Cutting Edge: CD43 Functions as a T Cell Counterreceptor for the Macrophage Adhesion Receptor Sialoadhesin (Siglec-1)

Abstract

Sialoadhesin (Siglec-1) is a macrophage-restricted sialic acid-binding receptor that mediates interactions with hemopoietic cells, including lymphocytes. In this study, we identify sialoadhesin counterreceptors on T lymphocytes. Several major glycoproteins (85, 130, 240 kDa) were precipitated by sialoadhesin-Fc fusion proteins from a murine T cell line (TK-1). Binding of sialoadhesin to these glycoproteins was sialic acid dependent and was abolished by mutation of a critical residue (R97A) of the sialic acid binding site in the membrane distal Ig-like domain of sialoadhesin. The 130- and 240-kDa sialoadhesin-binding glycoproteins were identified as the sialomucins CD43 and P-selectin glycoprotein ligand 1 (CD162), respectively. CD43 expressed in COS cells supported increased binding to immobilized sialoadhesin. Finally, sialoadhesin bound different glycoforms of CD43 expressed in Chinese hamster ovary cells, including unbranched (core 1) and branched (core 2) O-linked glycans, that are normally found on CD43 in resting and activated T cells, respectively. These results identify CD43 as a T cell counterreceptor for sialoadhesin and suggest that in addition to its anti-adhesive role CD43 may promote cell-cell interactions.

Siglec‐1 inhibits RSV‐induced interferon gamma production by adult T cells in contrast to newborn T cells

“…T cells from mice lacking CD43 are able to bind Siglec‐1, which suggests that in mice another receptor may also be involved 28. However, in humans only human CD43 has been proposed as the main receptor for Siglec‐1 27. We show that the expression of CD43 is lower on newborn naïve CD4 + T cells compared to adult naïve CD4 + T cells.…”

“…Our data indicate that the presence of memory CD4 + T cells is required for Siglec‐1 to have an inhibitory effect on RSV‐induced IFN‐γ release. CD43 is a highly sialylated receptor on T cells and has been identified as the major receptor for Siglec‐1 27. T cells from mice lacking CD43 are able to bind Siglec‐1, which suggests that in mice another receptor may also be involved 28.…”

Costimulation of Host T Lymphocytes by a Trypanosomal trans-Sialidase: Involvement of CD43 Signaling

“…TS and its enzymatically inactive catalytic domain also protect the PC12 neuronal cell line from apoptosis (39). Several ligands have been proposed for CD43, including ICAM-1 (40), galectin-1 (41), class I MHC (42), E-selectin (43), and macrophage sialoadhesin (44). Our studies suggest that TS is a microbial ligand for CD43, potentially involved in pathological effects of the infection.…”

A macrophage marker, siglec‐1, is increased on circulating monocytes in patients with systemic sclerosis and induced by type i interferons and toll‐like receptor agonists

“…Therefore, it is thought to extend beyond the glycocalyx to facilitate adhesion to sialic acid-containing glycoproteins or glycolipids (34,35). Siglec-1 binds preferentially to neutrophils, but also binds CD43 on activated T cells and may also be involved in adhesion to monocytes (34)(35)(36)(37). Recently Siglec-1 has also been shown to bind to mouse macrophage galactose-type C-type lectin 1 (38).…”