Figure 2. Phenotypic characteristics of neutrophil populations.

(A) Wright-Giemsa staining of sorted CD66b⁺ CD16^Neg (left), CD16^Int (middle), and CD16^hi (right) populations show different stages of neutrophil maturation. (B) Representative cluster maps of CD66b⁺ neutrophil subsets in moderate and severe COVID-19 patients compared with Cm Ctrl and HD groups. (C) Representative histograms showing indicated surface molecule expression levels on CD16^hi (blue) and CD16^Int (red) LDNs. Cells were gated on the viable CD66b⁺ population. (D) viSNE cluster plots highlight the expression of CD11b and CD44 in the CD16^Int (blue circle) and CD16^hi (red circle) neutrophil populations. (E) Using mass cytometry, CD44 expression on CD66b⁺ neutrophils from HD (n = 6), Cm Ctrl (n = 9), and moderate (n = 24) and severe (n = 12) COVID-19 patients is shown. Representative dot plots and summarized data are shown. Data are presented as mean ± SD. P values were determined using 1-way ANOVA with multiple comparisons. **P < 0.01, ***P < 0.001.