Figure 6.
HL-60 cells and PMNs display upstream migration on HUVEC once Mac-1 is blocked: cell traces of (A) HL-60 cells and (B) neutrophils isolated from whole blood on IL-1β-stimulated HUVECs under isotype (first column), anti-αL-integrin blocking (second column), anti-αM-integrin blocking (third column), anti-α4-integrin blocking (fourth column), or with anti-αM-integrin and anti-α4-integrin blocking (fifth column) at 100 s−1 shear rate. The traces depicted are the cumulative tracks of two independent experiments and have units of microns. Blue traces indicate cells that traveled downstream (with flow), and red traces indicate cells that traveled upstream (against flow). The direction of flow is from left to right, and traces have units of microns. (C) The direction of migration under shear flow as expressed by the MI or (D) percentage of migrating cells traveling upstream under isotype, anti-αL-integrin blocking, anti-αM-integrin blocking, anti-α4-integrin blocking, or anti-αM- and anti-α4-integrin blocking at 100 s−1 shear rate on HUVECs is shown. Both HL-60 cells and PMNs migrate downstream on HUVECs until the αM-integrin is blocked, when they then migrate upstream. Blocking the αL-integrin removes all upstream migration, whereas blocking the α4-integrin with the αM-integrin enhances it. n = 3–4 independent experiments of at least 45 cells analyzed per experiment. ∗p < 0.05 with respect to isotype conditions.