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Biomedical subjects

M Jontell

Publications and source records attributed to M Jontell.

At least 55 records · Page 3Linked to original sources
PubMed1992

Accessory cells in the immune defense of the dental pulp.

This communication focuses on the participation of accessory cells in the initial recognition and processing of antigenic substances in the dental pulp. Immunohistochemical analyses have demonstrated the presence of two types of accessory cells--one with a dendritic morphology located in the periphery of the pulp and one with a macrophage-like appearance located more centrally. Functional studies in vitro have provided evidence for the dendritic cells being the most significant of the two cells regarding their capacity to induce T-cell proliferation. Studies on ontogeny have revealed that the appearance of pulp accessory cells is delayed compared to other peripheral tissues. In experimentally induced pulp lesions a rapid increase of cells with morphologic and phenotypic features similar to normally occurring accessory cells was found. These data demonstrate that the dental pulp contains the necessary cellular constituents to mount an immunologic defense reaction. Future studies should focus on elucidating possible interactions between these immune cells and the neurovascular system of the pulp.

Antigen-Presenting Cells↗
PubMed1991

Class II antigen expressing cells in experimentally induced pulpitis.

This study reports on the occurrence of class II antigen expressing cells in inflammatory lesions experimentally induced in the rat incisor pulp. Concanavalin A and lipopolysaccharide of Bacteroides gingivalis were applied to the exposed pulp following a preparation through alveolar bone and dental tissues in the midpart of the root. In a set of control teeth, pulpal exposures were capped with Cavit without the placement of antigenic material. Animals were killed after 3, 12, 24, 48 or 96 hours. Pulp tissue specimens were subjected to immunohistochemical analysis utilizing a monoclonal mouse anti-rat class II antigen antibody. Semi-quantitative assessment of positively stained cells was carried out under the light microscope. Significantly more class II antigen expressing cells were identified in the challenged pulps than in the controls at all experimental periods. The increase in cells peaked at 48 hours to taper off at the subsequent 96-hour observation. The rapid and intense influx of class II antigen expressing cells suggests that these cells are associated with the initial defence of the dental pulp.

Animals↗
PubMed1991

Ontogeny of class II antigen expressing cells in rat incisor pulp.

Class II antigen expressing cells are generally associated with the early phase of the immune response. Dendritic cells and macrophages expressing these cell surface antigens have recently been demonstrated and characterized in the dental pulp. The present study was undertaken to determine when the pulp receives its immunologic defense potential by examining the temporal appearance of class II antigen expressing cells in the rat incisor pulp. Pulp tissue specimens obtained at various time periods from a gestational age of 16 days to 14 wk after birth were examined by immunohistochemistry using O x 6 as a primary antibody and the ABC-technique. Comparisons were made with tissue samples from the spleen, intestine, skin and oral mucosa. At birth, all tissues, except for the pulp, presented cells expressing class II antigen with a dendritic appearance in a number and orientation resembling the mature tissue. A complete distribution of these cells was not seen in the dental pulp until 7 weeks following birth. Data show that the dental pulp acquires its ultimate structural arrangement of immune cells later than other tissues.

Animals↗
PubMed1990

Human papilloma virus in erosive oral lichen planus.

Several types of human papilloma viruses (HPV) have been associated with benign and malignant squamous cell tumours of mucosal epithelium. To identify HPV in erosive oral lichen planus (OLPe), considered as a premalignant lesion, tissues from 20 patients were examined by Southern blot hybridization with 32P-labeled HPV DNA probes. Type 11 was found in 6 of the lesions while HPV types 6, 16 and 18 were not detected in any of the tissues examined. Using a type-specific polymerase chain reaction (PCR) assay for HPV-6, 11, 16 and 18, HPV-11 was detected in 8 of the samples (all of those positive by Southern blot), and, in addition, HPV-6 was found in 5 samples and HPV-16 in 3 samples. Overall, by the more sensitive PCR assay, 65% of samples were positive for HPV DNA. The finding of HPV DNA in many of the samples using two different techniques indicates a high prevalence of HPV in the OLPe afflicted oral mucosa. However, the role of HPV in the pathogenesis of OLPe has yet to be determined.

Adult↗
PubMed1989

Phenotypic characterization of mononuclear cells and class II antigen expression in angular cheilitis infected by Candida albicans or Staphylococcus aureus.

In the present study we characterized the phenotypes of infiltrating mononuclear cells in angular cheilitis lesions to further explore the pathogenesis of this disorder. Frozen sections from lesions infected by Candida albicans and/or Staphylococcus aureus were subjected to immunohistochemical analysis utilizing monoclonal antibodies directed to subsets of T-lymphocytes, B-lymphocytes, and macrophages. In addition, the expression of Class II antigens (HLA-DP, -DQ, -DR), the interleukin 2- and transferrin-receptors was studied on resident and infiltrating cells. An intense infiltration of T-lymphocytes was accompanied by expression of Class II antigens on the epidermal keratinocytes in lesion infected by Candida albicans. The Staphylococcus aureus infected lesions displayed a diffuse infiltration of T-lymphocytes but virtually no expression of Class II antigen by epidermal keratinocytes. These observations suggest that the cell-mediated arm of the immune system is involved in the inflammatory reaction of lesions infected by Candida albicans. In addition, the present study confirms that epidermal expression of Class II antigens is closely related to the type and magnitude of the infiltrating T-lymphocyte. Finally, these findings indicate that the type of inflammatory reaction in angular cheilitis is primarily dependent on the isolated microorganism, although the clinical pictures of the disorder are virtually identical.

Adult↗
PubMed1989

Epidermal Langerhans' cells in chronic eczematous dermatitis of the palms treated with PUVA and UVB.

Epidermal Langerhans' cells (LC) were studied in patients with chronic eczematous dermatitis of the palms. The monoclonal antibodies anti-Leu 6 and anti-HLA-DR were used, and the cells visualized with an immunoperoxidase technique. Increased numbers of LC were found in allergic contact dermatitis as well as in irritant contact dermatitis and hyperkeratotic dermatitis of the palms. The increased number of epidermal LC in lesional skin may facilitate presentation of exogenous or endogenous antigens to activated T-cells. One hand was treated with PUVA or UVB and the other hand served as a non-exposed control. PUVA treatment cleared the dermatitis and the LC number decreased markedly. With UVB treatment clinical improvement was achieved, and a less pronounced decrease in epidermal LC was noticed. There seems to be a crude relationship between the extent of clinical improvement and the reduction in epidermal LC numbers. The change in LC might be a primary event or secondary to a reduction of the inflammatory process.

Adult↗
PubMed1988

Normal human peritoneal macrophages are unable to cap and internalize class II antigens.

Normal human peritoneal macrophages show a restricted capacity to differentiate into inflammatory macrophages in vivo. We now report that these cells are unable to cap and internalize HLA-DR, as compared to endometriosis, and other macrophages. Immunoelectron microscopy indicated that lack of modulation was not due to the presence of preclustered antigenic sites. Northern blot analysis demonstrated transcripts for HLA.DR, c-fms, and c-fos, indicating that the surface defects were not likely to be associated with a general depression of transcriptional activity. There was no correlation between the mobility of class II molecules and the ability to present antigen as determined by autologous lymphocyte responses to tetanus toxoid. The inability of normal peritoneal macrophages to modulate class II antigens may represent a normal and more general environmental alteration required to permit peritoneal cells a scavenging function without developing the deleterious effects leading to a peritoneal inflammatory response.

Antibodies, Monoclonal↗
PubMed1988

Class II antigen expression of epidermal Langerhans cells in renal allograft recipients.

This study was designed to investigate the influence of systemic immunosuppressive therapy on the HLA-DR expression of epidermal Langerhans cells. Fifteen renal allograft recipients immunosuppressed with cyclosporin A and steroids were studied. Skin biopsies were taken from the upper arm prior to transplantation and at different intervals during the post-transplantation period. The epidermis was separated from the dermis, and the epidermal sheet was subjected to immunohistochemistry in order to make the HLA-DR antigens on the Langerhans cells visible. Following 2 days of immunosuppression, the number of Langerhans cells expressing HLA-DR antigens started to decrease and after 1 week, only 60% of the initial number of positive cells were detected. The number of positive cells remained low throughout the experimental period. It is suggested that systemic immunosuppressive therapy will suppress the expression of HLA-DR antigens on epidermal Langerhans cells, something which may mirror a systemic effect on other antigen-presenting cells.

Adolescent↗
PubMed1988

Recurrence of angular cheilitis.

The incidence of recurrence of angular cheilitis following a successful antimicrobial treatment was studied in 48 patients. Clinical assessments including a microbial examination were carried out 8 months and 5 yr after termination of treatment. Eighty percent of the patients reported recurrence of their angular cheilitis on one or more occasions during the observation period. Patients with cutaneous disorders associated with dry skin or intraoral leukoplakia had an increased incidence of recrudescence. Neither the presence of denture stomatitis nor the type of microorganisms isolated from the original lesions of angular cheilitis, i.e. Candida albicans and/or Staphylococcus aureus, were associated with the number of recurrences. The present observations indicate that treatment of the majority of patients with angular cheilitis should be considered in a longer perspective than previously supposed, due to the short lasting therapeutic effects of the antimicrobial therapy.

Adult↗
PubMed1988

Dendritic cells and macrophages expressing class II antigens in the normal rat incisor pulp.

This study has identified and characterized class II (Ia) antigen-expressing cells in the normal rat incisor pulp by immunohistochemistry and flow cytometry. Two types of Ia-expressing cells occurred: one with a pronounced dendritic appearance located primarily in the periphery of the pulp, and one with morphological characteristics similar to those of macrophages. The latter cells were mainly observed in the central portion of the pulp. A numerical ratio of 1:4 was established between the two cell types. The existence of Ia-expressing cells suggests an inherent capacity of the pulp to process and present foreign antigens.

Animals↗
PubMed1988

Treatment of angular cheilitis. The significance of microbial analysis, antimicrobial treatment, and interfering factors.

This prospective study evaluated the significance of microbial analysis and antimicrobial treatment for the cure of angular cheilitis. Furthermore, various etiologic factors were investigated for their relative effect on the healing process. The study included 1) an open trial with 50 patients infected by Candida albicans and/or Staphylococcus aureus, and 2) an intraindividual comparison of eight patients with bilateral lesions infected by Candida albicans as the only detected pathogen. After a base-line examination the patients received ointments containing nystatin and/or fusidic acid, on the basis of the outcome of an initial microbial analysis. The patients were evaluated clinically, photographed, and examined for microorganisms at different time intervals. Ninety-six per cent of the patients who participated in the open trial had no sign of infection after 42 days of treatment. Lesions in the double-blind study, treated with nystatin, were healed after 28 days, whereas lesions that received placebo persisted throughout the treatment period. Increasing age, dry skin, and extended skinfolds at the corner of the mouth were factors closely related to the length of the healing process.

Adult↗
PubMed1988

Epidermal Langerhans' cells in patients with pustulosis palmoplantaris treated with etretinate or etretinate + methoxsalen photochemotherapy.

Epidermal Langerhans' cells (LC) were studied in patients with pustulosis palmoplantaris (PPP) by utilizing the monoclonal antibodies anti-Leu6 and anti-HLA-DR in combination with an immunoperoxidase technique. In non-pustular areas of the skin lesions in PPP, an increased number of epidermal LC was found compared with control subjects. No change in LC counts was observed following etretinate monotherapy for 2 weeks. Etretinate was then combined with PUVA treatment of one palm/sole with the contralateral side as a non-UVA exposed control. After 6-12 weeks of etretinate + PUVA treatment the PPP had resolved and the number of epidermal dendritic HLA-DR+ and Leu6+ cells had normalized. On the contralateral side, etretinate treatment induced a marked clinical improvement and a reduction of HLA-DR+ cells. The observation of an increased LC population in active PPP and a reduction during clinical improvement indicates a close relationship between LC and the activity of PPP.

Adult↗
PubMed1987

Immunocompetent cells in the normal dental pulp.

The existence and location of various immunocompetent cells in the human dental pulp were investigated. Pulp tissue for analysis was obtained both from clinically intact pre-molars and from third molars without restorations or caries. Frozen and acetone-fixed pulp tissue sections were subjected to indirect immunohistochemistry with monoclonal antibodies to the following cell types: all peripheral T cells, helper/inducer T cells, cytotoxic/suppressor T cells, macrophages, B cells, and Class II antigen-expressing cells. Dendritic cells expressing Class II antigens (HLA-DR, -DQ), indicating a capacity for presentation of antigen to T helper cells, were seen in the odontoblastic layer as well as in the central portions of the pulp tissue. T lymphocytes, divided into helper/inducer and cytotoxic/suppressor cells, were observed in all pulp specimens. B cells were not seen in any of the pulp samples examined. The data demonstrate that the human dental pulp is equipped with immunocompetent cells essential for the initiation of immunological responses.

Adolescent↗
PubMed1987

HLA-DR3 antigens in erosive oral lichen planus, cutaneous lichen planus, and lichenoid reactions.

HLA antigens were examined in patients with erosive oral lichen planus (OLPe), cutaneous lichen planus (CLP), or lichenoid reactions (LR) adjacent to amalgam fillings. The control group had amalgam restorations in contact with the oral mucosa but without any reactions. A strong association was found between HLA-DR3 and OLPe, with an RR value of 21.0 (p less than 0.05). The corresponding values for CLP and LR were 2.3 and 1.5, respectively (NS). The haplotype A1-B8-DR3 was more frequently found in OLPe (p less than 0.05) and CLP (p less than 0.05) than in LR and controls (NS). The data indicate that OLPe, CLP, and LR, which present with virtually the same histopathologic features, are different in their association with HLA-DR3. Moreover, the increased frequency of HLA-DR3 in OLPe suggests an autoimmune component in the pathogenesis of this disorder.

Adult↗
PubMed1986

Mast cells in oral lichen planus.

Biopsies from lichen planus affected oral mucosa were compared with biopsies from healthy oral mucosa, in terms of the number of mast cells, their location and their morphological alteration at the light microscopic and electron microscopic level. In comparison with the normal oral mucosa an increased number of mast cells was found below the subepithelial infiltrate. This difference was statistically highly significant (p less than 0.001). In the deeper part of the infiltrate mast cells were found to contain granules which presented an altered morphology upon electron microscopic examination. These cells had many of the ultrastructural changes that have been reported for mast cells undergoing degranulation. The present morphological observations suggest that mast cells participate in the recruitment of lymphocytes to the subepithelial infiltrate.

Adult↗
PubMed1986

Expression of Class II transplantation antigens by epithelial cells in oral candidosis, oral lichen planus and gingivitis.

Biopsies from normal oral mucosa and oral mucosa affected by candidosis, lichen planus or gingivitis were compared with respect to the expression of two Class II transplantation antigens, HLA-DR and HLA-DQ, by epithelial cells and the relationship of these antigens to the distribution and frequency of T-lymphocytes. Indirect immunohistochemistry with different mouse monoclonal antibodies was used on frozen and acetone-fixed sections. To evaluate the results, a score system based upon the expression of the Class II transplantation antigens by epithelial cells and the frequency of T-lymphocytes was used. In oral candidosis there was a marked expression of HLA-DR antigens throughout the epithelium. In addition, this type of epithelium was the only one that expressed HLA-DQ antigens. An intense intraepithelial infiltration of T-lymphocytes was observed. Oral lichen planus and gingivitis did, to a much lesser extent, cause the expression HLA-DR antigens by the epithelial cells. In both lesions, the number of T-lymphocytes within the epithelium did not exceed the number found in epithelium of normal mucosa. In these types of lesions, the subepithelial infiltrate varied in intensity but was mainly composed of T-lymphocytes reactive with anti-Leu 3a antibodies. The results of the present study imply that epithelial expression of the two different Class II antigens are related to the frequency of the T-lymphocytes and to the proximity of these cells to the epithelial cells.

Adult↗