DC maturation and function are not altered by melanoma-derived immunosuppressive soluble factors

Immunosuppressive effect of renal cell carcinoma on phenotype and function of dendritic cells

Dendritic cells (DCs) play an important role in anti-renal cell carcinoma (RCC) immunity. The aim of the study was to investigate effect of mimic RCC microenvironment on phenotype and function of DCs. We isolated conditioned media (CM) from supernatants of culturing RCC cells and adjacent non-RCC cells in patients. CD14+ monocytes were obtained from healthy donors. The monocytes derived DCs were treated by RCC CM and non-RCC CM. Maturation markers CD80, CD83, CD86, and HLA-DR on DCs were analyzed using flow cytometry, while the levels of IL-10, TGF-β, and IL12p70 in supernatants were examined by ELISA. The DCs migration treated with RCC CM and non-RCC CM was investigated using transwell assay. The DCs treated and allogenic T cells were co-cultured for detecting T-cell proliferation and change of phenotype on the T cells. Our results indicated that RCC CM inhibited the up-regulation of CD80,CD83, CD86, and HLA-DR in response to LPS in treated DCs and increased IL-10 and TGF-β secretion but reduced IL12p70 production. Moreover, the migration ability of DCs treated with RCC CM was also inhibited, compared to DCs treated with adjacent non-RCC CM. In addition, T-cell proliferation was suppressed in co-culture assay with DCs treated with RCC CM; proportion CD25+Foxp3+ regulatory T cells were induced to increase. This study suggests that RCC CM can inhibit maturation of DCs and impair its function; moreover, DCs treated with RCC CM induce regulatory T cells increase, thus could contribute RCC escape from antitumor immunity.

Role of tumor-infiltrating CD11b+ antigen-presenting cells in the progression of gastric cancer

BACKGROUND

Tumor-infiltrating antigen-presenting cells (APCs), involving tumor-associated macrophages and tumor-infiltrating dendritic cells, play an important role in tumor immunity and immune escape. The aim of this study was to determine whether tumor infiltrating CD11b(+) APCs may affect tumor progression and clinical outcome.

METHODS

The immunohistochemical analysis was used to evaluate the expression of CD11b, FOXP3, and CD8 in 214 gastric cancer tissues. Concentrations of immunosuppressive cytokines in medium conditioned by gastric cancer cells were measured by enzyme-linked immunosorbent assay. Effects of addition of tumor-conditioned media on CD11c(+) cells were examined by flow cytometry.

RESULTS

Almost all tumor-infiltrating CD11b(+) cell expressed CD11c and was considered to be APCs. High CD11b(+) cell infiltration was significantly correlated with huge tumor, positive venous invasion, lymph node metastasis, and tumor, node, metastasis stage. Patients with high CD11b(+) cell infiltration had a poorer surgical outcome than those with low CD11b infiltration. Multivariate analysis revealed that CD11b(+) cell infiltration was one of the independent prognostic factors. Tumor-conditioned medium obtained from several gastric cancer cell lines contained immunosuppressive cytokines, transforming growth factor-beta, interleukin-10, and vascular endothelial growth factor. The addition of tumor-conditioned medium decreased the expression of major histocompatibility complex-II and increased the expression of CD11b and programmed death ligand 2 on CD11c(+) APCs. Infiltration of CD11b(+) cells significantly correlate with the degree of FOXP3(+) cell infiltration but not with CD8(+) cell infiltration.

CONCLUSIONS

Tumor-infiltrating CD11b(+) APCs affected local tumor cell-immune cell interactions and correlated to the poor prognosis of the patients with gastric cancer.

Numerical defect of circulating dendritic cell subsets and defective dendritic cell generation from monocytes of patients with advanced melanoma

The behaviour of circulating dendritic cells (DCs) and DC generation from monocytes in melanoma patients during the progression of disease have not been described. We report a significant decrease in the absolute number of total DCs, which mainly affects plasmacytoid DCs in stage IV. Additionally, monocyte-DC generation is less efficient in advanced stages, resulting in DCs that exhibit increased phagocytic capacity, potentially indicating a less mature state. These findings elucidate aspects of basic tumour-mediated immunosuppression, which may have implications for immunotherapeutic approaches, suggesting that the selection of patients for immunotherapy should also be made on the basis of their immune status.