Langerhans cells (LCs) were first described by Paul Langerhans, in 1868, as dendritically shaped cells, which were located in the squamous epithelia of epidermis. Later on, these cells were identified in all stratified squamous epithelium of mammals. Dendritic cells (DCs) play an important role in local defense mechanisms in the epithelium. LCs are situated usually in the suprabasal layer of stratified squamous epithelia of oral mucosa and epidermis of skin. They constitute 3% of the cell population in epidermis. LCs are thought to act as antigen presenting cells (APCs) during initiation of immune responses. With the help of APCs, the lymphocytes are able to recognize and respond to specific microbes. In this paper we have reviewed the origin, distribution, demonstration and mechanism of action of LCs and their role in different pathological conditions.
Dendritic cells are arguably the most potent antigen-presenting cells and may be the only cells capable of initiating the adaptive immune response. The epithelial residents of dendritic cells are Langerhans cells, which serve as the “sentinels” of the mucosa, altering the immune system not only to pathogen entry but also of tolerance to self antigen and commensal microbes. Oral mucosal Langerhans cells are capable of engaging and internalizing a wide variety of pathogens and have been found responsive to nickel in patients with nickel allergies, oral Candida species, oral lichen planus, lichenoid drug eruptions, graft versus host diseases, periodontal diseases median rhomboid glossitis, human immunodeficiency virus infection, hairy leukoplakia of the tongue, and oral squamous cell carcinoma. Review focuses on the role of antigen-presenting cells in particular Langerhans cells to better understand the mechanisms underlying immune responses. In this review, comprehensive detail about mucosal diseases has been compiled using the PubMed database and through textbooks.
The present study was undertaken with an aim of determining the cytological features observed in mucosal smears of oral submucous fibrosis (OSF) patients and comparing them with that of features of normal mucosal cells. The observed features were than analyzed for their reliability in detecting malignant changes in this premalignant condition. Objective of the study was to conduct an oral exfoliative cytology (OEC) study on 30 clinically diagnosed cases of OSF and 30 cases of clinically normal mucosa with no other systemic disease. We observed that all the smears from clinically normal buccal mucosa showed Class I cytology. The exfoliated cells were of normal size and shape with normal staining intensity and normal nuclear characteristics. All the 30 cases of our study group showed features suggestive of benign atypical cytological changes (Class II cytology). In the present study, despite the small number of cases, cytological features consistently observed in all the cases, were indicative of a premalignant change and emphasized a regular follow-up of patients. Early detection of a premalignant oral lesion promises to improve the survival rate of patients suffering from these conditions.
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