Beschreibung:
AbstractLeukocyte adhesion to endothelial cells and migration into the subendothelial matrix was studied with a three‐dimensional model system, consisting of human endothelial cells cultured on a loose collagen matrix. We developed a new method to separate the endothelial cell monolayer and adhering leukocytes from the subendothelial matrix, allowing simultaneous analysis of leukocyte adhesion and transendothelial migration. Monocytes adhered more avidly to untreated endothelial cells than did neutrophils (2.5 ± 0.3 vs. 1.0 ± 0.2 leukocytes per endothelial cell). Only a small fraction (10%–20%) of these leukocytes migrated into the subendothelium. Pretreatment of endothelial cells with interleukin 1 (IL1) enhanced adhesion (20%), but not migration of monocytes. In contrast, neutrophil adhesion was markedly and in a time‐dependent manner increased by IL1 treatment (i.e. 200% after 6h and 110% after 24 h of IL1 treatment). Moreover, IL1 pretreatment enhanced neutrophil migration twofold. Activation of leukocytes with formyl‐methionyl‐leucyl‐phenylalanine (fMLP) enhanced both monocyte and neutrophil adhesion, but did not affect leukocyte migration. Under all conditions, monocyte adhesion was only partly (30%–40%) inhibited by monoclonal antibodies (mAb) against the common β subunit of the leukocyte‐cell adhesion molecules (LeuCAM; CD 18) and 25%–30% by mAb against the α subunit of LFA‐1 (CD11a). In contrast, mAb against the α subunits of Mac‐1 (CD11b) and p150, 95 (CD11c) were hardly effective. fMLP‐mediated neutrophil adhesion was reduced to below baseline levels by anti‐LeuCAM (CD18) mAb, whereas the LeuCAM contribution in IL 1‐mediated neutrophil adhesion was less pronounced and varied in time. IL 1‐mediated neutrophil migration, however, was completely blocked by anti‐LeuCAM mAb. fMLP‐mediated neutrophil adhesion was inhibited by mAb against the α subunits of Mac, while mAb against the α subunits of LFA‐1 and Mac‐1 both reduced IL 1‐mediated adherence. In summary, we describe a novel leukocyte adhesion/migration method and demonstrate that the contribution of the LeuCAM complex in leukocyte‐endothelium interaction varies depending on cell type and stimulus used.