Alterations in the frequency of dendritic cell subsets in the peripheral circulation of patients with squamous cell carcinomas of the head and neck.

Patients with advanced squamous cell carcinomas of the head and neck (SCCHN) are frequently immunocompromised. Dendritic cells (DCs) are potent antigen-presenting cells that play a role in antitumor immune responses. Using multicolor flow cytometry, the percentages of lineage-negative (LIN(-)) and DR(+) DC precursors, as well as their LIN(-)DR(+)CD11c(+) (myeloid) and LIN(-)DR(+)CD123(+) (lymphoid) subsets, were determined in the peripheral blood of 36 patients with SCCHN before surgery. Peripheral blood mononuclear cells of 28 age- and sex-matched healthy individuals were used as controls. The proportions of LIN(-)DR(+) cells were found to be comparable in the circulation of patients and controls. However, the relative level of DR expression in LIN(-)DR(+) DC was lower in patients than in controls, suggesting a difference in the maturity of DC. The relative proportion of LIN(-)DR(+)CD123(+) cells in the LIN(-)DR(+) subset of DC did not differ significantly in patients compared with normal individuals. However, the percentage of myeloid-derived LIN(-)DR(+)CD11c(+) DCs was significantly lower (P < 0.002) in SCCHN patients than in controls. Of the 13 patients who were restudied 6 weeks after surgery, 9 showed an increase of the myeloid-derived LIN(-)DR(+)CD11c(+) DC subset postoperatively. This observation suggests that deficiency in the myeloid-derived DC precursors in patients with SCCHN is related to the presence of tumor and is reversible. An overall decrease in the myeloid-derived subset of DC could contribute to the failure of SCCHN patients to develop effective antitumor immune responses.