Of note, however, LPS challenge led to a significant increase in circulating IL-6 levels (online supplementary figure E6A; p=0.001), and a correlation was seen between 99mTc-neutrophil clearance in the lungs and baseline circulating levels of IL-6 in COPD (p=0.019) and peak IL-6 in the HVs (p<0.001) (figure 3E). The gene discussed is IL6; the disease is chronic obstructive pulmonary disease.