontitis.

Measurement of relative avidity of antibodies reactive with Porphyromonas (Bacteroides) gingivalis in the sera of subjects having adult periodontitis

Relative avidities of antibodies to Porphyromonas (Bacteroides) gingivalis in the sera of 15 patients having adult periodontitis and 15 healthy subjects were evaluated using an ammonium thiocyanate-dissociated ELISA. Graded concentrations of ammonium thiocyanate were added to a single dilution of serum in order to dissociate low avidity antibody binding to P. gingivalis. The concentration of thiocyanate resulting in 50% reduction in binding (absorbance) was termed the ID50 for that serum. When IgG-class antibodies were examined, the ID50 of anti-P. gingivalis antibodies in the sera of patients was significantly elevated (0.96M vs 0.71M; p less than 0.01, Student's t-test). In contrast, when IgM-class antibodies were examined no significant differences in ID50 between patients and controls were found for P. gingivalis (0.54M vs 0.53M). While the ID50 values of patient antibodies were found to be elevated relative to those of healthy controls, comparison with antibodies from rabbits immunized with P. gingivalis and with ID50 values from other human studies suggests that adult humans, in general, produce very low-avidity antibodies to P. gingivalis. It is suggested that the presence of low-avidity antibodies contributes to the pathology associated with periodontal disease.

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.

Porphyromonas gingivalis-specific serum IgG and IgA antibodies originate from immunoglobulin-secreting cells in inflamed gingiva

Patients with adult periodontitis (AP) exhibit elevated serum antibody levels to Porphyromonas (Bacteroides) gingivalis; however, it is not known whether these antibodies originate from plasma cells in the local disease site or from peripheral lymphoid tissues. We studied the isotype and subclass levels and origin of antibodies to P. gingivalis fimbriae, since elevated serum anti-fimbriae responses were seen when compared with sera of healthy controls. IgG anti-fibriae titres were dominant and the subclass response was IgG3 much greater than IgG1 greater than IgG2 much greater than IgG4; however, some IgA anti-fimbriae antibodies were also seen. The IgA subclass fimbriae-specific response was mainly IgA1; however, significant IgA2 anti-fimbrae antibodies were seen. We also assessed numbers of anti-fimbriae antibody producing cells from peripheral blood mononuclear cells (PMBC) and from either healthy or inflamed gingiva of AP subjects. Gingival mononuclear cells (GMC) of AP patients exhibited high numbers of immunoglobulin-producing (spot-forming) cells (SFC) including fimbriae-specific antibody secreting cells in a pattern of IgG greater than IgA greater than greater than greater than IgM. However, low numbers of SFC were seen in GMC from healthy gingiva; further, no anti-fimbriae SFC responses were noted in healthy GMC. Although no fimbriae-specific immunoglobulin-producing cells were seen in PBMC, low numbers of antigen-specific SFC were found in pokeweed mitogen-triggered PBMC from AP subjects. Treatment of AP patients for plaque and surgical removal of inflamed gingiva resulted in significant reductions in serum anti-fimbriae responses. These studies show that AP patients exhibit brisk serum IgG and IgA subclass anti-fimbriae antibodies, whose origin appear to be the plasma cells present in the localized inflamed tissues.

Acute-phase protein detection and quantification in gingival crevicular fluid by direct and indirect immunodot

The development of an assay for markers of active periodontitis, obtained directly from gingival crevicular fluid (GCF) and simply quantified, would be of great importance to the dental practitioner. The purpose of this study was to evaluate direct and indirect immunodot techniques as to their potential in easily quantifying acute-phase proteins within periodontally diseased and healthy site GCF. Indirect immunodots (GCF eluates dotted onto nitrocellulose membrane) using monoclonal antibodies and a radioactive isotope label were used to identify and establish relative amounts of C-reactive protein (CRP) and alpha-2-macroglobulin (A2M) in 2 diseased and 2 healthy sites in 24 periodontitis patients. Periodontally diseased sites were found to contain significantly lower concentrations of A2M than healthy sites (p less than 0.001), but CRP levels did not vary significantly between healthy and diseased locations. Using a direct immunodot assay (GCF absorbed directly into nitrocellulose membrane strips), A2M levels quantified with radioactive isotopes at healthy and diseased sites could be correlated with A2M levels determined by enzyme-linked antibody-colormetric probes at those same sites. Such a direct sampling and quantification system shows promise for future "in-office" diagnostic methodology.

Crevicular IgG antibodies and Streptococcus mutans on erupting human first permanent molars

The specific IgG antibody activity against indigenous Streptococcus mutans in gingival crevicular fluid (GCF) was determined in 25, 6-7-yr-old children. Samples of plaque and GCF were collected from all erupting first permanent molars. Plaque samples were also collected from the adjacent second primary molars. The presence of clinical caries was scored as defs. In the same individual a highly significant correlation (p less than 0.005) was found between the level of specific antibody activity in GCF when comparing first permanent molars with each other. No correlation was found between the specific antibody activity in GCF and the number of indigenous Strep. mutans colonizing the buccal surfaces of the first permanent molars. Caries-free children had significantly less specific antibody activity in GCF than children with caries experience (p less than 0.05). In the same child a highly significant correlation (p less than 0.0001) was found between the level of colonization by mutans streptococci on the permanent molars and the adjacent second primary molars.

Within-mouth correlations for indicators of the host response in gingival crevicular fluid

Gingival crevicular fluid was collected from multiple sites in patients with chronic adult periodontitis, and analysed for the lysosomal enzymes beta-glucuronidase and arylsulphatase, the cytoplasmic enzyme lactate dehydrogenase, total IgA, IgG and IgM and the protease inhibitor alpha 2-macroglobulin. The within-mouth (intraclass) correlation coefficients were calculated to describe the relationship between samples collected from individual patients. Data collected at baseline and 3 months after root planing and scaling were analysed, as was the change between examinations. Volume of crevicular fluid demonstrated the smallest intraclass correlation coefficient (0.16 at baseline, 0.12 at 3 months; 0.11 change), while probing depth and enzyme activity had moderate intraclass correlations (i.e. 0.36, 0.36, 0.26 for beta-glucuronidase). Immunoglobulin and alpha 2-macroglobulin activity in the fluid had the strongest correlations (i.e. 0.64, 0.57, 0.65 for IgG). The correlations for anatomically related teeth within a quadrant (molar, non-molar) were equivalent to or greater than the correlation for all samples within a mouth. Examined by tooth type, the intraclass correlations for volume of crevicular fluid, probing depth, beta-glucuronidase, arylsulphatase and lactate dehydrogenase were higher for non-molar teeth. In contrast, intraclass correlations for IgA, IgG, IgM and alpha 2-macroglobulin in samples from molar teeth were either equivalent to or greater than the correlations for non-molar samples. Calculation of intraclass correlation coefficients for such data can (1) indicate the degree of variability present in multiple samples of crevicular fluid collected from individual patients, (2) provide information about the source of host mediators in the fluid, and (3) help identify appropriate sampling strategies for the fluid.

Humoral immune response to Bacteroides gingivalis fimbrial antigen in mice

Bacteroides gingivalis fimbrial antigen incorporated into liposomes, but not in Tris-HCl buffer, significantly raised the levels of anti-fimbriae antibodies in serum, particularly of the IgG class, after oral primary and booster immunizations in BALB/c mice. An approximately linear relationship was observed between the dose of fimbrial antigen and the level of fimbriae-specific antibodies produced; antibody production reached its maximum at an immunization dosage of 500 micrograms of fimbriae per mouse. Fimbriae-specific antibody production was enhanced by use of a semi-synthetic adjuvant, a stearoyl derivative of sodium beta-N-acetylglucosaminyl-(1----4)-N-acetylmuramyl-L-alanyl-D-isoglutaminyl-(L) - stearoyl-(D)-meso-diamino-pimelic acid-(D)-amide-D-alanine (GM)-53) in liposomes. High anti-fimbriae antibody levels in serum and saliva were maintained for several months in the mice that had received two orally administered boosters of fimbrial antigen with GM-53 in liposomes. Salivary anti-fimbriae antibody levels, particularly of the IgA class, were markedly raised.

Antibody-forming cell induction during an early phase of germinal centre development and its delay with ageing

The present study was initiated to determine if an early phase of germinal centre (GC) development is associated with the generation of antibody-forming cells (AFC). Germinal centres in draining lymph nodes from immune mice were examined histochemically after secondary immunization for the presence of AFC at both the light and electron microscopic levels. Additionally, peanut agglutinin (PNA) high (Hi) GC B cells were isolated, placed in cell culture and specific antibody production was monitored at successive intervals. Electron microscopy showed that plasma cells in all stages of differentiation were present within GC at 3-5 days and to a lesser extent at 7 days following antigenic challenge. Furthermore, PNAHi GC B cells obtained between Days 3 and 5 spontaneously produced specific IgG when placed in culture. Germinal centre B cells isolated either before or after this period did not produce antibody without the addition of T-cell cytokines. Induction of AFC in GC occurred at the time when GC B cells acquire follicular dendritic cell (FDC)-derived, immune complex-coated bodies (iccosomes) and process and present this antigen to helper T cells. This suggested a causal relationship between iccosome release and AFC induction. Support for this was obtained by examination of AFC induction in aged mice where iccosome release has not been observed. Peanut agglutinin-positive GC B cells isolated from aged mice on Days 3-5 after antigen challenge failed to spontaneously produce specific antibody. Collectively, these data show that GC development 3-5 days after booster immunization results in AFC generation and suggests a role for FDC iccosomes in their induction.

A comparison of antibody levels to Bacteroides gingivalis in serum and crevicular fluid from patients with untreated periodontitis

The levels of IgG antibody to Bacteroides gingivalis were measured in serum and sequential samples of crevicular fluid from healthy and diseased sites in patients with untreated periodontitis using ELISA. All subjects had detectable serum titres but there was a wide variation in titre between subjects. Moderate to strong correlations were found between serum and crevicular fluid levels of IgG. A statistically significant difference was observed between sequential samples of crevicular fluid. There was no difference in the level of specific IgG to B. gingivalis in crevicular fluid between healthy and diseased sites within the same individual.

Polyclonal B-cell activation in periodontitis

The evidence that periodontitis-associated bacteria contain potent PBA factors is very strong. Clearly, antibodies directed against non-oral antigens are produced in the inflamed periodontal lesion, and PBA appears to contribute to that production. It is also clear that B cells and plasma cells are the major cell types in the periodontal lesion. Furthermore, alterations in the regulation of B-cell responses to PBA factors are associated with severe periodontal disease. However, evidence demonstrating that activated B cells and plasma cells are directly involved in the pathogenic mechanisms leading to destruction of the periodontal support is still circumstantial. Polyclonal B-cell activation and potential pathways by which PBA-stimulated cells could be involved in periodontal destruction remain largely hypothetical. It appears that IL-1 is an important osteoclast-activating agent, and that LPS, which is a potent PBA factor in many systems, can elicit IL-1 production by B cells as well as by the monocyte/macrophage lineage. Recent data indicating that IL-1 is produced by numerous malignant B-cell lines lend support for the idea that B-cell IL-1 could be important in bone resorption. It is also likely that polyclonal activation may lead to production of autoantibody such as anti-type I and anti-type III collagens, and the destruction of self tissues through ADCC reactions, immune complex formation, and complement activation. Further research is needed to determine how the B cell/plasma cell may participate in tissue injury in periodontitis, and how the B-cell response to PBA factors is regulated.

Immunodominant antigen of Actinobacillus actinomycetemcomitans Y4 in high-responder patients

This study was undertaken to look for characteristics of the immunodominant antigen(s) of Actinobacillus actinomycetemcomitans Y4 that might help explain the high antibody titers in periodontitis patients. Radioimmunoassays (RIA) were performed on sera from 481 patients; sera from the 32 patients with the highest anti-Y4 titers (above 128,000 RIA U/ml) were further analyzed. Y4 antigen was boiled for 45 min or treated with papain, and antibody responses were analyzed by RIA and Western blotting (immunoblotting). In addition, carbohydrate was purified from Y4 and examined by Western blotting. The results indicated that the immunodominant antigen of Y4 in high responders was stable after papain treatment or boiling for 45 min. Papain or boiling eliminated protein bands but a large diffuse band persisted on Western blots. With increasing dilutions of sera, bands on Western blots corresponding to protein antigens disappeared, while the large diffuse band resembling that of carbohydrate persisted. Partially purified Y4 carbohydrate contained the large diffuse band. Double-immunodiffusion analysis indicated that rabbit serotype b-specific antiserum and patient sera recognized the same antigen. When the carbohydrate extract was passed over a lipid A-binding column to remove lipopolysaccharide, the smear corresponding to the immunodominant antigen was still present on Western blots. The immunodominant antigen of Y4 in high-responder individuals appears to be a carbohydrate and is possibly the capsular polysaccharide.

The effect of sequential sampling on crevicular fluid volume and enzyme activity

Gingival crevicular fluid (GCF) volume and constituents in static samples were compared to volume and constituents in subsequent GCF samples collected during a 60-min interval. Using deep intracrevicular placement of precut filter paper strips, GCF was collected from interproximal and facial sites from patients with gingivitis (N = 14; 28 interproximal sites, 28 facial sites) and chronic adult periodontitis (N = 11; 26 interproximal sites, 18 facial sites). The strips were inserted for 30 s at 0, 4, 8, 30 and 60 min. The amount of fluid on each strip was determined and microspectrophotometric techniques were used to assess cytoplasmic and lysosomal enzyme activity. Within each group of sites, mean GCF volume showed minimal fluctuation with repeated sampling. In contrast, the static GCF sample contained the greatest amount of total enzyme activity, and differences were detected between groups. The interproximal sites and the gingivitis-facial sites displayed a similar pattern of change in total enzyme activity during the test period. The highest total enzyme activity was observed in the first sample and decreased at 4 and 8 minutes. At 30 and 60 min, the amount of enzyme either remained at the level detected at 8 min, or displayed a mild tendency to recover towards baseline. A different pattern of total enzyme activity was observed for the periodontitis-facial sites, where a significant decrease was first observed at 30 min. Enzyme concentration was higher in the facial sites than the interproximal sites, and enzyme concentration was generally highest in the static samples. The concentration data, however, is difficult to interpret since a number of sites demonstrated a converted GCF volume of 0 microliter. Our data suggests that total enzyme activity and enzyme concentration are generally greater in the static GCF samples compared to subsequent samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteroides-specific IgG and IgA subclass antibody-secreting cells isolated from chronically inflamed gingival tissues

The emergence of cells that produce IgG and IgA subclass antibodies to Bacteroides gingivalis (Porphyromonas gingivalis) fimbriae and lipopolysaccharide (LPS) antigens was examined in mononuclear cells isolated from inflamed gingiva of different stages (slight, moderate or advanced) of adult periodontitis (AP). Antigen-specific IgM, IgG (including IgG1, IgG2, IgG3 and IgG4) and IgA (including IgA1 and IgA2) producing cells were enumerated by the ELISPOT assay and were compared with total Ig-producing cells of each isotype or subclass. In advanced AP, the B. gingivalis fimbriae-specific IgG- and IgA-secreting cells represented 5% of total IgG- or IgA-secreting cells, while those from the moderate stage comprised approximately 1% of these two isotypes. Cells producing antibody specific for B. gingivalis LPS were observed at frequencies of 0.1% and 0.4% for IgG and IgA cells, respectively in the advanced stage. When IgG subclasses were analysed in moderate AP, the anti-fimbriae subclass responses were largely IgG1 (60%), followed by IgG2 (20%), IgG3 (10%) and IgG4 (10%). Fimbriae-specific IgG subclass responses were elevated in the advanced stage of AP, and IgG4 (40%) and IgG1 (30%) were dominant, followed by IgG3 (20%) and IgG2 (10%). IgA1 cells predominated in both the moderate and advanced stages, however a relative increase in IgA2 cells occurred in advanced AP. Mononuclear cells isolated from gingiva of AP patients did not contain cells producing antibody to antigens such as Escherichia coli K235 LPS, cholera toxin or the hapten dinitrophenyl coupled to bovine serum albumin. These results show that local IgG and IgA subclass responses occur to a protein antigen of a major periodontal disease (PD)-associated pathogen, B. gingivalis, and the increase in IgG4 and IgA2 responses may be associated with host protection.

IgG subclasses in gingival crevicular fluid from active versus stable periodontal sites

Since IgG subclasses are common immunoglobulins associated with the periodontium and have different biological characteristics, these subclasses were measured in gingival crevicular fluid (GCF) from periodontally active (greater than or equal to 2 mm clinical attachment loss within three months of sample) versus clinically similar but stable or healthy sites. A sandwich enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies was performed to quantitate IgG subclass and albumin concentrations in serum and interproximal GCF samples from at least one each of the three disease categories from each of 20 periodontal maintenance patients. Although much variability existed among sites, mean IgG1 (p less than 0.05) and IgG4 (p less than 0.01) concentrations were higher in GCF from active periodontitis areas than stable sites, even though both had similar clinical characteristics. When IgG subclass concentrations were adjusted per mg albumin, both IgG1 and IgG4 levels in GCF from active sites were still significantly elevated over stable areas (p less than 0.05). Mean adjusted concentrations in GCF were generally greater than in serum, especially for IgG4 (active site GCF:serum = 24.2:1). GCF IgG4 concentrations may be useful as an indicator of the immunopathological changes which occur in active periodontitis.

Antibody synthesis specific for nonoral antigens in inflamed gingiva

In vitro experimentation indicates that periodontitis-associated bacteria contain potent polyclonal B-cell activators (PBA). We reasoned that if PBA were operative in vivo, plasma cells specific for nonoral antigens should be present in the inflamed gingival tissues, which are characterized by a plasma cell infiltrate. To test this, rabbits with experimental periodontitis were immunized in the hind legs with the histochemically detectable antigen horseradish peroxidase (HRP) or glucose oxidase (GO). At various times after secondary immunization, inflamed gingival tissue was removed, sectioned, and treated histochemically to reveal plasma cells that specifically bound HRP or GO. Remarkably, by 9 days after secondary immunization, hundreds of HRP- or GO-binding plasma cells were found in the inflamed gingival tissue of immunized rabbits. The presence of these plasma cells, observed 7 to 10 days after booster immunization, was further substantiated by the presence of large amounts of locally produced HRP- or GO-specific antibody in gingival crevicular fluid. By 1 month after secondary immunization, the number of antigen-binding plasma cells had decreased dramatically, but a small number of antigen-specific plasma cells were detected for as long as 9 months after secondary immunization. The large number of HRP- or GO-specific plasma cells observed 9 days after immunization led us to see whether recently stimulated cells were more susceptible to PBA. Peripheral blood lymphocytes (PBL) were obtained at different times after booster immunization and cultured in the presence or absence of a PBA from Fusobacterium nucleatum. At 7 days after immunization, PBL spontaneously differentiated into antibody-forming cells in culture, and this process was enhanced by PBA. In contrast, PBL taken months after immunization produced little antibody in culture, and enhancement by PBA was difficult to detect. Compared with resting B cells, the recently stimulated B cells clearly differentiated more readily into antibody-forming cells. In conclusion, antibody synthesis specific for nonoral antigens did occur in inflamed gingival tissue, and a number of mechanisms, including PBA, probably contributed to this phenomenon.

Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans in human periodontal diseases

Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans seem to be major pathogens in advancing periodontitis in man. First, these organisms are recovered in higher prevalence and proportions from progressive periodontitis lesions than from quiescent periodontal sites. Second, antibody levels against B. gingivalis and A. actinomycetemcomitans are markedly elevated in serum and gingival crevice fluid of periodontitis patients compared to normal controls. Third, B. gingivalis and B. intermedius elaborate potent proteases and A. actinomycetemcomitans various noxious substances which have the potential to perturb important host defenses and to disintegrate key constituents of the periodontal tissues. Monitoring these bacteria in advanced periodontal lesions may greatly assist the assessment of treatment efficacy and risk of further periodontal breakdown.

Replacement therapy of the prevention of dental disease

Certain laboratory-derived and naturally occurring oral bacteria are promising effector strains for the replacement therapy of dental infectious diseases. In the case of dental caries, several types of low-acid-producing mutants of Streptococcus mutans and a natural variant of S. salivarius have been found that are virtually non-cariogenic. Laboratory rats can be readily and persistently infected with these micro-organisms. Once infected, the animals become much more resistant to infection by wild-type (disease-causing) strains of S. mutans. Thus, in the laboratory rat, replacement therapy has proved successful in providing lifelong resistance to dental caries following a single application of an effector strain. Attempts to extend these findings to humans have required a search for effector strains that can both colonize well and, in addition, displace indigenous, wild-type strains of S. mutans. A mutant of a strain of S. mutans producing a bacteriocin-like molecule has been found that appears to be well-suited for this purpose.

Replacement therapy may also find a practical application in the prevention and cure of certain periodontal diseases. Hydrogen peroxide-producing streptococci are invariably found in plaque taken from healthy gingiva; they are rarely found in samples from active disease sites of patients with juvenile or refractory periodontitis. In vitro, peroxide production by these streptococci inhibits the growth of Actinobacillus actinomycetemcomitans and several other presumed periodontal pathogens. Bacterial interactions of this sort have also been directly demonstrated to occur in vivo. Thus, natural inhibitors in plaque may be essential for maintenance of periodontal health. Patients lacking such inhibitors may be treated by replacement therapy to restore the composition of their plaque flora to one that is conducive to health.

Detection of specific antibodies against fimbriae and membrane proteins from the oral anaerobe Bacteroides gingivalis in patients with periodontal diseases

Sera from a number of patients with periodontal diseases were shown to have specific immunoglobulin G (IgG) antibodies against fimbriae and membrane proteins of Bacteroides gingivalis, a suspected pathogen, by using Western blottin analysis. The sera had a strong tendency to react with fimbriae, or exactly oligomeric structures of fimbriae with a native beta-structure rich-conformation. However, the sera did not react with fimbrilin, a constituent protein of fimbriae, which is denatured by sodium dodecyl sulfate.

Ultrastructural and immunocytochemical characterization of polymorphonuclear leukocytes from gingival crevice in man

Polymorphonuclear leukocytes from the gingival crevicular fluid (CF-PMNs) of patients with generalized severe periodontitis were examined using electron microscopy and immunocytochemical techniques. CF-PMNs were found to contain numerous phagocytic vacuoles. This suggests that CF-PMNs actively phagocytized various substances from the environment. Immunocytochemical staining with FITC-conjugated IgG, IgM, and IgA reagents and TRITC-conjugated C3 reagent was applied to CF-PMNs as well as peripheral blood PMNs incubated with cell-free crevicular fluid. The cytoplasm of PMNs exhibited numerous granular foci of immunofluorescence. This finding suggests that these proteins were acquired from the environment by PMNs. The coincidental appearances of immunoglobulins and C3 in a single cell were considered to be immune complexes phagocytized by CF-PMNs in generalized severe periodontitis.

Human serum antibody responses to oral microorganisms. IV. Correlation with homologous infection

Recent microbiological studies of periodontal disease in humans have supported the concept of a specific bacterial etiology. While individual agents have not been unequivocally identified, numerous Gram-negative members of the subgingival microflora have been implicated. In addition, elevations in systemic antibody responses have been consistent with certain oral microorganisms being involved in an infectious process associated with the disease. This report delineates the relationship between elevated systemic antibody levels and oral colonization with the homologous microorganism at active disease sites. Thirty-four patients with various types of periodontal disease were examined. Using ELISA, each patient was shown to have an elevated antibody response to at least one organism from a battery of 18 oral microorganisms that were tested. Subsequently, subgingival plaque was cultured from disease-active and -inactive sites of each subject. The results demonstrated that the same microorganism to which the individual exhibited elevated serum antibody responses was detected in nearly 55% of the disease-active sites, while only 18% of the inactive sites showed the microorganism. Certain microorganisms including Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Eikenella corrodens and Wolinella recta were primarily or exclusively correlated with active disease lesions. These findings support the hypothesis that elevated systemic antibodies to periodontopathic bacteria are reflective of subgingival colonization and exist as a response to a bacterial infection at disease-active sites.

Salivary immunoglobulin concentrations in predentate and edentulous mouths

The concentrations of IgA, IgG and IgM in whole saliva of predentate babies, dentate adults, and edentulous old people, and the salivary IgG concentration of dentate old people, were determined using a solid phase radioimmunoassay. A highly significant difference in IgG concentrations was found between toothless and dentate people. The average IgG concentration in the saliva of edentulous old people was 5.2 mg/1, which was about 20% of that of dentate old people. The salivary IgG content of babies was only 1.7 mg/1, which was in concordance with the low postnatal serum IgG values. The salivary IgA level in this age group was also low. The edentulous old people tended to have decreased IgM values, and the predentate babies tended to have increased IgM values compared with the dentate adults.

Possible mechanisms involved in the immunoregulation of chronic inflammatory periodontal disease

It is generally agreed that immunological mechanisms are involved in the pathogenesis of periodontal disease; however, regulation of these mechanisms has hitherto received scant attention. Regulatory networks exist at both a cellular and a molecular level. At the cellular level, the existence of helper (T4-positive) and suppressor (T8-positive) T lymphocytes, the expression of Class II major histocompatibility complex antigens, and the heterogeneity of macrophage subpopulations are central to an understanding of the regulatory mechanisms involved. It is only recently that studies of these separate components, in both humans and experimental animals, have begun to provide a basis for understanding the complex interactions occurring in periodontal disease. Studies using the human experimental gingivitis model have shown an immunoregulatory picture consistent with a controlled immunological reaction with an essentially normal T4:T8 ratio of 2.0. In contrast, studies utilizing cells extracted from adult periodontitis lesions have shown a reduced T4:T8 ratio (approximately 1.0) and an inability to respond in, or to stimulate, an autologous mixed lymphocyte reaction. Animal studies using athymic nude rats have supported the concept of a central role for T-cell control in periodontal disease and the possibility of an imbalance in this control with disease progression. These results are reviewed and areas of future research explored.

Inhibition of gingival fibroblast growth by Bacteroides gingivalis

Human gingival fibroblasts were exposed in culture to cell extracts of different black-pigmented Bacteroides species, and their growth was monitored by determining thymidine uptake and counting cells. Of the Bacteroides species tested (B. gingivalis, B. asaccharolyticus, and B. intermedius), B. gingivalis gave the extract with the strongest inhibitory effect on fibroblast thymidine uptake. Linear inhibition reaching 80% of the control level was obtained with a dose of 100 micrograms of B. gingivalis extract protein per ml. The effect of B. asaccharolyticus resembled that of B. gingivalis, but even at the highest dose tested B. intermedius had only a slight inhibitory effect. When fibroblasts were counted after 2- and 4-day exposures to B. gingivalis extracts, a clear depression in the number of fibroblasts was found. The effects of extracts obtained from early and late growth phases of B. gingivalis cultures were similar. A fraction of B. gingivalis consisting essentially of lipopolysaccharides (LPSs) was obtained by degrading the extract proteins with proteinase K. Silver staining of polyacrylamide gels revealed a LPS pattern with a molecular mass ranging from 37 to 60 kilodaltons. This LPS-rich fraction caused inhibition of thymidine uptake by gingival fibroblasts similar to that caused by the native extract alone. Thus, the inhibition of gingival fibroblast growth by B. gingivalis appeared to be LPS mediated. This inhibitory effect of B. gingivalis on oral fibroblast growth may be a virulence factor of this bacterium.