|DENTAL SCIENCE - ORIGINAL ARTICLE
|Year : 2014 | Volume
| Issue : 5 | Page : 146-149
Langerhans cells in lichen planus and lichenoid mucositis an immunohistochemical study
M Devi1, TR Saraswathi2, K Ranganathan2, D Vijayalakshmi1, C Sreeja1, S Shabana Fathima1
1 Department of Oral and Maxillofacial Pathology, Adiparasakthi Dental College, Melmaruvathur, Chennai, Tamil Nadu, India
2 Department of Oral and Maxillofacial Pathology, Ragas Dental College, Uthandi, Tamil Nadu, India
|Date of Submission||30-Mar-2014|
|Date of Decision||30-Mar-2014|
|Date of Acceptance||09-Apr-2014|
|Date of Web Publication||25-Jul-2014|
Dr. M Devi
Department of Oral and Maxillofacial Pathology, Adiparasakthi Dental College, Melmaruvathur, Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Aim: The aim of this study is to identify and evaluate Langerhans cell (LC) in lichen planus (LP), lichenoid mucositis (LM) and normal mucosa (NM) using CD1a monoclonal antibody immunohistochemically. Materials and Methods: A total of 15 cases of oral lichen planus and 15 cases of LM were selected based on clinical examination and confirmed by histopathological analysis. The biopsies from the 10 patients were taken from normal buccal mucosa as control. Paraffin blocks of tissue were made, which are used for routine hematoxylin and eosin staining and immunohistochemical staining using biotin streptavidin methods (CD1a monoclonal antibody). Analysis of CD1a expression was performed by evaluating the labeling index (LI) for each slide. Results: The mean CD1a LI for LP was significantly higher than that of LM and NM in the basal and supra basal layer. The mean CD1a positive cells in the connective tissues for LP were higher than that of LM and NM. Conclusion: This study clearly demonstrates a statistically significant increase in number of LC in LP than in LM, indicating the possible different immunopathogenic mechanisms.
Keywords: Langerhans cell, lichen planus, lichenoid mucositis
|How to cite this article:|
Devi M, Saraswathi T R, Ranganathan K, Vijayalakshmi D, Sreeja C, Fathima S S. Langerhans cells in lichen planus and lichenoid mucositis an immunohistochemical study. J Pharm Bioall Sci 2014;6, Suppl S1:146-9
|How to cite this URL:|
Devi M, Saraswathi T R, Ranganathan K, Vijayalakshmi D, Sreeja C, Fathima S S. Langerhans cells in lichen planus and lichenoid mucositis an immunohistochemical study. J Pharm Bioall Sci [serial online] 2014 [cited 2019 Nov 16];6, Suppl S1:146-9. Available from: http://www.jpbsonline.org/text.asp?2014/6/5/146/137427
Lichen planus (LP) is a chronic mucocutaneous disease due to a cell mediated immunological response to an antigenic change in the skin or mucosa. 
Lesions that appear clinically identical to LP, but caused by drugs are called lichenoid drug eruption (LDE). LDE involving the oral mucous membrane is also termed as lichenoid mucositis (LM). It occurs after the administration of systemic drugs such as NSAID, sulfonyl ureas, antimalarials, betablockers, angiotensin-converting enzyme inhibitors, diuretics, gold salts, and heavy metals.  Clinical and histopathological features of LM and LP are similar in many respects.
In oral LP, it has been hypothesized that the initiation of the disease process is triggered by the permeation of unknown antigens from the oral cavity into the oral epithelium.  The passage of antigens through the epithelium is by the entrapment of these antigens by Langerhans cells (LC). LC is immunocompetent dendritic cells that form a network within the epithelium. They process antigens for presentation to CD4 helper/inducer T lymphocytes, which in turn will activate CD8 suppressor/cytotoxic T lymphocytes. These CD8 cells are responsible for the basal cell degeneration seen in LP.  In LM associated with systemic drug administration, the mode of access of the antigen to the immune system is unlikely to be directly across the epithelium.  It probably involves a more remote site of antigen processing and presentation in the epithelium without the involvement of LC. This explains the less LC counts in LM when compared to LP and this is due to different modes of antigen processing and presentation.  With this background, we did this study to compare the clinical and histopathological features of LP and LM and to evaluate the number and activity of LC, by using monoclonal antibody CD1a, to determine the possible different immunopathogenic mechanisms of these lesions.
| Materials and Methods|| |
A total of 15 cases of oral lichen planus (OLP) and 15 cases of LM were selected. Detailed case history including age, and sex, occupation, past medical history and dental history with history of habits, drugs, and trauma were recorded. This is followed by general examination and intraoral examination.
Clinically, appearing bilateral white lesion having the characteristic Wickham's striae with or without dermatological manifestation was considered as LP. As the clinical features of LP and LM are similar, white lesions with bilateral distribution were categorized as LP and those with unilateral distribution as LM clinically. Informed consent was taken from all cases of OLP and LM prior to the biopsy procedure. However, the final diagnosis was based on histopathological features.
Biopsies from the 10 patients were taken from normal buccal mucosa adjacent to the site of surgery during the surgical removal of third molar as control. All the patients were in good general health and none of them had taken anti-microbial or anti-inflammatory drugs within the previous 3 months.
After adequate fixation paraffin blocks of tissue were made. From the blocks, 5-micron thick sections were cut and used for routine hematoxylin and eosin staining and immunohistochemical staining using biotin streptavidin methods (CD1a monoclonal antibody). Analysis of CD1a expression was done by evaluating the positive cells. CD1a positive cell showed staining pattern as membranous and weakly cytoplasmic (as recommended by product specification) [Figure 1] and [Figure 2].
|Figure 2: Photomicrograph of CD1a expression in lichenoid mucositis (×10)|
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Analysis of CD1a expression by evaluating the labeling index (LI) for each slide was calculated by dividing the number of positive cells by the total number of cells counted in the slide and expressed as percentage. A total of 1000 cells were counted in each slide.
| Results|| |
Data entry and analysis were performed using SPSS version 10.0.5 ® (SPSS Statistics is a software package used for statistical analysis. Long produced by SPSS Inc., it was acquired by IBM in 2009. SPSS 10.0.5 was released in December 1999). Mean LI and standard deviation were calculated to assess CD1a expression. Analysis of variance was done to compare the mean LI of CD1a between LP, LM and normal mucosa (NM). Bonferroni test of multiple comparison test was done to compare the LI of CD1a between LP, LM, and NM. The difference in mean LI between the study groups for basal layer, suprabasal layer was statistically significant (P = 0.00). The difference in mean positive cells between the study groups for connective tissue layer was statistically significant (P = 0.00) [Table 1] and [Figure 3] and [Figure 4]. The mean difference in Mean LI in basal layer of LP and LM was 2.96 and it was statistically significant (P = 0.001); in LP and NM was 5.54 and it was statistically significant (P = 0.00); in LM and NM was 1.49 and it was statistically not significant (P = 0.21).
|Figure 3: CD1a antibody mean LI in basal and supra basal epithelial layer|
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|Figure 4: CD1a antibody mean positive cells of connective tissue between the study groups|
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The mean difference in mean LI in supra basal layer of LP and LM was 2.82 and it was statistically significant (P = 0.016); in LP and NM was 5.55 and it was statistically significant (P = 0.000); LM and NM was 2.73 and it was statistically significant (P = 0.043).
The mean difference in mean LI in connective tissue layer of LP and LM was 44.67, and it was statistically significant (P = 0.000); in LP and NM was 57.37, and it was statistically significant (P = 0.00); in LM and NM was 12.70, and it was statistically not significant (P = 0.815) [Table 2].
|Table 2: Mean difference in CD1a antibody mean LI between the study groups|
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| Discussion|| |
Lichen planus represents a cell mediated immunological response to an induced antigenic change in skin or mucosa.  A wide variety of drugs have been associated with precipitating LP like eruptions and this phenomenon has been termed as LDE. Though individual drugs may be involved, multiple systemic drug therapy, topical agents and contact allergens may also be involved, perhaps by a synergistic action on the host immune system and precipitates LDE. These LDE occurring in oral mucosa are termed as LM. 
Because LM can resemble LP clinically and histopathologically, it is not always possible to conclude that a drug has induced LP or LM. Furthermore, the identification of the offending drug can be complicated by the factors such as simultaneous exposure to several drugs, drug interactions and variability in the latent period between intake of the drug and appearance of the eruptions. 
Langerhans cell plays a major role in the pathogenesis of LP as it recognizes, processes and presents the antigen to both helper and cytotoxic T cells specific for protein antigens, haptens, and alloantigens.  These dendritic cells initiate immune reactions, and the lesions of LP are characterized by sub- and intra-epithelial accumulation of T lymphocytes associated with basal cell destruction. 
To identify human LC in the epithelium, the most reliable marker used is CD1a (T6) antibody.  We have used this antibody to evaluate LC number and activity in LP, LM, and NM. We have considered those cells showing membranous and weakly cytoplasmic staining pattern as CD1a positive LC cells.
We observed that the mean CD1a LI for LP was significantly higher than that of LM and NM in the basal and supra basal layer. The mean CD1a positive cells in the connective tissues for LP were higher than that of LM and NM. The difference in mean LI among the study groups showed statistical significance. These observations were consistent with that of McCartan and Lamey,  Regezi et al.,  Laine et al.,  who reported statistically significant higher number of LC in LP. However they did not observe significant difference of CD1a LI between the different layers of the epithelium of LP.
Eversole  and Farthing et al.  observed dendritic cells in both the epithelium and the underlying connective tissue, involved in antigen processing and presentation to CD4 helper lymphocytes in LP.
Langerhans cell in OLP has been shown to be either increased in number or activated indicating the preparation for boosted antigen presentation.  Absolute numbers of LC in normal and diseased tissues are difficult to establish because the number of LC vary from one oral focus to another and from one patient to another.  Not all the results are comparable as a variety of staining techniques and counting techniques have been employed: Including counting per mm of basal layer, counting per mm of epithelial surface, per mm 2 of epithelium and per high power field direct counts and counts from photomicrographs. 
Regezi et al. postulated that although, there was an actual influx of additional LC into the epithelium in active state of LP, it could be argued that this may be more apparent than real. Increased metabolic activity and antigenic challenge could account for greater production of human leukocyte antigen-DR antigen expression in resident LC without real influx of LC. In our study, there was a significant difference in the mean difference CD1a LI between LP and LM in basal, supra basal layers of epithelium and in the connective tissue.
McCartan and Lamey  concluded that in OLP the initiation of the process appears to be permeation of antigens into the oral epithelium followed by the entrapment of the trans-epithelial antigen by LC. In LM associated with systemic drug administration, the route of access of the antigen to the immune system is unlikely to be directly across the epithelium but probably involves a remote site of antigen processing and presentation, which would be expected to result in reduced number of LC in the oral epithelium. In our study also our findings indicated decreased number of LC in LM than LP, as established by mean CD1a LI. The reduced LC count in LM as compared with LP argues for two different routes of antigen presentation and processing. 
In our study, we evaluated the mean difference in mean CD1a LI between LM and NM. The mean difference was higher in LM than NM and this difference was significant only in suprabasal layer than in basal or connective tissue layer. This observation can be explained as stated by McCartan and Lamey  that when LM occurred in response to topical agents and contact allergens, the route of antigen would probably be across the epithelium in which case the number of activated LC might be expected to equal those found in LP. 
| Conclusion|| |
A total of 40 patients were included in our study, comprising of 15 patients of LP, 15 LM and 10 NM. Immunohistochemical study was done to evaluate the number of LC in LP, LM, and NM. Increased number of LC was observed in LP, in the basal and supra basal layer of epithelium and in the connective tissue compared with LM and NM by using CD1a staining. This study clearly demonstrates a statistically significant increase in number of LC in LP than in LM, indicating the possible different immunopathogenic mechanisms.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]