Recirculating lymphocytes initiate extravasation from the blood stream by binding to specialized high endothelial venules (HEV) within peripheral lymph nodes (PN) and other secondary lymphoid organs. We have previously reported that lymphocyte attachment to PN HEV is selectively inhibited by
mannose-6-phosphate (M6P) and related
carbohydrates (Stoolman, L. M., T. S. Tenforde, and S. D. Rosen, 1984, J. Cell Biol., 99:1535-1540). In the present study, we employ a novel cell-surface probe consisting of fluorescent beads derivatized with
PPME, a M6P-rich
polysaccharide.
PPME beads directly identify a
carbohydrate-binding receptor on the surface of mouse lymphocytes. In every way examined, lymphocyte attachment to
PPME beads (measured by flow cytofluorometry) mimics the interaction of lymphocytes with PN HEV (measured in the Stamper-Woodruff in vitro assay): both interactions are selectively inhibited by the same panel of structurally related
carbohydrates, are
calcium-dependent, and are sensitive to mild treatment of the lymphocytes with
trypsin. In addition, thymocytes and a thymic
lymphoma, S49, bind poorly to
PPME beads in correspondence to their weak ability to bind to HEV. When the S49 cell line was subjected to a selection procedure with
PPME beads, the ability of the cells to bind
PPME beads, as well as their ability to bind to PN HEV, increased six- to eightfold. We conclude that a
carbohydrate-binding receptor on mouse lymphocytes, detected by
PPME beads, is involved in lymphocyte attachment to PN HEV.