Association between langerhans cells population and histological grade of oral squamous cell carcinoma

Langerhans cells (LCs) are a unique population of antigen processing cells in the epidermis and mucous membrane, which may play a role in the defence mechanism against epithelial tumors. To compare the distribution of LCs in oral squamous cell carcinomas (OSCC) and normal oral epithelium; and to determine whether the population of LCs in OSCC has any correlation with histological grading of these malignancies. A cross-sectional immunohistochemical analysis of OSCC cases. Forty-eight randomly selected paraffin tissue blocks of OSCC cases and 30 cases of normal oral epithelium were included. Hematoxylin and eosin-stained sections of the OSCC cases were reviewed and categorized as high-grade malignant tumors or low-grade malignant tumors. Tissue sections were analyzed for density of LCs using CD1a antibody expression. Data are expressed as percentages compared by Chi-square statistics; mean ± standard deviation, compared by Mann-Whitney-U test and Spearman's correlation tests. LCs population was significantly higher in normal oral epithelium when compared with OSCC cases (P = 0.001). There was also a significant difference in the number of LCs per millimetre square area of tissue section between well-differentiated tumors and poorly-differentiated tumours (P = 0.03). There was a negative correlation between the population density of LCs and the grade of OSCC. These findings suggest that oral mucosal LCs are involved in immune-surveillance and immunologic impairment may characterize invasive OSCC. In addition, LCs density characterizes histological grades of OSCC, which may be of a prognostic value.