[Immune microenvironment of Langerhans cell histiocytosis: from immune suppression to targeted therapy]

Langerhans cell histiocytosis (LCH) is a rare hematologic disorder characterized by the clonal proliferation of neoplastic dendritic cells (DCs), exhibiting both immature and senescent immune phenotypes. The immunosuppressive microenvironment in LCH includes an increased proportion of regulatory T (Treg) cells with inhibitory functions, as well as exhausted CD8(+) T cells and myeloid-derived suppressor cells, which collectively exacerbate immunosuppression and facilitate the immune evasion of tumor DCs. Current therapeutic approaches for LCH are limited by the challenges of relapse and drug resistance. However, emerging strategies that target the senescent phenotype of neoplastic DCs, inhibit Treg cell activity, and reverse T cell exhaustion through immune checkpoint blockade offer promising avenues for the treatment of LCH.