Significant association of high-grade inflammation and thick lining epithelium with the increased number of Langerhans cells in dentigerous cysts

Background/purpose Langerhans cells (LCs) are antigen-presenting cells. This study assessed the LC counts in 80 dentigerous cysts (DCs). Methods The CD1a-positive LC numbers in the lining epithelia and subepithelial connective tissues were counted at 80 DC sites without inflammation, 33 DC sites with mild/moderate inflammation, and 9 DC sites with severe inflammation from 80 DC specimens. Results The mean LC counts in the lining epithelia and subepithelial connective tissues increased significantly from no inflammation (0.5 ± 0.5 and 0.2 ± 0.3 cell/high-power field or HPF, respectively) through mild/moderate inflammation (6.8 ± 1.8 and 2.4 ± 2.0 cells/HPF, respectively) to severe inflammation DC sites (18.9 ± 7.0 and 6.7 ± 5.8 cells/HPF, respectively; all P-values < 0.001). DC sites with inflammation had thicker lining epithelia than those without inflammation. Moreover, the mean LC counts in the lining epithelia and subepithelial connective tissues of DCs were significantly higher in the thicker lining epithelium (>50 μm) group (7.4 ± 6.5 and 2.6 ± 3.4 cells/HPF, respectively) than in the thinner lining epithelium (≦ 50 μm) group (0.5 ± 0.5 and 0.2 ± 0.3 cells/HPF, respectively; both P-values < 0.001). Conclusion A significant association of high-grade inflammation and thick lining epithelium with the increased LC number in DCs is found. The finding of few LCs in the lining epithelia of DCs without inflammation indicates the reduced immunosurveillance ability against DC lining epithelial cells in DC patients. It needs further studies to confirm the role of reduced immunosurveillance in the enlargement of the DC.