Requirement for sialic acid on neutrophils in a GMP-140 (PADGEM) mediated adhesive interaction with activated platelets

Abstract

Platelet GMP-140, along with ELAM-1 and gp90 MEL, comprise the LEC-CAM family of cell-cell adhesion proteins. The three proteins demonstrate a highly related domain organization, which includes an extracellular calcium-type lectin motif. gp90 MEL, a lymphocyte homing receptor, mediates lymphocyte attachment to high endothelial venules of lymph nodes through recognition of a sialylated ligand on the endothelial cells. The resetting of neutrophils or promyelocytic HL60 cells by activated platelets is mediated by GMP-140 on the platelets. We show here that treatment of neutrophils or HL60 cells with 3 broad spectrum sialidases completely prevents rosetting. However, the Newcastle disease virus sialidase, an enzyme specific for α2,3 and α2,8 linkages of sialic acid does not affect rosetting of HL60 cells. These results indicate that the ligand for GMP-140 requires sialic acid and suggest that an α2,6 linkage may be critical.