Lectin ligands on human dendritic cells and identification of a peanut agglutinin positive subset in blood

As only a few cell surface markers for dendritic cells (DC) have been ident ified to date, this study examined the expression of ligands for lectin on different human DC populations. The ability of Concanavalin A (Con A), Whea t Germ Agglutinin (WGA), peanut agglutinin (PNA), and Helix pomatia (HPA) t o bind to cell lines and PBMC and DC populations was analyzed by dow cytome try and specificity of binding confirmed using inhibitory and noninhibitory sugars. The cell Lines showed non-lineage-restricted binding with Con A an d WGA independent of sialidase treatment. HPA and PNA bound to a restricted number of lines, but showed broad reactivity after sialidase treatment. Th e peripheral blood mononuclear cells (PBMC) and directly isolated blood DC, activated CD83(+) blood DC, epidermal Langerhans cells (LC), and monocyte- derived DC (Mo-DC) showed strong binding of Con A and WGA, both before and after sialidase treatment. No DPA binding ligands were detected on PBMC pop ulations, including directly isolated blood DC. Following sialidase treatme nt CD3(+), CD16(+), and a subset of CD19(+) lymphocytes bound DPA The lecti n PNA bound weakly to CD14(+) monocytes and a subpopulation of circulating DC that were HLA-DR(hi)CDw123 Dr(hi)CDw123(dim)/(neg)CD11c(+). The HLA-DR(m od)CDw123(hi)CD11(neg) subpopulation did not bind PNA Without sialidase tre atment LC expressed both HPA and PNA Ligands, but these were either absent on activated CD83(+) blood DC or weakly expressed on Mo-DC. Following siali dase treatment PBMC populations, activated CD83(+) blood DC, and Mo-DC beca me PNA positive. Thus human DC express several lectin ligands and PNA bindi ng identifies a subset of blood DC. That may reflect discrete changes assoc iated with stages of DC development or functional maturation. (C) 2000 Acad emic Press.