The role of Langerhans cells in oral squamous cell carcinoma

Abstract

During the initiation, promotion, and progression of multi-step carcinogenesis, changes in specific host immunological factors have been observed. Although immunology of oral cancer has long been focused on antigens and lymphocytes, the fact remains that the antigen presenting cells, like the Langerhans cells (LCs) of the epithelium are initiators and modulators of the immune response. LCs as sentinels of immune response, have been investigated in several oral mucosal diseases, including cancer. Inadequate presentation of tumor antigens by host dendritic cells is one potential mechanism that allows tumor progression. In this review, the role of LCs in OSCC is discussed. Elucidation of the role of APCs, in particular LCs, may help to better understand the mechanisms underlying anti-tumour immune responses and, improve the effectiveness of anti-cancer immunity in tumour-bearing hosts. This section focuses on the roles LCs in the immunity of cancer and how cancer bypasses the dendritic cell-mediated immune responses, are discussed. Subsequently, the effects of tumor microenviornment on LC's and their therapeutic implications are elaborated.

A decreased peritumoral CD1a+ cell number predicts a worse prognosis in oral squamous cell carcinoma

“…Several researchers have been investigating the distribution of LCs in HNSCC; however, the current data are controversial . Whereas some authors have found an increased number of LCs, others have found a reduced number of LCs .…”

“…Infiltration of tumours by DCs reflects the host immune defence mechanism, and has been associated with better prognosis, reduced tumour recurrence rates, and fewer metastases . This has been shown in some malignancies, such as breast, gastric, pancreatic and laryngeal cancers.…”

“…Whereas some authors have found an increased number of LCs, others have found a reduced number of LCs . However, most investigators concluded that there was significant depletion of these cells in tumours as compared with non‐malignant or surrounding tissues …”

“…The function of DCs is to recognise an antigen, process it, and present it to T cells, including recognition of tumour molecules, and capture and cross‐presentation of released tumour‐associated antigens . Moreover, these cells have been reported to be capable of inducing tumour cell death by mechanisms such as Fas‐mediated or nitric oxide‐mediated interactions …”

Tumor infiltrating lymphocytes (TIL) and prognosis in oral cavity squamous carcinoma: A preliminary study

“…Intratumoral macrophages have also been implicated in epithelial-mesenchymal transition in solid malignancies such as non-small cell lung cancer (38) CD68 positive monocytes are primarily activated tissue macrophages that also function in antigen presentation, but there is evidence that some tumor associated fibroblasts (TAF) may also stain with CD68 antibodies (39). Other forms of tumor infiltrating dendritic cells such as Langerhans and CD1a cells have been associated with improved prognosis in head and neck cancers (14,16-18, 40). The potential importance of better understanding of the roles of such antigen presenting cells is reflected in widespread interest in dendritic cell based vaccines which may or may not be of therapeutic benefit in head and neck cancer patients (41).…”