IL6 and cystic fibrosis: In a study on 35 children with cystic fibrosis, aged 6 to 15 years, the levels of tumor necrosis factor-α, interleukin-1β and IL-6 in the sputum changed over a three-year period and a single determination of these markers had predictive value for a subsequent percentage decline in predicted forced expiratory volume in the first second.28