Localized extravascular chemokine release induces directional intraluminal crawling of neutrophils toward infection site. (A) Number of adherent neutrophils per 100-μm venule and (B) number of emigrated neutrophils per field of view, in untreated (n = 3) WT cremaster muscle or activated by MIP-2 superfusion (n = 7) or an MIP-2-containing gel (n = 5). (C) Percentage of all adherent neutrophils that crawled within the observed vessel section before transmigration (MIP-2 SF, n = 67, 4 mice; MIP-2 gel, n = 100, 5 mice). (D-E) Displacement of crawling neutrophils (with crawling start and endpoints within the field of view) from the adhesion point (the center of the circle) to transmigration site (marked dots) during activation by (D) MIP-2 superfusion (n = 32, 4 mice) or by (E) an MIP-2-containing gel (n = 57, 5 mice) placed at 90 degrees at a distance of 400 μm from the venule. The vertical axis in the plot corresponds to the direction of blood flow (toward 0 degrees). *P < .05 compared with time 0 before addition of chemokine. †P < .05 vs WT untreated.