Identification of an inducible endothelial-leukocyte adhesion molecule.

TLDR

Leukocyte accumulation at inflamed sites requires adhesion to the vascular lining. The study tests whether inducible endothelial surface structures mediate leukocyte adhesion. Cytokines and endotoxin stimulate endothelial cells to express an inducible adhesion molecule (ELAM‑1) that binds leukocytes; monoclonal antibodies H18/7 and H4/18 recognize this protein, immunoprecipitate 115‑kDa and 97‑kDa polypeptides, and inhibit leukocyte adhesion by more than 50 %.

Abstract

The accumulation of blood leukocytes at sites of inflammation depends upon their localized adhesion to the vascular lining. We have investigated the hypothesis that this adhesive interaction involves inducible endothelial cell-surface structures that can bind leukocytes. Certain inflammatory/immune cytokines, namely interleukin 1, tumor necrosis factor, and lymphotoxin, as well as bacterial endotoxin, act on cultured human endothelial cells (HEC) in a time- and protein-synthesis-dependent fashion to increase leukocyte adhesion. We have developed two monoclonal antibodies (mAbs), H18/7 and H4/18, that identify a cell-surface antigen expressed on cytokine- and endotoxin-stimulated HEC but not on unstimulated HEC. Both mAbs immunoprecipitate the same polypeptides (major species, Mr 115,000; minor species, Mr 97,000, reduced) from biosynthetically labeled cytokine-stimulated HEC. The mediator specificity and kinetics of HEC expression of this protein(s) correlate with increased adhesiveness for leukocytes. In standardized endothelial-leukocyte adhesion assays, mAb H18/7 inhibits the adhesion of polymorphonuclear leukocytes (greater than 50%) and HL-60 cells (greater than 60%) to stimulated HEC by comparison to isotype-matched control mAb; mAb H4/18 also inhibits HL-60 adhesion but to a lesser extent. We have designated the inducible endothelial cell-surface protein recognized by mAb H18/7 and H4/18 "endothelial-leukocyte adhesion molecule-1 (ELAM-1)."