COMPARISON OF E-SELECTIN-BINDING GLYCOPROTEIN LIGANDS ON HUMAN-LYMPHOCYTES, NEUTROPHILS, AND BOVINE GAMMA-DELTA T-CELLS

We compared E-selectin-binding cell surface ligands on bovine gamma de lta T cells and human leukocytes using an E-selectin/Ig chimera. The c himera worked well in flow cytometric studies and showed that bovine g amma delta T cells were the only lymphocyte population in newborn anim als that bound E-selectin chimera, Furthermore, the chimera blocked ga mma delta T cell rolling on E-selectin, Chimera reacted with four pote ntial glycoprotein ligands of 180, 200, 250, and 300 kDa in Western bl ot analysis of gamma delta T cell detergent lysates, and it specifical ly precipitated at least two of these E-selectin ligands (200 and 250 kDa) from lysates of cell surface biotinylated gamma delta T cells, Pr eclearing bovine gamma delta lysates of GD3.5 Ag and workshop cluster 1 did not abrogate E-selectin ligand precipitation, suggesting that th ese surface markers do not represent E-selectin ligands, Human neutrop hils possessed three E-selectin-binding ligands of approximately 80 to 90, 130, and 230 kDa, while human lymphocytes variably possessed thre e ligands of 120, similar to 220 to 240, and 260 kDa, Cross-precipitat ion experiments confirmed the results of others that neutrophil L-sele ctin serves as the 80 to 90-kDa E-selectin ligand, The human lymphocyt e similar to 220 to 240-kDa and 260-kDa ligands may be analogous to th e bovine gamma delta T cell molecules, whereas the 120-kDa is unique t o human cells, The identities of the human and bovine lymphocyte E-sel ectin ligands are unknown, Finally, E-selectin ligand-1 apparently may have a minimal role, if any, in lymphocyte/E-selectin interactions, s ince a polyclonal anti-E-selectin ligand-1 serum stained a minimal num ber of cutaneous lymphocyte-associated Ag-positive human lymphocytes a nd bovine gamma delta T cells.