A representative flow gating strategy used to assess the percent of S. aureus inside phagosomes of purified, live PMNs (CD66b-positive, zombie-negative cells) is shown in Figure 5C. Similar to attachment, there is enhanced phagocytosis of S. aureus by PMNs incubated with CF sputum compared to those incubated with assay medium alone (Figure 5D). Here, CEACAM8 is linked to cystic fibrosis.