Immune Check Point CD40–CD40L Activates Dendritic and Effector Cells Against Human Renal Carcinoma Cells

BACKGROUND/AIM: Adenoviral-mediated expression of CD40 ligand (CD40L) on dendritic cells (DCs) activates immune check point CD40/CD40L, enhancing the immunostimulation of DCs and effector cells against human renal carcinoma cells (RCC) and inducing tumor cell apoptosis in vitro. MATERIALS AND METHODS: DCs, isolated from buffy coats from healthy donors, were transduced with adenoviruses carrying human CD40L (Ad-hCD40L). Subsequently maturation marker and cytokine expression were analyzed by fluorescence-activated cell sorting and enzyme-linked immunosorbent assay. RESULTS: Adenoviral transduction induced high expression of soluble CD40L and membrane-bound CD40L, leading to a strong CD40-CD40L interaction in DCs. Interestingly, a T-helper cell type 1 shift of expressed cytokines/chemokines was observed due to the expression of membrane-bound CD40L rather than due to soIuble CD40L alone, which significantly reduced immunoactivation of DCs. However, supernatants of Ad-hCD40L-transduced DCs induced apoptosis of RCC cells. Co-culture of Ad-hCD40L DCs with cytokine-induced killer cells led to a significant stimulation of tumor-specific cytokine-induced killer cells, with increased proliferation and cytotoxicity. CONCLUSION: Use of Ad-hCD40L-transduced DCs is a promising approach to treating RCC.