VCAM-1 and its functions in development and inflammatory diseases.

VCAM-1 was identified in endothelium by monoclonal antibody and expression cloning approaches [1-3] . These approaches, as well as the discovery of other endothelial cell adhesion molecules, were dependent on the development of efficient and reproducible techniques for culturing human umbilical vein endothelial cells, and on observations that treatment with inflammatory cytokines, such as interleukin-1 (IL-1) and tumor necrosis factor-α (TNF), or with bacterial endotoxin resulted in endothelial activation [4]. Cytokine activation alters the phenotype of quiescent endothelial cells, resulting in a protein synthesis-dependent hyperadhesive state for leukocytes. The monoclonal antibody studies involved immunizing mice with activated endothelium and screening for monoclonal antibodies that recognized cytokine-inducible epitopes. The antibodies were then used to identify unique proteins by immunoprecipitation and leukocyte adhesion function was ascertained by antibody adhesion-blocking assays. Expression cloning used a subtracted cytokine-activated human umbilical vein endothelial cell library packaged in a eukaryotic expression vector that was transiently expressed in transfected COS cells, and cDNA from cells exhibiting increased leukocyte adhesion was extracted amplified, retransfected and rescreened [3]. [ABSTRACT FROM AUTHOR]