Since atypical activation of the UPR has been reported in CF (15), characterized by high levels of XBP1s and IL-6, we aimed to investigate firstly, whether these UPR abnormalities were present in individual subsets of immune cells, then secondly, the nature of the metabolic conditions of immune cells affected by ER stress and finally, the implications of the IRE1α-XBP1 pathway in the metabolic profile of CF immune cells. The gene discussed is XBP1; the disease is cystic fibrosis.