Analysis of leukocyte recruitment in synovial microcirculation by intravital microscopy.

A complete pattern of adhesion molecules and chemokines involved in leukocyte migration in different tissues and in homeostatic vs inflammatory conditions is still lacking. This chapter describes how to characterize the mechanisms of leukocyte recruitment in synovial vessels in vivo by using epifluorescence videomicroscopy. It has been proposed that inflamed endothelium expresses a combination of adhesion ligands and activating factor(s) for Gi-linked receptors that together orchestrate leukocyte recruitment in vivo. Thus, the combination of molecules involved in the adhesion cascade in synovial vessels may favor the arrest of specific leukocyte subpopulations during different phases of joint inflammation. The approach presented here may provide a useful tool for further investigations of physiologic and pathologic events that occur in normal synovial microcirculation as well as during arthritis.