Soluble uric acid affects β₂ integrin activation and prevents human neutrophil migration and phagocytosis in vitro. (A) Human neutrophils were isolated from healthy individuals and preincubated with or without 10 mg/dL sUA for 30 minutes prior to stimulation with human CXCL8 or SARS-CoV2–derived DAMP/PAMP supernatant. (B) Schematic of the 3 β₂ integrin conformations that reflect the different affinity stages: (1) the bent form, inactive, (2) the extended form with a closed ligand-binding head of intermediate affinity, and (3) the extended form enabling the ligand-binding for mAB24 with high affinity (adopted from Evans et al).⁸² (C-D) mAB24 binding illustrated as a histogram (C) and the expression levels of mAB24 (D) determined by flow cytometry (n = 6-7 per group). (E-F) The expression levels of LFA-1 (E) and MAC-1 (F) shown as mean fluorescence intensity (MFI) relative to isotype control (n = 6-7 per group) were quantified by flow cytometry. (G-H) Transwell migration assays were carried out, and the total number of neutrophils that migrated toward the chemoattractants human CXCL8 and IL-1β (G) and fMLP (H) was determined after 3 hours by flow cytometry (n = 6-12 per group). (I-J) The expression levels of LFA-1 (I) and MAC-1 (J) shown as MFI relative to isotype control (n = 4 per group) were quantified by flow cytometry. (K) Transwell migration assays were carried out, and the total number of neutrophils that migrated toward the SARS-CoV2 supernatant (20%) was determined after 3 hours by flow cytometry (n = 4 per group). (L) Percentage (%) of phagocytosed IgG FITC-latex beads in untreated or CXCL8-stimulated neutrophils with or without sUA preincubation was determined by flow cytometry (n = 4 per group). Data are mean plus or minus SD. *P < .05, **P < .01, ***P < .001. ns, not significant by 2-way ANOVA; Ctrl, control; IgG, immunoglobulin G.