Langerin+ versus CD1a+ Langerhans cells in human gingival tissue: a comparative and quantitative immunohistochemical study.

Langerhans cells (LC) are dendritic cells of the immune system able to capture intraepithelial pathogens and migrate to regional lymph nodes to present them to naive T cells. Up to now immunohistological studies on human gingival LC have been carried out using antibodies against HLA-DR or CD1a molecules. A new marker of LC called Langerin (CD207) and described, among other subcellular localisations, in the Birbeck granules is now available in immunohistochemistry. The purpose of this in situ study was to quantify and to compare Langerin+ versus CD1a+ LC number in order to show differences in the expression of these molecules, if any, and to determine which marker is the most specific. The present study was conducted using nine frozen healthy gingival samples. Double immunofluorescence procedures were performed with an anti-Langerin antibody revealed by FITC and with an anti-CD1a-PE antibody. Mounted slides were analysed by fluorescence microscopy and quantifications were performed on projected slides associated with a grid of 0.015 mm(2). Our results have shown that 1/ the number of CD1a+ LC was significantly increased (P=0.01) when compared with Langerin+ LC 2/ 92% of Langerin+ LC co-expressed CD1a 3/ only 82% of CD1a+ cells co-expressed Langerin 4/ a positive correlation was noted between CD1a+ and Langerin+ LC numbers. The present study has revealed the heterogeneity in the phenotype of gingival LC population and shown that Langerin seems the most specific marker for the study of LC.