Bovine gamma/delta T cells bind E-selectin via a novel glycoprotein receptor: first characterization of a lymphocyte/E-selectin interaction in an animal model.

Abstract

SummaryE-Sdectin is an inducible adhesion protein expressed by endothelial ceils and recognized by lenkocytes during their extravasation from the blood into inflamed tissues. Originally, E-sdectin was defined as a mydoid ceil-specific adhesion protein, but recent studies have shown it to be recognized by human lymphocytes as well. These lymphocytes represent a memory T cell subset and have been shown to express the HECA-452 carbohydrate epitope (CLA + lymphocytes). We extend these findings and show that ruminant 3'/8 T cells bind E-sdectin as well; and we provide preliminary evidence that this interaction is mediated by a novel glycoprotein receptor on the lymphocyte. Unlike conventional T ceils (c~/13 T cells), 3'/8 T cells from neonatal and mature animals bind E-sdectin, suggesting that prior antigen stimulation and differentiation to a memory lymphocyte are not required for this interaction. Neuraminidase treatment of the 3'/8 T cells or addition of ethylenediaminetetraacetic acid (EDTA) to the assay abrogates binding, demonstrating the importance of sialic acid and divalent cations, which is consistent with other E-sdectin-mediated adhesion events. However, previously defined E-selectin carbohydrate ligands, such as sialyl Lewis x on nentrophils and the HECA-452 epitope on human memory lymphocytes, are antigenically different than the carbohydrates on ruminant 3'/8 T cells since the mAbs CSLEX and HECA-452 do not recognize these ceils. Protease treatment of 3'/8 T ceils significantly inhibits their binding to E-sdectin; however, previously characterized adhesion glycoproteins, such as L-selectin, CD44, and CD18, are not involved in the adhesive event. An E-sdectin aflinity column purifies a single glycoprotein of 250 kD (280 kD under reducing conditions) from 3'/8 T cell detergent lysates. Nenraminidase digestion of the 250-kD product as well as EDTA abolishes binding to E-sdectin. Finally, E-sdectin expression in vivo appears to mediate 3'/8 T cell accumulation. Stimulation of bovine skin with tumor necrosis factor o~ induced an increase in E-sdectin expression that was associated with an influx of 3'/8 T cells at the same site.

Neutrophils use both shared and distinct mechanisms to adhere to selectins under static and flow conditions.

“…Some of these macromolecules are sialomucins with clustered, sialylated O-linked glycans (11)(12)(13)(14)(15). Other glycoproteins display primarily N-linked oligosaccharides (16,17) or have carbohydrate chains that are less well characterized (18). Neutrophil L-selectin, which displays sLex, has been proposed as a major ligand for E-and P-selectin in part because it is localized on the tips of microvilli (19).…”

Animal Lectins

“…The molecular analysis of natural selectin ligands indicates that not only expression, but also spatial presentation of suitable oligosaccharides will be a key factor for productive in vivo recognition. While the leukocyte lineage-specific L-selectin binds sialylated, fucosylated and sulfated epitopes on diverse much-like glycoproteins including a P-selectin ligand on neutrophils and monocytes which is of importance for enhanced leukocyte recruitment at inflammatory sites (Crottet et al, 1996;Spertini et al, 1996), E-selectin of activated endothelial cells apparently is satisfied with sparsely presented N-linked sugar structures (Levinovitz et al, 1993;Walcheck et al, 1993;Pate1 et al, 1994). Such a glycoprotein scaffold is not sufficient for P-selectin of platelets and endothelial cells.…”

Memory B lymphocytes from secondary lymphoid organs interact with E-selectin through a novel glycoprotein ligand

“…These epitopes were not found to be expressed in resting B lymphocytes ( Figure 6). High-affinity E-selectin ligands, such as PSGL-1, ESL-1, or L-selectin, have been described (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). The expression of PSGL-1 was analyzed using 2 specific mAb's, PSL 275 and KPL-1, the latter specifically recognizing the sulfated NH 2 -terminal domain of this molecule (21).…”

“…Other E-selectinbinding proteins have been identified, including Eselectin ligand-1 (ESL-1), which was described in myeloid cells as a 150-kDa glycoprotein binding via Nlinked oligosaccharides to E-selectin (26,27). A 250-kDa glycoprotein on bovine γ/δ T cells was described as a new E-selectin ligand (24,28).…”