Fig. 1.

Activated neutrophils display increased surface binding of sRAGE. A The number of neutrophils was measured in blood of 77 intermittent smokers without airway obstruction. Blood was collected after at least two days without smoking (before smoking) and two hours after smoking three cigarettes within one hour (after smoking). The percentage of neutrophils was determined by flow cytometry. The granulocyte population was 7 isolated using forward and sideward scatter characteristics and the neutrophil population was characterized as CD62Lhigh expressing granulocytes. B CD11b expression was assessed on blood leucocytes before and after smoking using flow cytometry. C The association between the percentage decrease in serum sRAGE levels before and after smoking with the expression of CD11b on neutrophils after smoking. D–E Neutrophils were isolated from healthy controls (n = 5) and incubated for one hour in RPMI with 10% fetal calf serum and 50 ng/mL recombinant sRAGE. The effect of activation by 100 nM N-Formylmethionyl-leucyl-phenylalanine (fMLP) for hour on the surface expression of CD11b and RAGE was assessed by flow cytometry. F The residual levels of sRAGE after activation with 100 nM fMLP for one hour were assessed in cell-free supernatant using ELISA. Data are shown as individual data points or mean ± SEM. Statistical significance was assessed using a Mann–Whitney U test to compare conditions or with a linear regression analysis to assess associations, * p < 0.05, *** P < 0.001