Human renal-cell carcinoma tissue contains dendritic cells

Area of Science:

• Immunology
• Oncology
• Cell Biology

Background:

• Immune surveillance against cancer relies on antigen-presenting cells (APCs) to activate T cells against tumor antigens.
• Dendritic cells (DCs) are the most potent APCs, crucial for initiating adaptive immune responses.

Purpose of the Study:

• To investigate the presence and characteristics of dendritic cells within renal-cell carcinoma (RCC) tissue.
• To assess the functional capacity of tumor-derived DCs in activating T cells.

Main Methods:

• Analysis of leukocytes emigrating from renal-tumor explants using organ culture.
• Characterization of emigrant cells by morphology and expression of cell surface markers (MHC, CD86, CD45RO, CD45RA, CD83).
• Assessment of antigen-capturing ability and allogeneic T cell stimulatory capacity.

Main Results:

• Substantial numbers of mature dendritic cells, identified by cytoplasmic projections and high MHC/CD86 expression, emigrated from RCC explants.
• CD83, a marker for mature DCs, was highly enriched (40-fold) in tumor tissue compared to peripheral blood.
• Tumor-derived DCs showed reduced capacity for soluble antigen uptake but retained the ability to stimulate naive T cells in mixed leukocyte reactions.

Conclusions:

• Genuine, mature dendritic cells infiltrate renal-cell carcinoma tissue.
• The presence of functional APCs in tumors suggests that tumor-associated DCs might be suppressed in situ, contributing to immune evasion in RCC.
• This highlights a potential mechanism for the failure of anti-tumor immune responses in patients with renal cell carcinoma.