The number of regular T cells and immature dendritic cells involved in mycosis fungoides is linked to the tumor stage

BACKGROUND: The balance between immune surveillance and immune escape determines the outcome of patients with primary mycosis fungoides (MF). FOXP3+ regulatory T cells (Tregs) and DC-SIGN+ immature dendritic cells (imDCs) play a central role in regulating the immune state in the progression of MF. However, whether the mechanisms used by these factors depend on MF stage is still underdetermined and even controversial. PATIENTS AND METHODS: FOXP3+ Tregs and DC-SIGN+ imDCs were detected by immunohistochemical staining of formalin-fixed, paraffin-embedded specimens obtained from the lesion biopsies of 89 patients with MF, comprising 69 patients at the patch stage, 12 at the plaque stage, and 8 at the tumor stage. The number of FOXP3+ Tregs and DC-SIGN+ imDCs in each stage was counted and compared. RESULTS: The expression of FOXP3 and DC-SIGN varied with the MF stage. The number of cells expressing FOXP3 was higher at the patch and plaque stages than at the tumor stage (p < 0.05), but no significant difference was noted between the patch and plaque stages (p = 0.715). DC-SIGN expression increased continuously, concomitant with tumor progression, through the three stages (p < 0.05). CONCLUSIONS: The predominant factor influencing the immune state is different for each MF stage. Therefore, therapeutic strategies that modulate the antitumor immune responses should be developed depending on MF progression.