(A) Mean fluorescent intensity of neutrophils pretreated with THP (50 μg/mL) or not (control), stained with FITC mouse anti-human THP antibody. (B) ROS production of neutrophils pretreated with THP or not (control), with or without PMA stimulation. (C) Transwell migration of neutrophils, pretreated with THP or not (+ control), in response to chemoattractant fMLP. Background neutrophil migration was recorded in the absence of fMLP (- control). (D) Percent survival (left) and recovered CFU (right) of UPEC UTI89 after 30 min of exposure to neutrophils pretreated with THP or not (control). (E)Plate-based binding assays of immobilized THP with human Siglec-Fcs and visualized with PE anti-human IgG Fc antibody. (F) Mean fluorescent intensity (F) or ROS production (G) of neutrophils pretreated with mouse anti-human Siglec-9 (sialic acid blocking, Sia) or anti-human Siglec-9 (Hyaluronic acid blocking, HA) antibodies, and treated with THP or not (control). Data represent the mean of two independent experiments performed in technical triplicate with combined results, n = 2/group (E), or three independent experiments performed in technical triplicate with the mean and SEM of combined results, n = 3/group (all other panels). Data was analyzed using Student's unpaired two-tailed t-test (A,D), two-way ANOVA with Bonferroni's multiple comparisons post-test (B, E), or one-way ANOVA with Bonferroni's multiple comparisons post-test (C, F-G). *P < 0.05, **P < 0.01, and ****P < 0.0001 represent statistical significance, or n.s. represents non-significant (P > 0.05).