Imaging receptor microdomains on leukocyte subsets in live mice

We present a simple method to identify the recruitment of leukocyte subsets and determine concurrent surface-receptor clustering in live mice. We show that CD45⁺ F4/80^- Gr-1⁺ neutrophils are robustly recruited in surgery-activated cremasteric venules, whereas adherent CD45⁺ B220⁺ B lymphocytes were dominant in bone marrow venules. Most adherent Gr-1⁺ leukocytes are not firmly stationary but actively migrate on TNF-α-activated cremasteric venular endothelium and exhibit marked polarization of surface PSGL-1, but not LFA-1, to the trailing edge.