Polyclonal B-cell activation: severe periodontal disease in young adults

Studies of proliferative responses by long-term-cryopreserved peripheral blood mononuclear cells to bacterial components associated with periodontitis

Freezing techniques provide a means for repeating and extending immunological assays with frozen aliquots of an individual's peripheral blood mononuclear cell fraction. Lymphocytes which are stored frozen for a limited time retain their ability to respond to polyclonal B-cell activators, mitogens, and antigens of dental interest. Our studies extend these previous findings by determining lymphocyte functional activity following frozen storage for up to 100 weeks. In addition, the autologous immune response was measured by spontaneous lymphocyte proliferation following 0, 1, 40, and 60 weeks of frozen storage. Peak responses for all individuals occurred at day 7 of incubation. The lymphocyte proliferative response to the superantigens toxic shock syndrome toxin-1 (TSST-1) and Staphylococcus enterotoxin A (SEA) were not changed after 100 weeks of frozen storage. Maximum responses varied among the individuals but occurred at equivalent stimulator concentrations. However, slopes generated from data obtained following 0, 4, 13, 20, 30, 50, 88, and 100 weeks of frozen storage showed no significant deviation from zero (P > 0.05) for all individuals tested. After 100 weeks of storage, the total changes in proliferative activity (counts per minute per week) were -2.1% +/- 16.8% and -5.5% +/- 17.0% for TSST-1 and SEA, respectively. The lymphocyte proliferative responses to pokeweed mitogen, concanavalin A, and sonicates of two periodontal pathogens (Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans) following frozen storage were similar to those with TSST-1 and SEA. These results indicate that peripheral blood mononuclear cells stored frozen may serve as appropriate controls to monitor changes in the disease state long-term periodontal treatment.

Prostaglandin E2 regulates gingival mononuclear cell immunoglobulin production

Histological studies have revealed elevated levels of T and B lymphocytes in inflamed gingival tissue. Functional analysis of these B cells has determined that they are spontaneously secreting large amounts of immunoglobulin. Several components of bacterial plaque which accumulate during the onset of periodontal disease induce polyclonal B cell activation, and are most likely responsible for the "hyperactive" state of these gingival B lymphocytes. In addition to this exaggerated humoral response, increased levels of inflammatory mediators, such as prostaglandin (PG) E2, have been implicated in the pathogenesis of disease. Therefore, the purpose of this study was to determine if PGE2 could regulate immunoglobulin production within inflamed gingival tissue. Specimens were harvested during routine surgery of patients with chronic adult periodontitis. Utilizing an ELISA, elevated levels of IgG were detected in the supernatant of cultured gingival mononuclear cells. Inclusion of indomethacin, which inhibits arachidonic acid metabolites such as PGE2, caused a decrease in IgG levels. PGE2 exerted a biphasic effect upon IgG production, with high doses diminishing and low doses increasing IgG levels. From a clinical perspective, these results suggest that elevated levels of PGE2 associated with inflammation will attenuate an IgG response and, as PGE2 production wanes, the local humoral response will rebound. Interestingly, the combination of low dose PGE2 and IL-4 induced a synergistic rise in IgG production. These findings support the theory that local PGE2 levels can regulate immunoglobulin production and potentiate cytokine induced class switching within gingival tissue.

Serum and gingival crevicular fluid anti-desmosomal antibodies in periodontitis

SDS polyacrylamide gel electrophoresis separates desmosomal proteins and glycoproteins of bovine tongue epithelium by their relative molecular mass. The Western immunoblot technique was used to reveal the reactions of desmosomal proteins and glycoproteins with naturally occurring antibodies in serum and gingival crevicular fluid (GCF). Naturally-occurring serum and GCF antibodies (IgG and IgM) from periodontitis patients and healthy, unaffected controls reacted with desmosomal proteins (desmoplakins) and glycoproteins (desmogleins). Sera from 90% of subjects with periodontitis showed increased reactions of IgG with desmoplakins (240 and 210 kDa) and 80% with desmogleins (165, 130, and 115 kDa), when compared with unaffected controls. Patients' IgG reacted with desmosomal components more strongly than IgM. IgG antibodies against desmosomal antigens in GCF showed similar specificities from patients and healthy subjects and to their serums. When GCF within individuals with periodontitis was compared, anti-desmosomal IgG from diseased sites showed greater reactivity than healthy controls. These data suggest that anti-desmosomal antibodies are a normal part of the immune repertoire. The presence of elevated titers of anti-desmosomal antibodies appear to distinguish periodontitis from unaffected sites. When detected, elevated titers of anti-desmosomal antibodies may contribute to the pathogenesis and indicate increased risk of periodontitis.

In situ characterization of gingival mononuclear cells in rapidly progressive periodontitis

Rapidly progressive periodontitis (RPP) has been suggested as a distinct clinical entity within the spectrum of early onset periodontitis. Immunological mechanisms have been considered in the pathogenesis of RPP. This study was designed to evaluate the distribution and phenotypic properties of the lymphocyte populations within the affected gingival tissue of patients with RPP. Biopsies were obtained from 16 patients between 22 and 33 years of age. The tissue samples were processed for both histopathological and immunohistochemical examinations. Gingival tissue T lymphocytes (CD3+), helper T cells (CD4+), suppressor-cytotoxic T cells (CD8+), and cells positive for HLA-DR antigen were identified using monoclonal antibodies with an immunoperoxidase technique. Intracytoplasmic immunoglobulin-containing cells were also stained immunohistochemically with polyclonal antibodies. CD3+ cells were mainly located beneath the pocket epithelium. CD4+ and CD8+ cells were evenly distributed within this T-cell infiltrate with a CD4+/CD8+ ratio of 1:12. Numerous HLA-DR+ cells were also observed in the lymphocytic infiltrates. The majority of mononuclear cells located throughout the stroma were IgG+ plasma cells. Our results indicate that RPP patients present an IgG-bearing plasma cell dominated lesion with equal participation of both T-cell subpopulations. These findings suggest that activation and proliferation of B-cells play an important role in the pathogenesis of periodontal diseases.

Differential diagnosis in clinical trials of therapy for periodontitis

For purposes of clinical trials of therapies for periodontitis, it is recommended that population samples be identified as adult periodontitis (systemically modified or not systemically modified), early onset periodontitis (localized or juvenile, generalized or rapidly progressive, or associated with systemic disease), or necrotizing ulcerative periodontitis, avoiding overlapping criteria. Population samples of adult or early onset periodontitis modified by or associated with systemic conditions should be used in clinical trials only when the intent is to study effect on the specifically modified condition. Objective identification of the modifying systemic condition should be required for all subjects in such trials. Population samples should be homogeneous for the diagnosis, whether systemically modified or not. Refractory periodontitis, prepubertal periodontitis, and periodontitis associated with systemic disease are not recommended as useful descriptors of population samples without discrete identification of underlying systemic abnormality for all included subjects. Definition of population sample by a bacteriological or a host response feature is not recommended unless the trial is specifically aimed at that feature and the sample is homogeneous for it. All trials of efficacy should include physical or radiographic measurement of attachment level or bone height as a critical outcome variable. Results from trial in one form of periodontitis should not be applied directly to other forms.

Gingivitis/stomatitis in cats

Any alteration in the balance of bacterial challenge versus the host's ability to resist and repair will result in oral lesions that are similar in appearance. The bacterial cause of gingivitis and periodontitis in humans and in all other animals in which it has been studied is firmly established, and specific species of predominantly gram-negative anaerobes have been implicated. Naturally occurring or acquired immunopathologies are likely to result in premature dental disease. When oral disease is associated with the accumulation of plaque, a positive response can be achieved by reducing the bacterial challenge to the host through the maintenance of oral hygiene by timely professional dental prophylaxis and home care. Disease that is the result of atypical immune responses, however, can be much more difficult to manage. Such oral disease can occur with either immune deficiencies or exaggerated immune responses, and it is likely that multiple mechanisms are active concurrently. In any case, gram-negative anaerobes present in plaque are likely to be a major contributing factor. Therefore patients with chronic refractory gingivitis-stomatitis must be considered to be plaque intolerant. Only with a frequent regimen of aggressive and thorough professional dental treatment plus meticulous oral home care on a daily basis can one expect to keep these cases in remission. Because this is often unrealistic, the only other way to keep these patients free of disease is by total dental extraction. The tissues that are colonized by the causative organisms must be eliminated. All root tips and bony sequestra must be removed and healing with intact epithelium accomplished before these cases will go into remission. Edentulous feline patients that continue to have signs of gingivostomatitis have been found to have an area of nonhealed bony sequestrum and chronic osteomyelitis. Once effective debridement has been accomplished and epithelial healing completed, nonresponsive cases can be expected to go into remission (Color Plate 2, Figure 7). It is hoped that as more is learned about this frustrating problem, the many factors influencing feline oral disease will be scientifically documented. In the future, actual diagnoses can be systematically made early on in disease, and treatment will be more than just symptomatic.

Immunity to self-antigens in periodontal disease

Auto-antibody to collagen, previously detected in periodontal disease, may represent either a response to local tissue damage or be the manifestation of a disturbance of the host immune response induced by the periodontal flora and its products. In an effort to distinguish between these two hypotheses, this study was undertaken to determine circulating IgG auto-antibody levels in 41 periodontal-disease patients against 12 self-antigens (salmon DS-DNA, calf SS-DNA, human and bovine thyroglobulin, rabbit proteoglycan, horse myoglobin, bovine myosin, actin, fetuin, human transferrin, cytochrome C, and human Type I collagen) and compare them to those in 21 periodontal disease-free subjects. None of the detected IgG auto-antibody levels were significantly different between periodontal disease and control sera (Mann-Whitney U-test, P greater than 0.05) except for human Type I collagen (P less than 0.05). Fifty-six percent of patients and 38% of controls were "broad responders;" i.e., 50% or more of the auto-antibody levels were higher than the median values of the control group; however, these values were not significantly different using the chi-square test. It was concluded that the destruction of connective tissue components is the primary driving force in the induction of the enhanced auto-antibody response found in periodontal disease. This response is apparently secondary to the primary bacterial infection which remains the major etiologic event.

Autoimmunity to collagen in adult periodontal disease: immunoglobulin classes in sera and tissue

The immunoglobulin class distribution of antibody to human collagen type I has been examined in sera and gingival extracts from patients with adult chronic periodontitis. Tissue extracts were made either by simple washing or ultrasonication. With either method, IgG and IgA antibodies to collagen were present in higher concentration in tissue extracts than in autologous serum when adjustment was made for dilution differences. No significant differences were found for IgM antibodies. Antibodies to human collagen type I are usually "natural antibodies" of the IgM class and, therefore, our findings suggest a class switch to IgG in inflamed gingivae, presumably due to prolonged antigenic stimulation.

Diagnosis of periodontal diseases

This paper reviews current (Fall, 1990) information related to the diagnosis of periodontal diseases. As background, principles of diagnostic decision-making and conceptual shifts during the 1970's and 1980's are reviewed in brief. "Diseases" that appeared in many classification schemes for periodontal diseases in the early 1970's--for example, "periodontosis" and "occlusal trauma"--do not appear in most current classifications. A recent (1989a) classification recommended by the American Academy of Periodontology holds that "periodontitis" includes several different diseases. There is, indeed, evidence for several different forms of periodontitis, but the AAP's classification does not conform to the principles of diagnostic decision-making because of the significant overlap between and heterogeneities within its suggested "diseases". An alternative classification is suggested, based on a concept that the periodontal diseases are mixed infections whose outcome is modified by relative effectiveness of host response. This view suggests that the most usual forms, gingivitis and adult periodontitis, normally occur in persons with essentially normal defense systems. Variation in extent or severity of disease can be understood as a function of the local infection in hosts with various degrees of compromised resistance to the infection. Early-onset periodontitis (EOP) cases could be accounted for by those where host response is abnormal to some significant degree. The greater the abnormality, the greater the extent and severity of disease might be. Localized EOP cases would be those where a relatively effective specific response intervenes to ameliorate progress of disease after the initially rapid progression. Other issues are detection of disease activity and assessment of risk for disease progression. Non-cultural bacteriological tests are available, but have not yet been shown to detect or predict activity or risk. One difficulty in reaching such proof for those or other tests has been the lack of an appropriate "gold standard" for disease activity or progression. This is being remedied by development of improved automated probes and imaging technologies. Considerable effort is being devoted to determining whether factors in gingival crevicular fluid may have diagnostic utility. More evidence is needed before clinical utility is known, but several enzymes and cytokines have potential for aiding diagnostic decisions.

Accumulation of plasma cells in inflamed sites: effects of antigen, nonspecific microbial activators, and chronic inflammation

Plasma cells are common in chronically inflamed sites, including periodontal lesions. The aim of this study was to determine which factors contribute to this local accumulation of plasma cells. Specifically, we sought to evaluate the effects of specific antigen and nonspecific activators from an infectious agent associated with chronic inflammation (Fusobacterium nucleatum, an organism prominent in chronic periodontal lesions) and the effect of the chronic inflammation itself. Chronic inflammation (14 to 17 days) was induced in horseradish peroxidase (HRP)-immune rabbits by subcutaneous injection of 50 microliters of sterile alum in several sites in their backs. Controls included sites injected with saline or more acute sites examined after 3 days of alum inflammation. Sites were challenged with HRP (the antigen), sonicated F. nucleatum (the nonspecific activator), or both together to see whether F. nucleatum has an adjuvant effect. Three days after challenge, HRP-specific antibody-forming cells (AFC) were enumerated after peroxidase histochemistry. In noninflamed sites or sites with acute inflammation, virtually no HRP-specific AFC were evident. In contrast, chronic inflammation alone was sufficient to elicit a specific AFC response (congruent to 10 cells per mm2). Addition of either F. nucleatum or HRP to the chronic lesion about doubled the number of HRP-specific AFC. However, a dramatic 8- to 15-fold (80 to 150/mm2) increase was seen in chronically inflamed sites challenged with antigen and activator together. Interestingly, the activator did not have this adjuvant effect in the acute sites or in normal skin. In short, accumulation of plasma cells in inflamed sites is promoted by chronic inflammation, activators of microbial origin, and specific antigen. This milieu can be expected to develop in some periodontal lesions and could help explain why gingival crevicular fluid from some sites may contain extraordinary levels of locally produced specific antibodies for certain antigens.

Rheumatoid factor (RF) distribution in periodontal disease

This study investigated the occurrence of an autoantibody, IgM rheumatoid factor, that may result from the chronic inflammation noted in periodontal disease and rheumatoid arthritis. In order to detect IgM-RF, a biotin-avidin ELISA was developed. This assay was found to be sensitive and accurate by testing a rheumatoid arthritis population. The characteristics of this rheumatoid arthritis group were further determined, such that the total serum immunoglobulin concentrations were slightly elevated although within the normal range for IgM, IgG, and IgA; IgG antibody levels were elevated against oral microorganisms of the genus Capnocytophaga, while elevated IgM antibody levels were noted to Bacteroides species. In a population of 260 subjects of which 171 were periodontal disease patients, 16 of 171 (9.4%) were seropositive for IgM-RF, of which the predominant disease types were advanced destructive periodontitis and adult periodontitis. For comparison, a random population of seronegative periodontal disease patients was constructed that was matched for sex and approximate age to the seropositive group. The total immunoglobulin levels of the two groups were not significantly different and the means of both were slightly lower than the rheumatoid arthritis group. When the antibody profiles of the two periodontal disease populations were compared it became evident that the RF-positive group showed IgM and IgG antibody that was significantly elevated to Capnocytophaga species and F. nucleatum. Therefore, the chronic inflammation associated with periodontitis appears to increase significantly the formation of IgM-RF; however, there does appear to be a relationship between IgM-RF and elevated antibody to selected oral microorganisms.

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.

Phagocyte function in juvenile periodontitis

We studied the chemotaxis of peripheral blood polymorphonuclear leukocytes (PMNs) and monocytes and the production of tumor necrosis factor alpha by monocytes of patients with juvenile periodontitis (JP). As a group, the patients' PMNs showed significantly increased chemotaxis determined by counting the number of migrating cells within a 3-microns-pore-size filter. Determined as distance of migration within the filter, as chemotactic increment based on checkerboard analysis, as leukotactic index calculated on the basis of distance of migration and cell count at different depths within a 3-microns-pore-size filter, as distance of migration under agarose, and as the number of PMNs migrating across a 5-microns-pore-size filter, the chemotactic migration rates of PMNs of patients were similar to those of controls. Evaluation of the data on an individual basis suggested that in terms of PMN chemotaxis some patients were hyperresponsive and some were hyporesponsive. Chemotaxis, spontaneous migration, and the rates of lipopolysaccharide-induced tumor necrosis factor alpha production by JP monocytes were similar to those of control cells. Our results give credence to the view that there are minor aberrations in the functions of JP phagocytes, but the extent to which these aberrations are relevant to accumulation of PMNs at sites of infection and inflammation in vivo and possibly contribute to the pathogenesis of JP remains unclear.

Spontaneous lymphocyte proliferation in severe periodontal disease: role of T and B cells

Spontaneous proliferation of T cells, B cells and unseparated lymphocytes was studied in patients with severe periodontal disease and control subjects. In the patient group only, spontaneous lymphocyte proliferation was reduced, whereas B cell proliferation was enhanced. The findings offer further support for the existence of a disturbance in immune regulation in patients with severe periodontal disease.

Increased periodontal bone loss in temporarily B lymphocyte-deficient rats

In order to study the role of T lymphocytes and B lymphocytes in the development of marginal periodontitis, experiments were performed on specific-pathogen-free (SPF) rats with various immunologic profiles. The study comprised nude (congenitally T lymphocyte-deficient), thymus-grafted nude (T-lymphocyte reconstituted), anti-mu treated (temporarily B lymphocyte-deficient), and normal rats. When they were 5 to 9 weeks old, some of the rats were inoculated with Actinomyces viscosus. Bacteroides gingivalis and a strain of oral spirochetes; 90 days later they were killed. A. viscosus and B. gingivalis colonized readily, but the spirochete strain could not be established permanently in the oral cavity of the rats, 95% of the inoculated rats raised serum IgG or IgM antibody against one or more of the microorganisms; nude rats tended to raise less antibody than the three other experimental groups. Inoculated rats had significantly less periodontal bone support than controls. Anti-mu treated inoculated rats had significantly less periodontal bone support than nude and normal rats, whereas no difference was found between normal, nude, and thymus-grafted rats. It is concluded that permanent T-lymphocyte deficiency did not interfere with the development of periodontal disease in this model, whereas a temporary and moderate reduction in B-lymphocyte numbers seemed to predispose for aggravation of periodontal bone loss.

Some immunological findings in adult periodontitis

There is little doubt that immunological mechanisms play an important role in chronic inflammatory periodontal disease. At the same time, it is recognized that patient susceptibility is ultimately responsible for the clinical manifestation of the disease. In this context, the present study was undertaken to examine a range of systemic immunological parameters in patients with adult periodontitis (AP), so as to test the hypothesis that a specific pattern would identify diseased--possibly 'at risk'--patients. These parameters included serum IgA, IgG, IgM, IgD, C3, transferrin, the presence of circulating immune complexes, and the number of circulating T (E-rosette forming) cells. One hundred and forty AP patients and 70 healthy controls were examined. Following a complex statistical analysis only the levels of IgG, IgM and IgD were significantly increased in adult periodontitis (p less than 0.05) while an increase in circulatory immune complexes was significant only for separate statistical tests. Although statistically different, the levels seen in AP patients were still within the normal range hence the clinical significance of the findings is such that it is unlikely that these systemic immunological parameters per se do define an 'at risk' population.

Serum levels of antibodies against Actinobacillus actinomycetemcomitans in various forms of human periodontitis

Serum levels of IgG, IgA, and IgM antibodies against extracts from Bacteroides gingivalis PER8, Actinobacillus actinomycetemcomitans Y4, and Bacteroides fragilis NCTC 9343 were determined in three categories of periodontitis patients by means of enzyme-linked immunosorbent assay. The test groups comprised 10 patients with juvenile periodontitis (JP), 18 young patients with severe periodontitis (YP), and 31 patients with adult periodontitis (AP). Nine subjects with healthy periodontium (HP) served as a reference group. Increased frequencies of patients with significantly elevated IgG and IgA antibody values against B. gingivalis and A. actinomycetemcomitans were found in the three periodontitis groups as compared with the HP group. The AP group, however, showed lower IgM values than the other groups. The results support the contention that A. actinomycetemcomitans may play a contributory role in adult periodontitis and that B. gingivalis is a suspected periopathogenic bacterium in juvenile periodontitis. The clinical YP classification was not supported by the present serologic findings.

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.

Abnormal lymphocyte profiles and leukotriene B4 status in a patient with Crohn's disease and severe periodontitis

THIS CASE REPORT DESCRIBES clinical and laboratory findings for a 60-year-old woman with recently diagnosed Crohn's disease and severe generalized periodontitis. Comparison of dental radiographs taken in 1975, in 1983, and at the time of our evaluation in 1986 revealed dramatic progression of alveolar bone loss over that period. Standard laboratory blood tests did not reveal any remarkable significant leukocyte abnormalities, but flow cytometric analysis of lymphocytes revealed a paucity of B cells stained with anti-light chain antibodies, and an increased proportion of T lymphocytes which were dully-stained with anti-CD5 monoclonal antibody. B cell function as determined by in vitro proliferative responsiveness to anti-IgM antibody was only about 50% of that observed with cells from two healthy normal subjects. Serum leukotriene B4 (LTB4) was elevated to 150% of normal values, in spite of the fact that the patient was taking a systemic anti-inflammatory drug which is known to reduce LTB4 levels. The microbial flora was highly mixed and included several putative periodontopathic bacteria. Therapy consisted of oral hygiene instruction, scaling and root planing, mucoperiosteal-flap curettage, extracoronal splinting, and selective extraction of three teeth. The periodontal status improved markedly with therapy. Possible relationships between the patient's immunological status, her Crohn's disease, and the severe periodontal breakdown are discussed.

Characterization and immunobiologic activities of lipopolysaccharides from periodontal bacteria

Bacterial surface structures play a critical role in the initiation of infectious diseases. Various surface components of pathogenic bacteria have been reported to be involved in host injury. There is a great deal of evidence incriminating certain Gram-negative, anaerobic bacteria present in the gingival crevice as etiologic agents of human periodontal diseases. We have isolated endotoxic cellular components from suspected periodontopathic bacteria and examined their immunobiological activities. Lipopolysaccharides (LPS) and lipid-associated proteoglycans (LPG) were prepared from whole cells by the phenol-water and butanol-water procedures, respectively. LPS from Bacteroides gingivalis, B. intermedius, B. oralis, and B. loescheii, Fusobacterium nucleatum and F. necrophorum, and Actinobacillus (Haemophilus) actinomycetemcomitans were found to possess biological activities comparable with those of LPS from E. coli K235 in terms of activation of Limulus lysate, B-cell mitogenicity, polyclonal B-cell activation, induction of bone resorption, and IL-1 production by macrophages. These LPS contained mainly sugars, amino sugars, and fatty acids. No heptose or 2-keto-3-deoxyoctonate (KDO) was detected in the Bacteroides LPS, while LPS from Actinobacillus and Fusobacterium species contained significant amounts of heptose as well as small quantities of KDO. Bacteroides LPS were clearly mitogenic for spleen cells of C3H/HeJ mice, which are non-responsive to LPS from E. coli, A. actinomycetemcomitans, and Fusobacterium species. Furthermore, polymyxin B was found to abrogate the mitogenic activity of LPS from E. coli, Actinobacillus, and Fusobacterium species, but not those from Bacteroides species. Spleen cells from both C3H/HeN and C3H/HeJ mice responded to all butanol-water-extracted LPG preparations, including those from E. coli, A. actinomycetemcomitans, and Fusobacterium species. It may be concluded that LPS and LPG isolated from suspected periodontopathic bacteria possess marked immunobiological potencies on lymphoreticular and bone cells.

In situ lymphocyte subpopulations from active versus stable periodontal sites

The purpose of this study was to evaluate lymphocyte subset densities and distributions within gingival biopsies from active sites (greater than or equal to 2 mm clinical attachment loss within three months of biopsy) versus clinically similar but stable or healthy sites. Small interproximal gingival biopsies representing at least one of each of the above categories were obtained from each of 20 periodontal maintenance patients. Serial cryostat sections displaying a cross section of the gingiva were labeled with monoclonal antibodies for (1) pan T cells, (2) T cytotoxic/suppressor cells, (3) T helper/inducer cells and (4) pan B cells and were developed using an avidin-biotin-peroxidase system. Lymphocyte populations were enumerated in repeatable fields from the sulcular, middle and oral one-third of each section. Relative proportions of the same lymphocyte subsets were analyzed in peripheral blood samples from the same patients using direct immunofluorescence. Pan B cells were significantly more prevalent in infiltrates from active sites than in stable (P less than 0.05) or healthy (P less than 0.01) sites. The T/B cell ratio was also significantly lower in active than stable biopsies (P less than 0.05), and in active biopsies versus blood (P less than 0.05). The T helper/T suppressor cell ratio did not vary significantly between blood and any gingival tissue disease group or location, but a trend toward lower relative numbers of T helper cells in the sulcular infiltrates of active sites was noted. These results support the premise that active periodontal sites display elevated B cell populations and abnormal immune regulation possibly involving the T helper cell subset.

Peripheral T lymphocyte subsets in rapidly progressive periodontitis

The peripheral blood lymphocyte subsets of 10 patients with rapidly progressive periodontitis were investigated with monoclonal antibody. In 4 patients, the T helper/T suppressor ratio was increased. 5 others had a slightly reduced T helper/T suppressor ratio as compared to control group. These findings may indicate a possible cellular immune response in the pathogenesis of rapidly progressive 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.

Immunologic dysfunction in the pathogenesis of periodontal diseases

Despite significant progress in our understanding of the pathogenesis and etiology of periodontal diseases, the nature and contribution of the immune system to this disorder remains unclear. Several studies provide evidence for either a protective or destructive rôle. These conflicting findings are difficult to reconcile, since most interpretations tend to argue for a static contributory rôle (i.e., either protective or destructive) of the immune system. Current theories on the rôle of the immune response do not address these conflicting findings as well as the contradictory observation of a detectable immune response in the face of persistent infection in these patients. In this article, we present a model, based on available data, for the contribution of the immune system to the pathogenesis of periodontal disease. This model ascribes a dynamic rôle for the immune response. As documented in other infectious diseases, it is entirely possible, for example, that a state of immunologic dysfunction may occur in the earliest stages of periodontal disease progression; this may then be followed by a period of active immune reactivity (humoral and/or cellular) that would represent either a delayed or depressed response. This model is discussed in conjunction with recent findings that several suspected periodontal pathogens are capable of producing immunosuppressive agents. Many of the apparently contradictory clinical observations concerning the host immune response to oral pathogens and its correlation (or lack of) with both the progression and severity of periodontal disease may be accounted for in this model.

Phenotypic analyses of mononuclear cells recovered from healthy and diseased human periodontal tissues

Mononuclear cells were recovered from the gingival tissues of normal individuals and from patients with periodontal disease. Lymphocyte phenotypic markers were identified by immunofluorescence after reaction with monoclonal antibodies to T-cell subset markers. The normal tissues exhibited T4/T8 ratios almost identical to those in the peripheral blood. The diseased tissue cell ratios were significantly reduced, in both the adult periodontitis and the juvenile periodontitis groups (P less than 0.01 and P less than 0.02, respectively), indicating alterations in the T-cell subset distribution in these tissues. Each diseased patient showed a much decreased T4/T8 ratio in the gingival lymphocytes when these were compared with the peripheral blood ratio from the same patient. The T4/T8 ratios of the more severe sites were significantly lower than those of the less severe sites in the same disease category. The decreases in subset ratios could be attributed to statistically significant reductions in T4+-lymphocyte recoveries relative to peripheral blood and also to slight relative increases in T8+ lymphocytes. A highly significant (P less than 0.001) correlation between the average probeable periodontal pocket depth and the T4/T8 ratio of each disease category was demonstrated. The relative recoveries of B cells from the various tissues did not differ between diseased and normal tissues. It is suggested that T-cell regulatory expression in gingival tissues is distinct from peripheral blood regulatory expression and that there is a local immunoregulatory imbalance in periodontal disease.

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.

The autologous mixed lymphocyte reaction (AMLR) as a possible indicator of immunoregulation in chronic inflammatory periodontal disease

Immunoregulatory control at both a local and systemic level is likely to be an important factor in the control of chronic inflammatory periodontal disease, explaining, at least in part, the individual variations between patients as well as the cyclical nature of the disease process. The autologous mixed lymphocyte reaction (AMLR), which is due to the stimulation of T cells by autologous HLA-DR positive non-T cells in the absence of specific antigen, is thought to be an in vitro correlate of immunoregulation. It is possible therefore, that the AMLR may detect systemic immunoregulatory phenomena in chronic inflammatory periodontal disease and that aberrations in the AMLR may be a manifestation of the disease and in turn reflect disease activity. Recent evidence does in fact suggest that the peripheral blood AMLR may identify particular disease groups, provided age and time of peak responsiveness are taken into account and hence may have an epidemiological application. It remains to be determined, however, that when used in a longitudinal fashion, the AMLR does reflect individual disease activity. These results are reviewed and areas of future research discussed.

Pathogenesis of periodontitis

Periodontitis is an inflammatory disease of the periodontium which is characterized by a progressive destruction of the tissues supporting the tooth. Its primary etiology is an ill-defined series of microbial infections which may be composed of only some of the more than 300 species of bacteria currently recognized in the oral cavity. The disease is currently considered to progress as periodic, relatively short episodes of rapid tissue destruction followed by some repair, and prolonged intervening periods of disease remission. Despite the apparent random distribution of episodes of disease activity, the resulting tissue breakdown exhibits a symmetrical pattern of alveolar bone loss and pocket formation which is common to several forms of periodontitis, although the distribution of the most affected teeth and surfaces may vary among diseases (e.g., juvenile periodontitis versus adult periodontitis or rapidly progressive periodontitis). Several reports have indicated that bacterial cells can be found in the pocket wall of periodontitis lesions. The translocation of bacteria into the tissues from the pocket environment is quite common, as evidenced by the common occurrence of bacteremias in patients with periodontitis following relatively minor events such as chewing and oral hygiene procedures. However, it is important to distinguish between the passive introduction of bacteria into periodontal tissues and frank invasion as might occur in an acute infection, since the pathological implications may be quite different.

Immunohistological identification of cell subsets in human gingiva after local treatment for gingivitis or periodontitis

The cellular infiltrate present in human diseased gingiva was analyzed in biopsies from 12 patients with gingivitis or periodontitis. The samples studied had been obtained in the course of surgery at inflammatory sites remaining after institution of periodontal treatment. Histological and immunological techniques were used to identify macrophages, B-cells, plasma-cells, T-cells and T cell subsets, as well as cells expressing class II HLA membrane antigens. T-cells appeared as the predominant population, but plasma-cells were also visualized in nearly all samples. Both OKT4+ and OKT8+ cells were seen in all cases, the latter being more numerous in periodontitis patients. Interdigitating-like cells were observed, positively labelled for class II antigens, as well as macrophages which were more numerous in periodontitis patients. These results suggest the participation of all components of the immune response in gingival disease, in a way resembling chronic recurrent inflammatory diseases.

Kinin generation in the gingival inflammatory response to topically applied bacterial lipopolysaccharides

A water-soluble lipopolysaccharide from Salmonella enteritidis and a phenol-soluble lipopolysaccharide from Leptotrichia buccalis were applied topically to the healthy marginal gingivae of beagle dogs. Saline was applied to contralateral areas as an internal control. Increases in vascular permeability were monitored by measurement of gingival fluid, and the collected gingival fluid samples were assayed for kininogenase and kinin activities. Both lipopolysaccharides induced an inflammatory response, as indicated by increased gingival fluid flow. Kininogenase-kinin activities paralleled the increases in gingival fluid flow, with the highest values being associated with peak increases in gingival fluid. The results indicate that both lipopolysaccharides, although different in lipid solubility, penetrate healthy sulcular epithelium and initiate an inflammatory response which is mediated in part by the kallikrein-kinin system. Interrelationships between this system and other inflammatory mediators suggest that kinin generation not only plays a role in the early phases of acute gingival inflammation, but may also contribute to the activation of other mediators appearing later in the response and in chronic inflammatory lesions.

Effect of age and periodontal disease status in man on the spontaneous proliferation of peripheral blood lymphocytes

Spontaneous lymphocyte proliferation (SLP), as a measure of the autologous mixed-lymphocyte reaction (AMLR), was used to detect possible systemic immunoregulatory differences between periodontally-diseased subjects and age-matched controls. Forty-four subjects formed four groups; young-healthy (YH), young-diseased (YD), old-healthy (OH) and old-diseased (OD) based on clinical examination to assess loss of attachment and bleeding on gentle probing. The mean loss of periodontal attachment for the YD, OH and OD groups was 5.9, 3.3 and 6.0 mm respectively, and the mean bleeding index was 0.39, 0.18 and 0.44. Their SLP was assessed using peripheral-blood mononuclear cells on days 3, 5, 7, 9 and 11 in culture. The peak response for the YH group occurred at day 7; that of the OH group was not until day 9, suggesting that age may alter the kinetics of the reaction as a delay in peak responsiveness. Using log transformation, to reduce individual variations within each group, SPL of peripheral-blood mononuclears from diseased subjects was depressed at day 7 for the young age group (p less than 0.01) and at day 9 for the older group (p less than 0.05). Not all diseased subjects had a depressed response, suggesting that SPL per se may reflect current rather than past disease activity. It seems that SPL could identify particular disease groups provided age and time of peak responsiveness are taken into account.

Bacterial profiles of subgingival plaques in periodontitis

In this report over 400 subgingival plaque samples taken from over 110 patients were examined microscopically and culturally for 30 bacterial parameters. The patients could be placed into six disease categories based upon clinical criteria. The bacterial profile of each clinical category was generally distinctive of that category. Periodontal patients who had been successfully treated and maintained had plaques that were populated by significantly higher proportions of Streptococcus sanguis, Actinomyces viscosus, A. odontolyticus and S. mutans and significantly lower proportions of B. gingivalis and spirochetes compared to the five untreated disease categories. The spirochetes were the overwhelming microbial type in the plaques of adult periodontitis (AP) patients, averaging about 45% of the microscopic count. The bacteriological results could not distinguish between ADA Type III and IV periodontitis, suggesting that the same type of infection was occurring in an active site in any AP patient. The patients designated as early onset periodontitis (EOP) differed from the other patients by their relative youth and by their significantly higher proportions of Bacteroides gingivalis and/or B. intermedius. Two types of EOP were recognized in which the most diseased variant was characterized by having an average of 49% spirochetes in the plaque. Four localized juvenile periodontitis (LJP) patients were notable in not having detectable A. actinomycetemcomitans. The data indicate that the various types of periodontitis, with the possible exception of LJP are specific anaerobic infections involving spirochetes and to a lesser extent B. gingivalis and B. intermedius.

The cellular host response in juvenile periodontitis. A review

The current knowledge on the cellular, host-response features in juvenile periodontitis (JP) has been reviewed. The chemotaxis of the polymorphonuclear leukocytes (PMNs), known to be defective in JP, is modulated by serum factors and bacteria. The interactions of the putative etiologic pathogen Actinobacillus actinomycetemcomitans (A.a.) and the enzyme lysozyme with PMNs modify the host defense. Data on the phagocytic capacity of the peripheral blood and gingival crevice PMNs in JP are still controversial. The monocytes exhibit similar alterations as PMNs in interaction with A.a., but the reports on defective monocyte chemotaxis are conflicting. Both bacterial challenge and genetic factors may regulate the lymphocyte response in JP.

The stimulation of human peripheral blood lymphocytes by oral bacteria: macrophage and T-cell dependence

Human peripheral blood mononuclear lymphocytes from individuals with moderate periodontitis were separated into purified subpopulations of T lymphocytes and B lymphocytes by rosetting with sheep red blood cells (E). All three lymphocyte subpopulations were compared for proliferative responses to cell walls from seven oral bacteria, phytohemagglutinin (PHA), pokeweed mitogen (PWM), lipopolysaccharide (LPS), and streptolysin-O (SLO). Mononuclear cells and a re-combined subpopulation consisting of four parts purified T lymphocytes and one part B lymphocytes responded significantly to all of the stimulants. Purified T lymphocytes by themselves responded significantly to PHA and PWM, but were unresponsive to oral bacteria and SLO; however, T lymphocytes cultured with 2% autologous macrophages responded significantly to all seven oral bacterial cell walls and to SLO, which indicates that T-cell responses to oral bacteria are macrophage-dependent. T-cell-depleted non-E-rosette-forming B cells by themselves were poorly responsive to all of the tested stimulants; however, the responses of these cells to oral bacteria, PWM, LPS, and SLO increased significantly in the presence of 10% mitomycin-C-treated T cells, demonstrating that B cell proliferation to these stimulants is T-cell-dependent.

Effect of periodontal therapy on spontaneous lymphocyte response and neutrophil chemotaxis in localized and generalized juvenile periodontitis patients

The etiology and pathogenesis of juvenile periodontitis may involve dysfunctions of the host response. In particular, the neutrophil and the lymphocyte have been implicated in the disease. The purpose of the present study was to examine the in vitro spontaneous lymphocyte response and neutrophil chemotaxis in populations of localized juvenile periodontitis (LJP) and generalized juvenile periodontitis (GJP) patients and age- and sex-matched healthy subjects (HS). These laboratory values were also evaluated immediately following and 1 year after periodontal therapy. The results show that spontaneous lymphocyte responses reflecting the autologous mixed lymphocyte reaction (AMLR) are depressed for GJP patients. The decreased AMLR in the GJP group appears to represent an abnormal T-cell function which may reflect activity of the periodontal lesion. LJP patients have an increased AMLR response, although it was not statistically significant. 1 year following active periodontal therapy, spontaneous lymphocyte responsiveness returned to normal in most GJP patients. The increased spontaneous lymphocyte responsiveness of LJP patients was not changed either immediately following active periodontal therapy or 1 year later. LJP and GJP patients exhibited a neutrophil chemotaxis defect when compared to cells from HS. This neutrophil defect was still observed 1 year following active therapy.

Immunoregulation in severe generalized periodontitis

Severe generalized periodontitis (SGP) is an inflammatory disease which leads to extensive alveolar bone loss in young adults. Peripheral blood lymphocytes from SGP patients have been previously reported to exhibit an in vitro hyperproliferative response when exposed to B cell mitogens derived from Staphylococcus aureus and Actinomyces viscosus. Therefore hyperresponsiveness to B-cell mitogens could be an important pathogenic factor in the susceptibility to and progression of SGP. We have tested whether the hyperproliferative response of lymphocytes from SGP patients was due to (i) a functional deficiency of suppressor T cells, or (ii) to numerical alterations of lymphocytes. Supernatant fluids from concanavalin A-stimulated T cells from 14 SGP patients and 14 normal subjects were compared for their ability to suppress the IgM synthesis of B-cell mitogen-stimulated mouse splenocytes. No significant differences were noted in suppressor T-cell function between control subjects and SGP patients. However, SGP patients had significantly higher lymphocyte counts than control subjects, and there was a positive correlation between high lymphocyte counts and high mitogen-stimulated proliferation. SGP patients also had higher lymphocyte:monocyte ratios than control subjects, suggesting that a defect in macrophage-mediated suppression might be involved in the hyperproliferation phenomenon. Our data do not support the hypothesis that a suppressor T-cell defect is the cause of mitogen-induced hyperproliferative responsiveness of peripheral blood lymphocytes from SGP patients. Rather, hyperproliferation may be due to an expansion of the lymphocyte pool which responds to mitogens, or/and a regulatory disturbance which arises because of altered lymphocyte:macrophage ratios.

Peptidoglycan from the potentially pathogenic oral bacterium Actinomyces viscosus is a B-cell mitogen

Cell walls and peptidoglycan from Actinomyces viscosus, strain M-100 were compared for their ability to act as mitogens with spleen cells from germ-free Fischer rats. The cell walls were prepared from trypticase soy broth grown whole cells using a French press, followed by two consecutive washes with 0.1 M tris-HCl buffer, pH 8.0, 1 M NaCl and distilled water. Peptidoglycan was prepared from cell walls by three consecutive formamide extractions at 165 degrees C. On a dry-weight basis, the peptidoglycan was a significantly-better mitogen than cell walls, suggesting that the peptidoglycan is the major mitogenic component of A. viscosus cell walls. Mononuclear spleen cells were separated on a Nylon-wool column into a non-adherent subpopulation enriched for T lymphocytes and a weakly-adherent, plunger-removable subpopulation enriched for B lymphocytes. The non-adherent T-cell subpopulation responded strongly to the T-cell mitogen PHA, but was unresponsive to both the peptidoglycan and cell walls from A. viscosus. In contrast, the weakly-adherent enriched B-cell subpopulation was less responsive to PHA, but was strongly stimulated by A. viscosus peptidoglycan and cell walls. These results indicate that peptidoglycan and cell walls from A. viscosus are B-cell mitogens.