Current Biology
Volume 5, Issue 6, June 1995, Pages 670-678
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Research Paper
Selective modulation of the expression of L-selectin ligands by an immune response

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Abstract

Background: The adhesion molecule L-selectin is expressed on the cell surface of lymphocytes and mediates their migration from the bloodstream into lymph nodes. L-selectin is able to recognize four glycoprotein ligands, three of which — Sgp50, Sgp90 and Sgp200 — are sulphated, bind specifically to L-selectin and are synthesized by the high endothelial venules of the peripheral and mesenteric lymph nodes. One of these three sulphated L-selectin ligands, Sgp90, has been shown to be identical to the known surface marker CD34 and is expressed on the cell surface of endothelial cells. The cDNA encoding Sgp50 has been cloned, and its product, which has been designated GlyCAM-1, is secreted. The third ligand, Sgp200, is both secreted and cell-associated. We have investigated how the expression of these sulphated glycoproteins is regulated during an immune response.

Results Here we demonstrate that, during a primary immune response, the expression and secretion of both GlyCAM-1 and Sgp200 are reduced, recovering to normal levels 7–10 days after antigen stimulation. In contrast, the expression of cell-associated CD34 and Sgp200 is relatively unaffected. These results may account for the modest decreases in the binding of an L-selectin–IgG fusion protein to high endothelial venules of inflamed peripheral lymph nodes that have been observed after antigen exposure. In vivo experiments show that, following the decrease in the levels of secreted GlyCAM-1 and Sgp200, migration of lymphocytes from the blood stream into lymph nodes remains L-selectin-dependent, but more lymphocytes home to antigen-primed than unprimed peripheral lymph nodes.

Conclusion We suggest that the secreted forms of the L-selectin ligands GlyCAM-1 and Sgp200 act as modulators of cell adhesion, and that cell-associated CD34 and Sgp200 are the ligands that mediate the initial loose binding of lymphocytes to high endothelial venules.

Cited by (0)

David Hoke, Donald Dowbenko, Peter Gribling, Susanne Baumhueter and Susan R. Watson (corresponding author), Department of Immunology, Genentech, 460 Point San Bruno Boulevard, South San Francisco, California 94080, USA.

Reina E. Mebius, Department of Pathology and Developmental Biology, Stanford University, Palo Alto, California 94530, USA.

Noel Dybdal and Carrie Kyle, Department of Toxicology and Pathology, Genentech, 460 Point San Bruno Boulevard, South San Francisco , California 94080, USA.

E-mail address for Susan R. Watson: [email protected]