Langerhans Cells Correlate With Macrophages for Defense Mechanisms in the Atrophic Epithelium of Radicular Cysts.

Langerhans cells (LCs) play important roles in cell-mediated immune reactions, as well as in the pathogenesis of periapical lesions. The aim of this study is to evaluate the role of LCs in the proliferative epithelium of radicular cysts (RCs) and the release of the proinflammatory cytokine tumor necrosis factor α (TNF-α) associated with epithelial thickness. Thirty cases of RCs and 30 cases of residual RCs were randomly selected. Morphologic analysis was performed to evaluate the association between the inflammatory infiltrate, cystic epithelial thickness and lesion size, in addition to immunohistochemical assessment of CD1a, CD68, and TNF-α. The highest macrophage percentages and TNF-α scores were found in RCs (P=0.038 and 0.017, respectively). The largest number of LCs was observed in RCs (P=0.021), especially those exhibiting atrophic epithelium (P=0.05). In addition, LCs were positively correlated with the number of macrophages in both RCs and residual RCs (P=0.033 and 0.002, respectively). In contrast to LCs, the largest number of macrophages was detected in cases with an intense inflammatory infiltrate (P=0.022). In addition, the highest TNF-α scores were associated with an intense inflammatory infiltrate (P=0.024) when analyzed in the capsule of RCs (P=0.017). In conclusion, LCs participate in defense mechanisms and were present in all cases evaluated. Along with macrophages, these cells release proinflammatory cytokines such as TNF-α, which is responsible for inducing the continued proliferation of cystic epithelium.