Immune Suppression in Head and Neck Cancers: A Review

Figure 2

Description of immunosuppressive mechanisms during the head and neck tumor progression: in the normal epithelia of the upper aerodigestive tracts, LCs are present in the suprabasal layers. When mucosae of these areas are exposed to tobacco, the number of LCs increases whereas these cells decrease in invasive carcinomas. The mature DCs are prominent in the peritumoral area and correlated positively with the expression of VEGF. DCs are also more abundant in patients with metastasis. A higher level of TAM is observed in HNSCCs, and these cells constitute a source of VEGF which play a crucial role in angiogenesis. HNSCCs can induce the apoptosis of CD8⁺ T cells using the mitochondrial and/or Fas/FasL pathways. Tregs can induce apoptosis of CD8⁺ T cells and inhibition of the proliferation of CD4⁺ T cells.