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-alpha-activated cremasteric venular endothelium and exhibit marked polarization of surface PSGL-1, but not LFA-1, to the trailing edge.