TNF and cystic fibrosis: AZ at concentrations equivalent to peak plasma (0.4 μg·mL−1) and lung peak tissue concentration (10 μg·mL−1) [27], were not able to significantly reduce elevated IL-8 levels observed in TNF-α-stimulated CF HBE (CuFi-1; F508del/F508del) cells (figure 2b).