Figure 1.

Leukocyte counts, their vascular partition, and neutrophil margination in the lung vasculature are not affected by loss of ICAM-1 and ICAM-2. The relative numbers of neutrophils (CD45⁺CD11b⁺Ly6G⁺) (A), classical (Ly6C^hi) monocytes (CD45⁺CD11b⁺Ly6G^-Ly6C^hi) (B), NK cells (CD45⁺CD11b⁺NKp46⁺) (C), patrolling (Ly6C^lo) monocytes (CD45⁺CD11b⁺Ly6G^-Ly6C^low) (D) and Tregs (CD45⁺CD4⁺CD25⁺Foxp3⁺) (E) in the indicated organs. The partition of each leukocyte type in intravascular (red) and extravascular (white) organ compartments is shown in the insets next to each graph. n= 5 for all bone marrow determinations; n= 5-12 for spleen; n= 5-13 for lung determinations of either WT or ICAM-1/2^-/- mice and n=12-14 for blood samples analyzed for each leukocyte type. Data were combined from at least 2 independent experiments. (F) Pulmonary intravital microscopy of neutrophils marginating in either WT or ICAM-1/2^-/- lungs. The experimental design is shown in the left panel. Neutrophils and blood vessels were stained by I.V. injection with the indicated fluorescently labeled mAbs. The middle panel depicts representative still images from two-photon video microscopy movies (scale bars represent 128 μm), and the bar graph shows the total neutrophils per field of view (FOV) as assessed by imaging. The total numbers of circulating and adherent neutrophils and their dynamic phenotypes grouped in three categories (tethering, crawling and arrested (stationary)) are depicted in the right panels. n= 8 for each group. Statistical significance was determined by two-tailed, unpaired Student’s t tests. *P < 0.05, ****P < 0.0001, ns, not significant. The error bars indicate the SEM of each measurement.