Neutrophils from Hbb^th3/+ mice have reduced phagocytic activity. Whole cell populations from (A) BM, (B) blood, and (C) spleen were incubated with opsonized AF488-labeled S aureus. At indicated time points, the percentage of neutrophils (CD49b^negCD11b⁺Ly6G^high) that phagocytosed bacteria was determined by flow cytometry. Statistical significance between WT and Hbb^th3/+ mice (A-C) was evaluated using 2-way analysis of variance (ANOVA). Representative expression of CD11b on Ly6G^high cells in (D) BM, (E) blood, and (F) spleen in naive animals. Dark shading corresponds to WT; red shading for Hbb^th3/+, and yellow shading for isotype control staining. (G) Relative CD11b expression levels as determined by measuring MFI in Ly6G^high cells obtained from naive cells. (H) Alterations in surface expression of CD11b on CD11b⁺Ly6G^high splenic neutrophils derived at 0, 10, 20, and 30 minutes after S aureus stimulation. Neutrophils (CD11b+Ly6G^hi) were classified into 2 groups, based on CD11b expression (CD11b^low and CD11b^high). (I) Percentage of CD11b^high neutrophils following S aureus stimulation. Statistical significance between WT and Hbb^th3/+ mice was evaluated using 2-way ANOVA. (J) Comparison of S aureus phagocytosis between CD11b^low and CD11b^high neutrophils (Ly6G^high) following 30 minutes exposure to opsonized heat-killed S aureus. Values are presented as average means of 3 mice per group ± SEM. Results representative of 3 independent experiments are shown. The statistical significance between the groups was evaluated with Student t test.