DDR2 regulates neutrophil directionality in 3D collagen matrices. (A) rDDR treatment does not affect neutrophil chemotaxis in a 3D fibrin gel. Human primary neutrophils were embedded in fibrin (pretreated with or without rDDR). Migration to 50nM IL-8 was recorded (images were taken every 30 seconds with a 5X objective). Migrating cells were tracked for 20 minutes. The percentage, average speed, and CI of migrating neutrophils were determined. Results are representative of 5 independent experiments. (B) rDDR treatment inhibits neutrophil directionality in a 3D collagen matrix. Human primary neutrophils were embedded in collagen I (pretreated with rDDR or not). Migration of neutrophils to 50nM IL-8 was recorded as in panel A. Results are representative of 5 independent experiments. *P = .03, Wilcoxon test. (C) DDR2 inhibition with Ab1 treatment reduces neutrophil directionality in a 3D collagen matrix. Human primary neutrophils were pretreated with blocking DDR2 antibodies or a control IgG for 30 minutes and embedded in collagen I. Migration of neutrophils to 50nM IL-8 was recorded as in panel A. Results are representative of 5 independent experiments. *P = .03, Wilcoxon test.