ABSTRACT
Independently of their protective influence, leukocytes can have harmful effects in pathological situations such as diabetes (Benhamou et al., 1990), ischemia-reperfusion injury (Hernandez et al., 1987; Schmid-Schönbein and Engler, 1990; Thornton et al., 1989), inflammatory disorders (Fiebig et al., 1991; Grant, 1973; Jutila, 1992) and vascular permeability disorders (Kubes et al., 1991a; Schoenberg et al., 1991). Their action is mainly due to a rolling phenomenon along venular walls, adhesion to vascular endothelial cells and migration across the endothelium. A number of factors govern the interactions between leukocytes and endothelial cells, including the expression of molecules on the surface of activated leukocytes and/or endothelial cells, certain products of neutrophil activation, and shear forces within blood vessels that tend to sweep leukocytes along the endothelial cell surface (Harlan, 1985; Jutila, 1992; Ley, 1989; Tonnesen, 1989; Zimmerman et al., 1992).
