Expression of Langerhans cells, dermal dendritic cells, and plasmacytoid dendritic cells in early stage mycosis fungoides: a case–control study

Background One possible mechanism explaining the prolonged disease development in early stage mycosis fungoides (MF) could be that the patient’s immune system controls tumor progression by an antitumor immune response in which dendritic cells (DCs) are thought to actively participate. Objective The aim of the study was to focus on evaluating the three lineages of DCs, Langerhans cells (LCs), dermal dendritic cells (DDCs), and plasmacytoid dendritic cells (pDCs), through determining the expression of their markers CD1a, factor XIIIa, and CD123, respectively, in the early stage MF. Patients and methods A total of 16 patients with early stage MF and six controls were included. Skin biopsies underwent immunohistochemical staining for CD1a, factor XIIIa, and CD123. Results The mean number of positive cells of both CD1a-positive LCs and factor XIIIa DDcs was significantly higher in the MF patients in comparison with the controls (P= 0.001 and 0.013, respectively). However, no significant difference was documented regarding the mean number of CD123-positive pDCs between MF patients (0.77 ±0.95) and controls (0.22± 0.47) (P= 0.13). Receiver operator characteristic analysis revealed that the area under the curve of CD1a-positive LCs and factor XIIIa DDcs was 0.948 and 0.844, with the best cutoff values of 3.167 and 5.83, which achieved sensitivity of 100%, specificity of 67% and sensitivity 100%, specificity 67%, respectively. Conclusion A possible role is played by LCs, DDCs, and pDCs in the pathogenesis of MF. However, whether the DCs appeared in reaction to tumor cells to antagonize their progression or to be a source for chronic antigenic stimulation resulting in the immune escape of tumor cells and perpetuation of the disease needs more clarification.