A novel glycosylphosphatidyl inositol-anchored protein on human leukocytes: A possible role for regulation of neutrophil adherence and migration

We report here a novel glycosylphosphatidyl-inositol (GPI)-anchored glycopr otein on human leukocytes, Treatment of neutrophils with a mAb (3H9) to thi s molecule sequentially up-regulates and down-regulates beta(2) integrin-de pendent adhesion of these cells as well as their transendothelial migration in vitro. In addition, this mAb simultaneously modulates the avidity of be ta(2) integrin for its ligand, iC3b, with kinetics similar to those observe d in 3H9 modulation of neutrophil adherence, This mAb also induces beta(2) integrin-dependent cytoskeletal remodeling, This novel GPI-anchored protein (GPI-80) is highly homologous with Vanin-1, a recently reported GPI-anchor ed protein that is expressed on perivascular thymic stromal cells and is in volved in thymus homing in mice. The finding that both GPI-80 and Vanin-1 a re 40% homologous with human biotinidase suggests the existence of a biotin idase superfamily of molecules that may be involved in the regulation of le ukocyte trafficking.