FAS and cholangiocarcinoma: With this background, the aims of the present study were to investigate: (i) the expression of Fas and FasL in primary cultures isolated from human iCCA; (ii) the in vitro interactions between CCA cells and human PBMCs and the role of Fas/FasL in inducing T-cells and NK cells apoptosis; (iii) in situ the expression of Fas and FasL in human iCCA and their relationship with typical markers of CSC.