Increase of DC-LAMP+ mature dendritic cell subsets in dermatopathic lymphadenitis of mycosis fungoides.

Abstract

Little is known about the immunological milieu of the skin-draining lymph nodes (LNs) in mycosis fungoides (MF). We studied dendritic cell (DC) subsets in the dermatopathic lymphadenitis of MF patients. We immunohistochemically examined DC subsets and their distribution in 16 LN samples from 14 patients with MF (N1 LN, eight patients; N2, four; and N3, four), and we compared them with non-metastatic sentinel LNs from eight patients with melanoma. The number of S-100 protein+ DCs was markedly increased in the LNs from the MF patients and the major component was DC-LAMP+ mature DCs in the outer and paracortex areas, where DC-SIGN+ immature DCs were relatively decreased in proportion. In contrast, DC-SIGN+ cells were relatively increased in proportion compared to DC-LAMP+ cells in the medulla. Although no significant difference was observed in the proportions of CD1a+ or Langerin+ DCs among the N1, N2, and N3 nodes, CD163+ M2-type macrophages were increased in number in the N2 and N3 nodes. Our observations indicate that mature DCs accumulate in the outer and paracortex areas in dermatopathic lymphadenitis and M2-type macrophages might increase in number during disease progression.