Immunohistological analysis of gingival lymphocytes in adult periodontitis

Impact of the Oral Commensal Flora on Alveolar Bone Homeostasis

Homeostasis of healthy periodontal tissues is affected by innate and adaptive immunosurveillance mechanisms in response to the normal oral flora. Recent comparisons of germ-free (GF) and normal specific-pathogen-free (SPF) mice have revealed the impact of host immunosurveillance mechanisms in response to the normal oral flora on alveolar bone height. Prior reports that alveolar bone height is significantly less in normal SPF mice compared with their age- and strain-matched GF counterparts suggest that naturally occurring alveolar bone loss is a normal component of healthy periodontal tissue homeostasis. In this report, histomorphometric analyses confirmed increased alveolar bone loss and revealed increased numbers of TRAP+ osteoclastic cells lining the alveolar bone surface in SPF compared with GF mice. Increased numbers of RANKL+ cells and IL17+ cells in the periodontium of SPF mice demonstrate possible molecular mechanisms mediating the up-regulated osteoclastogenesis and alveolar bone loss in SPF mice compared with GF mice. Increased numbers of T-lymphocytic cells and T-helper cells in the junctional epithelium of SPF mice compared with GF mice suggest that the adaptive immune response contributes to physiologic alveolar bone loss in the healthy periodontium. This GF animal model study notably begins to elucidate the impact of host immunosurveillance mechanisms in response to the normal oral flora, mediating catabolic alveolar bone homeostasis in the healthy periodontium.

Evidence for a specific crevicular lymphocyte profile in aggressive periodontitis

BACKGROUND AND OBJECTIVE

It is undisputed that the periodontal pocket is a particular region of the host defense that is dominated by polymorphonuclear leukocytes. However, little is known about the lymphocytes in the crevice. It was the aim of this study to analyse the proportions of T cells (CD3+), T-helper cells (CD4+), T-suppressor cells (CD8+), and B cells (CD20+) in the crevice of patients with localized aggressive periodontitis (LAP), generalized aggressive periodontitis (GAP), and generalized chronic periodontitis (CP). The results were compared with those obtained from periodontally healthy controls.

MATERIAL AND METHODS

Crevicular cells were collected according to a previously described method. The lymphocyte subpopulations were analysed by using an indirect immunofluorescence method.

RESULTS

Significant differences were established between the test groups and the controls regarding the mean number of CD8+ lymphocytes (LAP > CP and controls; p < 0.05) and CD20+ lymphocytes (LAP/GAP > CP, p < 0.05 and LAP/GAP > controls; p < 0.001). Significant variations in the CD4+/CD8+ ratio were observed (LAP < controls and GAP < controls; p < 0.01), as well as a correlation between the number of T cells and the degree of inflammation.

CONCLUSION

In the present study, patients with LAP and patients with GAP were found to have increased numbers of crevicular T-suppressor/cytotoxic and B cells. This supports the hypothesis of a changed immune pathology in patients with aggressive periodontitis.

Level of neopterin, a marker of immune cell activation in gingival crevicular fluid, saliva, and urine in patients with aggressive periodontitis

BACKGROUND

Neopterin, a marker of cellular immune activation, is produced by human macrophages after induction by interferon gamma that is secreted by T lymphocytes. Neopterin concentrations in diverse body fluids have been reported to increase in parallel with bacteria in the clinical course of infections. Therefore, determination of neopterin in body fluids was thought to be useful for predicting the prognosis and diagnosis of aggressive forms of periodontal disease, in which the cell-mediated immune response plays an important role in immunopathogenesis. The aim of the present study was to observe the role of neopterin in the pathogenesis of aggressive periodontitis (AgP).

METHODS

Thirteen individuals who were systemically and periodontally healthy and 16 systemically healthy individuals diagnosed with AgP were recruited for this study. Mixed saliva and urine samples were collected from each subject. Gingival crevicular fluid (GCF) samples were obtained from 6 teeth with > or =5 mm probing depth (PD). After evaluation of GCF amount from paper strips, enzyme-linked immunosorbent assay (ELISA) was employed to determine the amount of neopterin in urine, saliva, and GCF.

RESULTS

The amount of neopterin in urine and saliva measured 235.77+/-405.31 micromol neopterin/mol creatinine and 9.85+/-7.66 nmol/l, respectively, for the AgP group and 225.45+/-100.72 micromol neopterin/mol creatinine and 5.25+/-5.76 nmol/l, respectively, for controls. The present data demonstrate that, while salivary neopterin levels were found to be significantly different between periodontitis and control subjects, there were non-significant differences in urine neopterin levels. The amount and concentration of neopterin in GCF measured was 18+/-12.75 nmol/l and 3.67+/-2.40 nmol/ml for the AgP group and 2.51+/-1.72 nmol/l and 3.88+/-4.50 nmol/ml for the control group. When total amounts of neopterin are taken into consideration, a significant difference between AgP and controls is shown; however, no significant difference in net concentration of neopterin was found between both groups.

CONCLUSIONS

This study is the first report to evaluate the involvement of neopterin in AgP and this might be considered of value in understanding periodontal disease mechanisms.

Lamina propria dendritic cells express activation markers and contact lymphocytes in chronic periodontitis

BACKGROUND

Dendritic cells are characterized by shape, structure, and membrane molecule expression; they contact T lymphocytes to present antigens and stimulate plasma cell differentiation in vitro. Dendritic cells are known to be present in healthy human gingiva and to be altered in HIV-associated periodontitis. Here, we address the phenotype, location, and intercellular relationships of dendritic cells in chronic periodontitis.

METHODS

Biopsies from patients with chronic periodontitis were analyzed by electron microscopy and indirect immunofluorescence for dendritic cells and lymphocyte markers.

RESULTS

Langerhans' cells were spread in oral epithelium but restricted to the basal layer in pocket epithelium; they did not usually express major histocompatibility complex (MHC)-II antigens nor contact lymphocytes. Dendritic cells were abundant in the lamina propria of pocket epithelium; they were MHC-II positive, admixed with CD4-positive and CD8-positive T lymphocytes, and, they expressed CD54, CD80, and CD86. Dendritic cells often contacted lymphocytes and were also located within plasma cell aggregates.

CONCLUSIONS

The data suggest that prerequisites for mounting a T cell-mediated immune response exist in chronic periodontitis, although this response is limited to the lamina propria. These results suggest that T-cell responses offer limited protection and can contribute to tissue damage during periodontal disease.

CD9 and HLA-DR expression by crevicular epithelial cells and polymorphonuclear neutrophils in periodontal disease

BACKGROUND, AIMS

The composition of gingival crevicular fluid (GCF) is likely to reflect inflammatory modifications that take place in the gingiva during periodontal diseases.

METHOD

In this study, GCF was collected at 3 different sites from 23 periodontal patients. The sites were assessed to be healthy, presenting gingivitis or periodontitis. 10 healthy individuals without any form of periodontal disease formed the control group and were sampled at one site each. The cell content of GCF was collected using Durapore Millipore strips, and 2 types of cells were studied: epithelial cells (EC) and polymorphonuclear neutrophils (PMN). The expression of CD9 and HLA-DR within or on the surface of these cells was studied in immunofluorescence on cytospin smears.

RESULTS

Both CD9 and HLA-DR expression on EC differed significantly from control subjects, and the latter decreased according to the severity of the pathology. None of the PMN found in controls expressed CD9 or HLA-DR. However, in periodontal patients, the expression of HLA-DR within PMNs was detectable and increased according to the severity of lesions. CD9 expression on PMNs also increased with inflammation.

CONCLUSION

This study shows that clinically healthy sites of periodontal patients already present signs of immunological activation characterised by a down modulation of HLA-DR expression on EC and an upregulation of these 2 molecules in PMN.

Osteoclastogenesis is enhanced by activated B cells but suppressed by activated CD8(+) T cells

Host immune response is known to contribute to the progression of periodontitis, and alveolar bone destruction in periodontitis is associated with enhanced osteoclast activity. Therefore, we evaluated the roles of activated lymphocyte subsets in osteoclastogenesis. Osteoclast precursors were co-cultured with activated lymphocytes (B, CD4(+) T, CD8(+) T) in the presence of either macrophage colony-stimulating factor (M-CSF) alone or M-CSF plus soluble receptor activator of NF-kappaB ligand (sRANKL), and subsequent differentiation into active osteoclasts was evaluated by a resorption assay. The activated B and CD4(+) cells, but not CD8(+) T cells, induced osteoclast differentiation in the presence of M-CSF alone. In the presence of M-CSF and sRANKL, B cells induced the formation of small but highly active osteoclasts and increased resorption, while CD8(+) T cells profoundly suppressed osteoclastogenesis. Co-culture using an insert well or supernatant suggested that both B and CD8(+) T cells acted on osteoclasts mostly via soluble proteins. Activated B cells expressed many osteoclastogenic factors including RANKL, TNF-alpha, IL-6, MIP-1alpha, and MCP-3. CD8(+) T cells expressed a substantial amount of osteoprotegerin (OPG) along with RANKL. However, blocking antibody to OPG did not reverse the suppression by CD8(+) T cells, suggesting that other factor(s) are involved. Taken together, activated B cells promoted osteoclastogenesis, while CD8(+) T cells inhibited the osteoclast formation via direct interaction. The results imply the importance of lymphocyte subpopulations in the development of periodontitis.

Herpesvirus infection of inflammatory cells in human periodontitis

Human cytomegalovirus (HCMV) and Epstein-Barr virus type 1 (EBV-1) are frequently detected in human periodontitis lesions. However, no information is available on the types of gingival cells infected by herpesviruses. The present study determined the presence of herpesviruses in polymorphonuclear neutrophils, monocytes, macrophages and T and B lymphocytes in biopsies of periodontitis lesions from 20 adults. A nested polymerase chain reaction method was employed to detect HCMV, EBV-1, EBV-2, human herpes virus-6 and herpes simplex virus (HSV) in periodontal tissue biopsy and in gingival cell fractions separated by immunomagnetic cell sorting. Tissue specimens from 18 (90%) and cell fractions from 14 (70%) patients demonstrated herpesviruses. Periodontitis-derived monocytes and macrophages revealed HCMV in cell fractions from 11 (55%) patients and HSV in cells from 1 (5%) patient. T lymphocytes harbored HCMV in cell fractions from 4 (20%) patients and HSV in cell fractions from 4 (20%) patients. B lymphocytes showed EBV-1 in cell fractions from 9 (45%) patients. Periodontal polymorphonuclear neutrophils demonstrated no herpesviruses. This study suggests that HCMV mainly infects periodontal monocytes, macrophages and less frequently T lymphocytes and that EBV-1 infects periodontal B lymphocytes. The possible etio-pathologic significance of periodontal herpesvirus infection is discussed.

Characterization of immunocompetent cells in the diseased canine periodontium

The beagle dog with naturally occurring periodontal disease is one of the most widely used animal models in periodontal research for histological studies on disease pathogenesis and on the effect of potential therapeutic regimens. However, previous studies were restricted to morphological assessment of immunocompetent cells because of the lack of available cell-specific markers. In this study we systematically characterized the specificity and immunoreactivity of a panel of anti-human antibodies for identification (ABC method) of immunocompetent cells in formalin-fixed, EDTA-decalcified, paraffin-embedded inflamed periodontal tissues obtained from six beagle dogs. Canine lymph nodes and a panel of different human tissues served as positive controls. Polyclonal anti-CD3 immunolabeled canine T-lymphocytes specifically. Anti-CD79alpha (clone HM57) reacted with B-lymphocytes and plasma cells, and CD79alpha (clone JCP117) showed no staining in canine tissues. Neutrophils, monocytes, small macrophages, and keratinocytes reacted with an anti-myeloid/histiocyte antibody (clone MAC387). Anti-CD68 (clones PG-M1 and EBM11) immunolabeled large macrophages and plasma cells. Clone EBM11 also stained osteoclasts and cementoclasts. With the exception of JCB117, all antibodies revealed similarly favorable immunolabeling of canine and human immunocompetent cells. Long-term EDTA decalcification appeared to weaken immunostaining of plasma cells with HM57. MAC387 and CD68 can be used to distinguish macrophages in different differentiation stages in canine periodontal tissues. (J Histochem Cytochem 46:1443-1454, 1998)

Local and systemic TCR V gene expression in advanced periodontal disease

The aim of the present investigation was to study the expression of specific alpha/beta T cell receptor (TCR) gene products in relation to some microbiological and immunological features of advanced destructive periodontitis. 21 individuals with advanced periodontal disease (diseased group) and 16 age- and sex-matched healthy subjects (healthy group) were recruited. Following a clinical examination of the diseased group, the 3 deepest interproximal sites in the upper and lower premolar- or molar segments (i.e., 12 sites in each individual) were selected for further analysis. Samples from the subgingival microbiota were obtained from the pocket of the selected sites and were prepared for a microbiological examination. The gingival tissue at one of the selected sites was also biopsied. Each excised soft tissue specimen was divided into 2 equal portions. One portion of the biopsy was prepared for histometric and morphometric analyses. The 2nd portion was snap frozen and prepared for immunohistochemical analysis. A sample of peripheral blood was obtained from each individual of the diseased and the healthy group and prepared for immunohistochemical analysis. The selected sites of the diseased group harbored varying numbers of microorganisms which have been associated with periodontal disease. The excised gingival tissue contained inflammatory lesions with substantial numbers of lymphocytes and plasma cells including T- and B-cells and a TCR V alpha/beta gene repertoire dominated by Vbeta 17. The TCR profile of the lesion, however, differed markedly from that of the circulating blood of the diseased subjects. While only minor differences were observed between the blood samples of the diseased and the healthy subjects regarding the TCR genes, CD5, HLA-DR and CD5+CD19 positive cells occurred in higher proportions in the blood samples of the subjects susceptible to periodontal disease than in healthy controls. It may be suggested that (i) TCR V alpha/Vbeta expression in peripheral blood samples of subjects with periodontal disease does not differ from that of healthy individuals, and (ii) the periodontitis lesion expresses a unique TCR repertoire in which the Vbeta 17 gene dominates.

Cell-mediated immune system regulation in periodontal diseases

The adaptive immune system consists of humoral and cell-mediated immunity. T-lymphocytes are the key components of cell-mediated immunity. CD4+ helper T-lymphocytes facilitate B-cells to differentiate and produce specific antibodies, whereas CD8+ cytotoxic T-lymphocytes kill virally infected cells. Periodontal diseases have been associated with a variety of imbalances in the regulation of immune responses. Changes in the ratios of peripheral blood CD4+ and CD8+ T-lymphocytes, depressed proliferative responses of peripheral blood lymphocytes, and increased frequency of CD45RO+ memory T-lymphocytes in diseased tissues have been reported in individuals with various forms of periodontal disease. While some studies have shown an increased frequency of gamma delta + T-cells in periodontal lesions, the role of gamma delta + T-cells in periodontal disease remains controversial. The ability of putative periodontopathic bacteria selectively to stimulate certain V beta-expressing T-cells is intriguing and could determine whether a CD4+ Th1 or a CD4+ Th2 cell response is elicited. The prominence of a particular subset of helper T-cells within the periodontal lesion could be a reflection of the stage and activity of the disease, or the types of bacteria present. Regardless, longitudinal studies of the involvement of T-cell subsets and cytokines in periodontal disease are clearly needed.

Immunomodulatory and superantigen activities of bacteria associated with adult periodontitis

Immune dysfunctions are frequently associated with chronic inflammatory diseases. Several investigators have reported that patients with severe periodontitis show reduced or negligible levels of proliferative responses of peripheral blood and gingival lymphocytes to periodontopathic organisms. The purpose of this study was to evaluate the influences of products from Porphyromonas gingivalis (P. gingivalis) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) on lymphocytes obtained from periodontally diseased and non-diseased individuals in order to extend our understanding of the possible role of such bacterial components as immune modulators. Pooled cultures of either P. gingivalis or A. actinomycetemcomitans were disrupted using glass beads in a bead mill to prepare whole cell homogenates. These homogenates were then co-cultured with human peripheral blood mononuclear cells (PBMC) and known lymphocyte stimulators. Cultures were pulsed with tritiated thymidine, harvested, and radio label incorporation was determined. Responses to toxic shock syndrome toxin-1 (TSST-1) and pokeweed mitogen (PWM) were inhibited at high concentrations of bacterial homogenate. However, as the concentration was reduced, responses induced by PWM were restored while TSST-1 induced responses remained inhibited. Such results suggest that P. gingivalis and A. actinomycetemcomitans contain potent immunosuppressants with differential influences on lymphocyte population. These effects on B- and T-cells are independent of periodontal disease status and appear to exert their influence through non-toxic mechanisms. In addition, work currently underway presently indicates that obligate oral anaerobic bacteria such as P. gingivalis produce substances with some of the characteristics of superantigens.

In situ localization of cell synthesis and proliferation in periodontitis gingiva and tonsillar tissue

OBJECTIVE

Previous work indicates that large numbers of B and T cells accumulate in the periodontal soft tissues although we know little about cellular synthetic activity and proliferation in this site. The aim of this study was to examine lymphocytic cell synthetic activity and proliferation in periodontitis gingiva and compare this to a known site of leucocyte proliferation, namely the oropharyngeal tonsils.

MATERIALS AND METHODS

Messenger RNA (mRNA) and 28S ribosomal (28S rRNA) expressing cells in formalin-fixed/paraffin-embedded gingival and tonsillar tissue sections were detected by in situ hybridisation (ISH) using poly-deoxyribothymidine and 28S probes respectively. In addition S-phase proliferating and cycling cells were also detected by ISH with histone probes and by Ki-67 immunohistochemistry. Ten gingival biopsy samples were obtained from adult periodontitis patients and five tonsillar biopsies from tonsillectomy patients.

RESULTS

Both mRNA and 28S rRNA-expressing cells were detected in all the samples tested. Plasma cells showed the strongest signal for the two probes and slight to moderate staining could be seen in epithelium, fibroblasts and endothelial cells. In contrast, gingival lymphocytes were either weakly stained or were unstained for these probes of synthetic activity. In tonsils, most lymphocytes in germinal centres showed moderate staining and mantol zone cells were much more weakly stained. In gingival samples, histone mRNA-expressing and cycling (Ki-67) cells were detected in 4/10, 10/10 cases respectively. These positive cells were mainly basal and suprabasal epithelial cells and a few mononuclear cells, whereas most germinal centre lymphocytes (B cells) were positive for this probe. The number of Ki67 positive cells was greater than histone mRNA bearing cells both in gingiva and tonsillar tissue. In contrast, mantol zone cells (mainly T cells) were sparsely stained by probes of cell proliferation.

CONCLUSION

These results indicate that local proliferation of B cells does not occur in periodontitis gingiva in contrast with tonsillar tissue, although plasma cells showed strong synthetic activity in both tissues. T cells did not appear to proliferate greatly nor undergo active synthesis in either of these tissues. These findings substantiate previous hypotheses that specific leucocytes predominate in the gingival tissue through selective homing rather than by local proliferation.

Immunohistological characteristics of periodontal lesions associated with Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans infections

In this study, various phenotypes of infiltrating cells in the periodontium adjacent to pockets harboring Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans were evaluated. Furthermore, the pattern of class II antigen expression in the periodontal tissues was determined. Eight lesions were associated with the presence of P. gingivalis and 12 with A. actinomycetemcomitans. Predominant cells in the inflammatory infiltrate were T- and B-cells. In most biopsies T-cells dominated over B-cells. The proportion of P. gingivalis, but not of A. actinomycetemcomitans, was positively correlated to the total number of infiltrating cells in the tissue. A. actinomycetemcomitans sites demonstrated somewhat lower proportions of CD3+, CD4+ and CD19+ cells than P. gingivalis sites. However, the tendency of decreasing CD4+/CD8+ ratio with increasing number of A. actinomycetemcomitans indicates a local imbalance in immunoregulation. The frequency of class II antigen expression of both mononuclear and epithelial cells, a sign of immunological activation, was generally high.

Some microbiological, histopathological and immunohistochemical characteristics of progressive periodontal disease

The aim of the present investigation was to study the local nature of human periodontal disease by assessing the microbiota and the composition of the tissue lesions at sites with progressive attachment loss in periodontitis susceptible subjects. 300 subjects with periodontal disease were monitored for 2 years without treatment. 8 subjects lost > 2 mm of attachment at > or = 3 sites during both the first and the second 12 month interval. These 8 subjects (progressive disease group; PD) were recalled for a microbiological and histopathological examination. A group of age- and sex-matched subjects were identified who during the 2 years of monitoring exhibited gingivitis and deep pockets, but no further attachment loss. This group of 11 subjects (non-progressive disease group; NPD) served as controls. From the 8 active disease subjects, > or = 1 interproximal site which had displayed disease activity (progressive disease active; PDA) and > or = 1 contralateral site without disease progression (progressive disease inactive; PDI) were sampled. From the 11 control subjects, 1 site/subject was sampled (NPD). The total number of viable micro-organisms (TVC) in the subgingival microbiota was estimated and a series of bacterial species were identified and enumerated. The gingival tissue of the sampling site was excised and the soft tissue prepared for morphometrical and immunohistochemical analyses. No differences were observed in the subgingival microbiota of the sample sites in the subjects who exhibited disease progression (PD) when compared with the subjects with periodontally diseased but stable conditions (NPD).(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of interleukin-1 (IL-1) mRNA-expressing macrophages in human inflamed gingiva and IL-1 activity in gingival crevicular fluid

The exact cell type and site(s) involved in interleukin-1 (IL-1) production during gingival inflammation was determined by combining immunohistochemistry and in situ hybridization. IL-1 messenger RNA (mRNA)-expressing cells in human inflamed gingiva were identified as macrophages. The rate of IL-alpha mRNA expression in these macrophages was the same as IL-1 beta mRNA expression. The rate of IL-1 mRNA expression was higher in connective tissue furthest from the pocket epithelium, although more macrophages were present at the connective tissue subjacent to the pocket epithelium. The IL-1 activity in gingival crevicular fluid (GCF) obtained from inflamed gingiva was higher than that from healthy gingiva and decreased after periodontal therapy. The IL-1 activity in GCF was almost completely abolished by the addition of anti-IL-1 alpha antibody but not by anti-IL-1 beta antibody, indicating that IL-1 alpha is the predominant form in GCF. However, the IL-1 activity in GCF was unrelated to the number of IL-1 mRNA-expressing macrophages in the same gingival site where the GCF was obtained at the same time. The results suggest that macrophages in the connective tissue subjacent to the oral epithelium contribute to the production of IL-1 but those in connective tissue subjacent to the pocket epithelium play a different role in the generation of gingival inflammation.

Distribution of natural killer cells in periodontal diseases: an immunohistochemical study

We studied the distribution and incidence of natural killer (NK) cells in gingiva affected with adult periodontitis (AP) and rapidly progressive periodontitis (RP) with immunohistochemical methods using antibodies Leu-7 and Leu-11b. The incidence of Leu-7 positive cells revealed no significant difference among mild AP, severe AP, and RP. On the other hand, Leu-11b positive cells were frequently found in severe AP and RP. The accumulation of NK cells reacting with Leu-11b in the infiltrated connective tissue was greater in severe forms of periodontal disease (severe AP and RP) than in mild AP. These results suggest that Leu-11b positive NK cells may play a role in the destruction of tissues in periodontal diseases.

Papillon-Lefevre syndrome. Characterization of peripheral blood and gingival lymphocytes with monoclonal antibodies

A 14-year-old boy with typical features of Papillon-Lefevre syndrome (PLS) is presented. The purpose of this report was to study the immunopheno-typic features of the peripheral blood and gingival tissue lymphocytes with monoclonal antibodies in the patient. Peripheral blood T-cells, helper-T cells, suppressor-T cells, HLA-DR+ cells and IL-2R+ cells were determined using appropriate monoclonal antibodies and indirect immunofluorescence methods. B-cells were identified using the direct immunofluorescence technique. The gingival tissue was processed for both histopathological and immunohistological examinations. Gingival tissue lymphocytes were identified using monoclonal and polyclonal antibodies with the immunoperoxidase technique. Although we have not detected any significant alterations in the peripheral blood B-cell and T-cell populations, NK cells were significantly increased. HLA-DR+ cells and IL-2R+ cells were within normal limits. Histopathology of the diseased tissue revealed predominance of plasma cells in the lamina propria. The majority of the plasma cells were bearing IgG isotype. Most of the CD3+ T-cells were located beneath the pocket epithelium with an almost equal distribution of CD4+ and CD8+ T-lymphocytes, in situ. These findings indicate that PLS is a IgG+ plasma cell dominated lesion with the participation of T-lymphocytes, having similar distributions of both subsets. While the etiopathogenesis of the syndrome still has to be elucidated, these immunohistological findings could be used for further studies in this intriguing entity.

Expression of interleukin-2 receptor and HLA-DR on lymphocyte subsets of gingival crevicular fluid in patients with periodontitis

Expression of interleukin-2 receptor (IL2R) and HLA-DR on lymphocytes of gingival crevicular fluid (GCF) was examined by two-color flow cytometric analysis. GCF from 15 patients with periodontitis was collected by crevicular washing. Mononuclear cells were isolated by Ficoll-paque gradient centrifugation from inflamed gingival tissue (GT) and peripheral blood (PB) sampled from each of the 15 patients. Lymphocyte subsets were detected by using monoclonal antibodies (mAb) of Leu 12 (CD19), Leu 4 (CD3), Leu 3a (CD4) and Leu 2a (CD8) directed to B cells, T cells, helper/inducer T cells (Th) and suppressor/cytotoxic T cells (Ts), respectively. Anti-IL2R (CD25) and anti-HLA-DR were used as lymphocyte activation markers. IL2R- or HLA-DR-positive fractions in Th, Ts and B cells were calculated. Percentage of IL2R-positive fraction in Th (IL2R+ Th) of GCF (34.0%) was significantly higher than those of GT (18.4%) and PB (13.7%). IL2R-positive fraction in B cells (IL2R+ B) of GCF was the highest among the three groups (23.9% in GCF, 12.5% in GT, 6.3% in PB). Ts did not express IL2R regardless of the origin of the samples. Compared with PB and GT, GCF showed significantly higher HLA-DR expression on Th and Ts in GCF (PB: 8.7% and 27.1%; GT: 27.9% and 50.3%; GCF: 44.7% and 65.3%). These results suggest that lymphocytes in GCF were highly activated and are related to the local host immune response in periodontitis.

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.