The ultrastructure of human gingival Langerhans cells in health and disease

There was a statistically significant shift towards increased proportions of type I Langerhans cells (containing many Langerhans-cell granules) and reduced proportions of both type II Langerhans cells (containing few granules) and indeterminate cells in diseased oral epithelium when compared to healthy oral epithelium. Langerhans cells and indeterminate cells were also seen in the sulcular epithelium of healthy and diseased specimens but never in junctional or pocket-lining epithelium.     

Distribution of ICAM-1, LFA-3 and HLA-DR in healthy and diseased gingival tissues

Cell adhesion molecules are involved in recognition and effector aspects of the host response, including the control of migration of leukocytes into inflammatory sites. In this study we have demonstrated that the distribution of three cell-surface molecules involved in cell interactions, ICAM-1, LFA-3 and HLA-DR is distinct and different in healthy and diseased gingival tissue. ICAM-1 was consistently expressed by junctional epithelial cells in healthy gingiva and by pocket epithelium in diseased gingiva but was not detectable on the majority of keratinocytes in external gingival epithelium. ICAM-1 was also expressed by endothelial cells of gingival blood vessels and a subset of leukocytes in the infiltrated connective tissue in both healthy and diseased gingiva. HLA-DR and LFA-3 were also expressed by epithelial cells and endothelial cells but in patterns which were distinctly different from ICAM-1.     

Increasing expression of tissue plasminogen activator and plasminogen activator inhibitor type 2 in dog gingival tissues with progressive inflammation

Urokinase and tissue-type plasminogen activators (u--PA and t--PA) are serine proteases that convert plasminogen into plasmin, which degrades matrix proteins and activates metalloproteinases. The PAs are balanced by specific inhibitors (PAI--1 and PAI--2). Local production of t--PA and PAI--2 was recently demonstrated in human gingival tissues. The aim now was to investigate the production and localization of t--PA and PAI--2 in gingival tissues from dogs in three well-defined periodontal conditions; clinically healthy gingiva, chronic gingivitis and an initial stage of ligature-induced loss of attachment. At the start of the experiment the gingiva showed clear signs of inflammation. Clinically healthy gingiva were obtained after 21 days period of intense oral hygiene. Attachment loss was induced by placing rubber ligatures around the neck of some teeth. Biopsies were taken from areas representing the different conditions and prepared for in situ hybridization and immunohistochemistry. In clinically healthy gingiva both t--PA mRNA and antigen were expressed in a thin outer layer of the sulcular and junctional epithelia. No t--PA signals or staining were seen in connective tissue. Both mRNA signaling and immunostaining for t--PA were stronger in chronic gingivitis. In areas with loss of attachment, t--PA mRNA as well as antigen were found in the sulcular and junctional epithelia to a similar degree as in gingivitis. Occasionally the connective tissue was involved, especially in connection with vessels. PAI--2 mRNA was seen in a thin outer layer of the sulcular and junctional epithelia in clinically healthy gingiva, but no signals were seen in connective tissue. PAI--2 antigen was found primarily in the outer layer of the sulcular and junctional epithelia. Some cells in the connective tissue were stained. In gingivitis, PAI--2 signals were mainly found in the same locations, but more intense and extending towards the connective tissue. Immunostaining was seen in the outer half of the sulcular and junctional epithelia as well as in the upper part of the connective tissue, close to the sulcular epithelium. In sites with loss of attachment, PAI--2 mRNA was found throughout the sulcular and junctional epithelia, as was the antigen, which stained intensely. No PAI--2 mRNA was seen in connective tissue; the antigen was found scattered, especially near vessels. This study shows that the expression of both t--PA and PAI--2 increases with experimental gingival inflammation in the dog, and furthermore, the two techniques demonstrate a strong correlation between the topographical distribution of the site of protein synthesis and the tissue location of the antigens for both t--PA and PAI--2. The distribution correlates well with previous findings in humans.     

Gingival keratinocytes express HLA-DR antigens in chronic gingivitis

The expression of the histocompatibility antigens HLA-DR and HLA-A, B, C within periodontally diseased tissue was investigated using immunohistological and histochemical techniques. Tissue was obtained from 18 patients with periodontal disease and from 2 healthy volunteers. HLA-DR antigen was expressed by the keratinocytes of the oral epithelium in all inflamed samples but was not a feature of normal tissue where HLA-DR reactivity was confined to Langerhans cells. These results are consistent with an underlying cellular immune process. Using a variety of phenotypic markers it was possible to characterize the macrophage population within the connective tissue into 2 distinct types: an antigen-presenting cell type located subjacent to the oral epithelium and a phagocytic cell type situated deep within the connective tissue.     

Gingival keratinocytes express HLA-DR antigens in chronic gingivitis

The expression of the histocompatibility antigens HLA-DR and HLA-A, B, C within periodontally diseased tissue was investigated using immunohistological and histochemical techniques. Tissue was obtained from 18 patients with periodontal disease and from 2 healthy volunteers. HLA-DR antigen was expressed by the keratinocytes of the oral epithelium in all inflamed samples but was not a feature of normal tissue where HLA-DR reactivity was confined to Langerhans cells. These results are consistent with an underlying cellular immune process. Using a variety of phenotypic markers it was possible to characterize the macrophage population within the connective tissue into 2 distinct types: an antigen-presenting cell type located subjacent to the oral epithelium and a phagocytic cell type situated deep within the connective tissue.     

Oral mucosal Langerhans cells express DR and DQ antigens

The expression of the Class II antigens HLA-DR and HLA-DQ in human oral mucosa was examined in health and in the presence of inflammation. DQ antigens were detected on dendritic intra-epithelial cells which expressed the Langerhans cells (LC) phenotype T6+, DR+. In healthy gingiva, DR and DQ were co-expressed on Langerhans cells, whereas in an experimental gingivitis (day 8), more LC expressed DR than DQ. Absolute LC numbers were increased in inflammation. Traumatic ulceration of the buccal mucosa resulted in a decrease in the density of T6-, DR-, and DQ-positive cells. Repopulation of migrating and regenerated epithelium was complete 10 days after ulcer induction. Disparity between DR and DQ expression was seen in both normal buccal mucosa and throughout the ulcer healing period. These results are in agreement with the reported sequence of Class II antigen expression on lymphoid cells.     

Macrophages and lymphocyte subpopulations in nifedipine- and cyclosporin A-associated human gingival overgrowth

BACKGROUND: Nifedipine and cyclosporin A (CsA) induce gingival overgrowth. Both drugs have immunomodulating effects. It has been suggested that altered immune response is associated with drug-induced gingival overgrowth. In this study, we evaluated whether there were differences in macrophages and lymphocyte subpopulations in human nifedipine- and CsA-associated gingival overgrowth as compared with those in normal gingiva. METHODS: Biopsy samples of overgrown gingiva were obtained from 9 nifedipine-treated cardiac outpatients, 13 CsA-treated renal transplant recipients including 9 patients who were also receiving nifedipine, and 30 healthy control individuals undergoing dental treatment. Serial 5 microm thick cryostat sections were stained with mAbs for CD20 (B-pan), CD68 (macrophages), CD4 (T-helper/inducer), and CD8 (T-cytotoxic/suppressor) using an avidin-biotin-horseradish peroxidase complex method. Numbers of mAb-labeled and all nucleated cells were determined in 3 areas: the connective tissue beneath the sulcular epithelium, the middle connective tissue, and the connective tissue beneath the oral epithelium. Distributions of each type of cell were expressed as percentages of mAb-labeled cells in relation to total number of nucleated cells in a counting zone. Significances of differences between groups were tested by means of the Kruskal-Wallis test, and between pairs of results by means of the Mann-Whitney U-test. RESULTS: The proportion of CD8-labeled cells was significantly higher in connective tissue beneath the sulcular epithelium in the nifedipine group than in the controls (P = 0.014). In both medicated groups, the proportions of CD68-labeled cells were higher in all counting zones than in the controls, but statistically significantly only in the nifedipine group in the connective tissue beneath the oral epithelium (P = 0.008). No intergroup differences were found with respect to CD4- and CD20-labeled cells. The CD4/CD8 ratio was significantly lower in connective tissue beneath the sulcular epithelium in the nifedipine group than in the controls (P= 0.013). CONCLUSION: The results support the idea that immune response may be altered in drug-induced gingival overgrowth.     

Density of CD1a-labeled Langerhans' cells in normal human gingiva and in nifedipine- and immunosuppressive medication-induced gingival overgrowth.

BACKGROUND: The purpose of this study was to compare the distribution of Langerhans' cells in normal human gingiva and in nifedipine- and immunosuppressive medication-induced gingival overgrowth by means of an immunohistochemical study. METHODS: Gingival samples were collected from 11 nifedipine-medicated cardiac patients, 22 triple-medicated (azathioprine, prednisolone, and cyclosporin A) renal transplant recipients, and 28 generally healthy individuals. Patients were grouped into the immunosuppression group, the combined immunosuppression and nifedipine group, the nifedipine group, and the generally healthy control group. Five microm-thick cryostat sections were stained with monoclonal antibody (mAb) for CD1a using an avidin-biotin-enzyme complex (ABC) method. Numbers of CD1a-labeled cells/mm2 were determined in 6 areas: oral epithelium, oral sulcular epithelium, sulcular epithelium, middle connective tissue, connective tissue beneath the oral epithelium, and connective tissue beneath the sulcular epithelium. Significances of differences between the groups were tested by means of the Kruskall-Wallis test, and significances of differences between pairs of results by the Mann-Whitney U-test and the t test. RESULTS: Numbers of CD1a-labeled cells were significantly lower in the medicated groups than in controls in all 3 epithelial areas (P <0.0001) and in the connective tissue beneath the sulcular epithelium (P <0.0021). There were significantly fewer CD1a-labeled cells in the sulcular epithelium in the nifedipine group than in the other medication groups. CONCLUSIONS: The reduced numbers of CD1a-labeled cells found in nifedipine-induced gingival overgrowth were similar to the reduced numbers of CD1a-labeled cells in gingival overgrowth associated with immunosuppressive medication.     

Reduced numbers of Langerhans cells and increased HLA-DR expression in keratinocytes in the oral gingival epithelium of HIV-infected patients with periodontitis

BACKGROUND: HIV-seropositive (HIV+) patients become increasingly susceptible to periodontal diseases as HIV infection proceeds. We have previously shown that HIV+ patients with chronic marginal periodontitis (CMP) have remarkably increased numbers of gingival plasma cells in the connective tissue underlying the oral gingival epithelium, but depressed specific serum IgG levels towards periodontopathogenic bacteria. Langerhans cells (LC) and keratinocytes (KC) are antigen-presenting cells that are important in promoting immune responses. METHOD: In this study we examined, by means of immunofluorescence, the distribution and numbers of LC and activated KC in biopsies taken from inflamed periodontal sites in HIV+ and HIV patients with CMP. RESULTS: In the pocket epithelium in both patient groups, basal layer KC expressed HLA-DR molecules. In the oral gingival epithelium of HIV+ patients, basal layer KC also expressed HLA-DR molecules and numbers of LC were decreased as compared with HIV persons. CONCLUSION: The findings suggest that the oral gingiva in HIV+ patients may be affected by inflammation.     

Mitotic activity of keratinocytes in nifedipine- and immunosuppressive medication-induced gingival overgrowth

BACKGROUND: The purpose of the study was to compare mitotic activity in the basal cell layer of normal human gingiva and in nifedipine- and immunosuppressive medication-induced gingival overgrowth. METHODS: Gingival samples were collected from 19 generally healthy individuals, 12 nifedipine-medicated cardiac patients, and 22 immunosuppression-medicated (azathioprine, prednisolone, and cyclosporin A) organ transplant recipients. The transplant recipients were divided into those not taking nifedipine and those taking nifedipine. Cryostat sections were stained with monoclonal antibody for Ki-67, using an avidin-biotin-enzyme complex method. The mitotic activities of epithelial cells were determined as percentages of Ki-67 labeled cells in relation to total numbers of epithelial cells in the basal layer of oral, oral sulcular, and sulcular epithelium. RESULTS: Mitotic activities were significantly higher in all 3 medication groups in the oral epithelium (P < or =0.003), and in the immunosuppression group in the sulcular epithelium (P= 0.032) than in the controls. In the oral sulcular epithelium, mitotic activity was fairly similar in all medication groups. In the nifedipine group a significant negative correlation was found between duration of nifedipine medication and the percentage of Ki-67 labeled cells in the oral epithelium (P= 0.025). CONCLUSIONS: The results suggest that the increased epithelial thickness observed in nifedipine- and cyclosporin A-induced gingival overgrowth is associated with increased mitotic activity, especially in the oral epithelium.     

Pattern of distribution of T lymphocytes, Langerhans cells and HLA-DR bearing cells in normal human oral mucosa

The tissue distribution of helper/inducer and suppressor/cytotoxic T cells, Langerhans cells (LC) and HLA-DR bearing cells was determined in normal oral mucosa by use of monoclonal antibodies OKT4, OKT8, OK.T6 and OKIal, respectively. OKT4+ and OKT8+ cells were invariably present in normal oral epithelium and in the lamina propria. OKT8+ cells were consistently seen inside the basal cell layer of the epithelium. The distribution of LC in oral epithelium showed regional variation. In palatal epithelium LC were evenly distributed in the basal half of the epithelium, whereas in buccal mucosa the highest concentration of LC was seen in the epithelium overlying the tips of connective tissue papillae. OKIal stained dendritic cells in the epithelium and plump cells with small dendritic processes in the connective tissue. Some of the latter were located close to the basal cells of the epithelium. The consistent relationship between immunocompetent cells and the epithelium of the oral mucosa suggests the presence of a local immunologic defence barrier in the oral mucosa.     

Pattern of distribution of T lymphocytes, Langerhans cells and HLA-DR bearing cells in normal human oral mucosa

The tissue distribution of helper/inducer and suppressor/cytotoxic T cells, Langerhans cells (LC) and HLA-DR bearing cells was determined in normal oral mucosa by use of monoclonal antibodies OKT4, OKT8, OKT6 and OKIa1, respectively. OKT4+ and OKT8+ cells were invariably present in normal oral epithelium and in the lamina propria. OKT8+ cells were consistently seen inside the basal cell layer of the epithelium. The distribution of LC in oral epithelium showed regional variation. In palatal epithelium LC were evenly distributed in the basal half of the epithelium, whereas in buccal mucosa the highest concentration of LC was seen in the epithelium overlying the tips of connective tissue papillae. OKIa1 stained dendritic cells in the epithelium and plump cells with small dendritic processes in the connective tissue. Some of the latter were located close to the basal cells of the epithelium. The consistent relationship between immunocompetent cells and the epithelium of the oral mucosa suggests the presence of a local immunologic defence barrier in the oral mucosa.     

Distribution of carcinoembryonic antigen‐related cellular adhesion molecules in human gingiva

Carcinoembryonic antigen‐related cellular adhesion molecules (CEACAMs) are glycoproteins produced in epithelial, endothelial, lymphoid, and myeloid cells. Carcinoembryonic antigen‐related cellular adhesion molecules mediate cell–cell contact and host–pathogen interactions. The aims of this study were to map the distribution and examine the regulation of CEACAMs in human gingival sites. Quantitative real‐time PCR performed on human gingival biopsies from periodontitis sites revealed mRNA coding for CEACAM1, ‐5, ‐6, and ‐7. Immunohistochemistry showed that CEACAMs were not found in oral gingival epithelium, except for CEACAM5 in periodontitis. Carcinoembryonic antigen‐related cellular adhesion molecules 1, 5, and 6 were present in the oral sulcular epithelium of periodontitis but not in that of healthy gingiva. In junctional epithelium, all three molecules were present in healthy gingiva, but in periodontitis only CEACAM1 and ‐6 were detected. Staining for CEACAM1 and ‐6 was also seen in the inflammatory cell infiltrate in periodontitis. No staining for CEACAM7 was found. Proinflammatory mediators, including lipopolysaccharide (LPS), tumour necrosis factor‐α (TNF‐α)/interleukin‐1β (IL‐1β), and interferon‐γ (IFN‐γ), increased the expression of CEACAM1 and CEACAM6 mRNAs in cultured human oral keratinocytes. CEACAM1 and CEACAM6 mRNAs were also strongly up‐regulated upon stimulation with lysophosphatidic acid. In conclusion, the distribution of different CEACAMs was related to specific sites in the gingiva. This might reflect different functional roles in this tissue.     

Quantitative immunohistochemical analysis of keratins and desmoplakins in human gingiva and peri-implant mucosa.

Quantitative immunohistochemistry was used to compare the distributions of keratins and desmoplakins in human gingiva and peri-implant mucosa (three specimens each). In gingiva, keratin 1 (a marker of cornification) and desmoplakins I & II (markers of desmosomes) stained most heavily in granular strata followed by corneal strata; keratin 13, a marker of non-cornifying stratified squamous cells, stained most heavily in suprabasal strata of oral sulcular epithelium. Keratin 19, a marker for junctional epithelium, stained the basal stratum of oral sulcular epithelium most heavily. In peri-implant mucosa, the patterns of staining were similar, except that staining for desmoplakins I & II was generally significantly reduced compared with gingiva, and junctional epithelium co-expressed keratins 13 and 19. Peri-implant junctional epithelial cells attached to titanium implant abutments were removed by trypsin/EDTA digestion, and also exhibited co-expression of keratins 13 and 19. Inflammatory cell infiltration was associated with reduction of keratin 1 staining in gingiva. The data indicate that the epithelia of gingiva and peri-implant mucosa are not composed of identical cell populations.     

T cells and T-cell subsets in periodontal diseases

Acetone-fixed cryostat gingival tissue sections from marginal gingivitis (MG), juvenile periodontitis (JP), adult periodontitis (AP) patients and clinically healthy subjects (H) were immunohistochemically stained with monoclonal antibodies to aid in identification and quantification of T cells and T-cell subsets in the inflammatory infiltrates. T cells were present in all specimens studied. The number of T cells in the connective tissue (CT) zone of AP was much greater than in any other groups. The amounts of T cells in oral epithelium and sulcular (pocket) epithelium zones of diseased groups were larger than in the healthy group. There was a significant positive correlation between the number of T cells and the percentage of infiltrated connective tissue. While there were no significant differences between the mean ratios of T-helper/T-suppressor cells from diseased and healthy tissues, large individual variance existed in the three diseased groups. The existence of a high or low T4/T8 ratio in inflamed gingiva might be related to an abnormal immunoregulation.     

Disturbances of gingival fibroblast population homeostasis due to experimentally induced inflammation in the Cynomolgus monkey (Macaca fascicularis): potential mechanism of disease progression

We have studied the relationship between perturbations of fibroblast turnover in inflamed gingiva of different severities. To perform detailed spatial analyses of gingival fibroblast progenitor cells, inflammatory cell infiltrates and blood vessels, 3 Cynomolgus monkeys with healthy periodontium and 2 with naturally occurring gingivitis and ligature-induced periodontitis were pulse-labeled with ³H-thymidine. Morphometric analyses of radioautographs from mid-sagittal supra-alveolar gingival connective tissues of incisors were performed in sites subjacent to junctional, sulcular and oral epithelium, in the body of the lamina propria and just superior to the alveolar crest. The percentage of fibroblasts incorporating ³H-thymidine label, expressed as the labeling index (LI), was higher subjacent to the sulcular epithelium in periodontitis (1.73±0.37) than in healthy sites (1.06±0.22). This was not statistically significant (0.05 < p < 0.1) due to the small number of animals used. The sites subjacent to the sulcular epithelium also exhibited the largest increase in lymphocyte density from health to gingivitis (p < 0.01). In contrast, the LI of fibroblasts subjacent to the oral epithelium was 5-fold higher in healthy (0.82±0.17) compared to periodontitis sites (0.13 ± 0.09; p < 0.05). Labeled fibroblasts were found close to blood vessels in all compartments and in all disease states; distance to blood vessels was reduced in inflamed sites (p < 0.10). There were increased numbers of blood vessels per unit area in the lamina propria of gingivitis compared to healthy sites. However, there were no regional differences with respect to blood vessel numbers or area in sites subjacent to junctional epithelium with different disease states. The results indicate that: 1) experimentally-induced inflammation in the gingiva of Cynomolgus monkeys is associated with site-specific perturbations of cell turnover; 2) fibroblast progenitors are preferentially situated adjacent to blood vessels as in the periodontal ligament; 3) the vascular response to inflammation is a generalized increase in blood vessel numbers, but not their size; 4) reactive proliferation of fibroblasts may compensate for cell death in the lamina propria but is not detectable at the site of connective tissue attachment loss subjacent to the junctional epithelium. Failure to maintain the fibroblast progenitor population may be an important component of attachment loss in progressive periodontitis lesions.     

Macrophage subpopulations in gingival overgrowth induced by nifedipine and immunosuppressive medication

BACKGROUND: The immunomodulating effects of both immunosuppressive and nifedipine medication have been associated with drug-induced gingival overgrowth. The aim of the study reported here was to evaluate the presence of macrophage subpopulations in normal human gingiva and in gingival overgrowth induced by nifedipine and immunosuppressive medication. METHODS: Gingival samples were taken from 11 nifedipine-medicated cardiac outpatients (nifedipine group), 11 triple-medicated organ-transplant recipients also taking nifedipine (immunosuppression plus nifedipine group), 12 triple-medicated organ-transplant recipients (immunosuppression group), and 20 generally healthy individuals (control group). Cryostat sections were stained with mAbs for inflammatory 27E10, reparative RM3/1, and resident 25F9 macrophages using an avidin-biotin enzyme complex method. Total numbers of mAb-labeled cells were determined in connective tissue beneath sulcular epithelium, connective tissue beneath oral epithelium, and middle connective tissue. Expression of 27E10 was determined in keratinocytes in the oral epithelium. Statistics analyses were undertaken using the chi-square test, the Mann-Whitney U test, the independent samples t test, analysis of variance, and analysis of covariance. RESULTS: Greater numbers of inflammatory 27E10-positive macrophages were found in all 3 medicated groups and counting zones than in the control group except in connective tissue beneath sulcular epithelium in the immunosuppression group. The incidence of specimens expressing 27E10 antigen throughout the oral epithelium was significantly higher in the immunosuppression group (8 of 12) than in the control group (4 of 20) and the nifedipine group (2 of 11). Numbers of reparative RM3/1-positive macrophages were significantly greater in the immunosuppression group in connective tissue beneath oral epithelium than in the control group. The effect was markedly associated with degree of inflammation. Numbers of resident 25F9-positive macrophages were lower in connective tissue beneath sulcular epithelium in the immunosuppression group, and higher in middle connective tissue in the nifedipine group than in the control group. CONCLUSION: Our results show that the nature of drug-induced gingival overgrowth differs somewhat between immunosuppressive and nifedipine medications.     

The presence of bacteria in the oral epithelium in periodontal disease. III. Correlation with Langerhans cells

Langerhans cells (LC) are cell types found in the skin and gingiva. LC have immunological functions as phagocytic cells and as antigen-presenting cells for T and B lymphocytes. Sections from biopsies of the gingiva in cases of periodontal disease were found to have increased numbers of LC. These biopsies also contained intragingival bacteria. Serial sections of frozen specimens of human gingiva were prepared for staining. Hematoxylin and eosin were used for tissue survey, the Gram stain for assessment of bacterial invasion, anti-Leu-6 monoclonal antibody associated with peroxidase technique (PAP) to identify LC, antibacterial sera to Bacteroides gingivalis and Actinobacillus actinomycetemcomitans associated with peroxidase to specifically identify these two common periodontopathogenic bacteria. Additional positive identification of bacteria was performed by preparing the same histological section containing gram-stained particles for scanning electron microscope and transmission electron microscope LC confirmation. The results suggest that the increased number of LC seen in diseased sites of oral epithelium containing intragingival microorganisms may be one of the host immune mechanisms to penetration by bacteria.     

The ultrastructure of clinically normal sulcular tissues in the beagle dog

The ultrastructure of clinically normal beagle sulcular epithelium and underlying connective tissue has been studied in order to obtain base line information for comparison with similar studies of overtly inflamed gingiva. Normal sulcular epithelium in the beagle was observed to undergo a cytodifferentiation from typical keralinocytes of the stratum basale and stratum spinosum to flattened superficial cells which contained a relatively prominent endoplasmic reticulum and Golgi system. These cells also contained many dense granules of an unknown function. Narrow intercellular spaces filled with a material of moderate electron density were observed between flattened superficial cells. Moderate numbers of neutrophils were found in the epithelium along with "clear cells" of an unknown type.
The underlying connective tissue was characterized by a preponderance of well organized collagen libers and numerous fibroblasts. No unusual findings were noted in either blood vessels or peripheral nerves. Macrophages were prominently located in the lamina propria and in perivascular locations. Lymphocytes, neutrophils and plasma cells were seen in moderate numbers, usually located in the lamina propria portion of the sulcular wall. These cells when present in moderate numbers do not appreciably alter the integrity of the tissues and should be considered as components of a normal defense system.     

Patterns of cytokeratin expression in the epithelia of inflamed human gingiva and periodontal pockets

Fourteen specimens of periodontal pockets and the associated marginal gingiva were collected and either frozen for examination using antibodies against various defined cytokeratin specificities or processed for 2-dimensional gel electrophoresis. The epithelium forming the pocket lining typically extended into the connective tissue of the pocket wall in the form of a network of finger-like strips. Immunocytological staining indicated that keratins (K) 5, 6, 14 and 19 were expressed by almost all cells of the pocket lining and K13 and K16 by the suprabasal cells. The coronal region of the pocket lining showed some cells staining for K4, Staining for K8 and K18 was seen in the apieal region of the pocket lining and in the finger-like extensions of epithelium into the connective tissue. Compared with normal gingiva, the sulcular and the oral gingival epithelia showed a marked increase in staining for K19. Surprisingly, the pattern of keratin expression of the epithelium of the pocket lining was found to be essentially similar to that of normal junctional epithelium and the anatomical position of the boundaries between each epithelial phenotype were not significantly altered. These patterns of keratin expression were confirmed by the 2D electrophoretic analyses of microdissected regions of epithelium. The potential significance of inflammation to the epithelial changes associated with pocket formation is discussed.