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 identified to date, this study examined the expression of ligands for lectin on different human DC populations. The ability of Concanavalin A (Con A), Wheat Germ Agglutinin (WGA), peanut agglutinin (PNA), and Helix pomatia (HPA) to bind to cell lines and PBMC and DC populations was analyzed by flow cytometry and specificity of binding confirmed using inhibitory and noninhibitory sugars. The cell lines showed non-lineage-restricted binding with Con A and WGA, independent of sialidase treatment. HPA and PNA bound to a restricted number of lines, but showed broad reactivity after sialidase treatment. The 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 HPA binding ligands were detected on PBMC populations, including directly isolated blood DC. Following sialidase treatment CD3(+), CD16(+), and a subset of CD19(+) lymphocytes bound HPA. The lectin 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(mod)CDw123(hi)CD11c(neg) subpopulation did not bind PNA. Without sialidase treatment LC expressed both HPA and PNA ligands, but these were either absent on activated CD83(+) blood DC or weakly expressed on Mo-DC. Following sialidase treatment PBMC populations, activated CD83(+) blood DC, and Mo-DC became PNA positive. Thus human DC express several lectin ligands and PNA binding identifies a subset of blood DC. That may reflect discrete changes associated with stages of DC development or functional maturation.

Role of atrial natriuretic factor in sodium and water retention in patients with schistosomal hepatic fibrosis.

Fifty subjects divided into three groups were studied: Group I: 10 normal adult subjects as controls. Group II: 20 patients with schistosomal hepatic fibrosis (SHF) without ascites (compensated stage). Group III: 20 patients with SHF with ascites. In all these patients plasma atrial natriuretic factor (ANF), serum aldosterone and serum osmolality were determined. There was a significant decrease in the plasma ANF in groups II and III compared to group I. There was a significant increase in the serum aldosterone level in group III compared to groups I and II. No significant difference was noted in serum sodium and potassium levels among the three groups. There was a significant decrease in serum osmolality in groups II and III compared to group I.

Inhibition of erythrocyte and plasma cholinesterase by 5-hydroxytryptamine.

The inhibition of human erythrocytes and plasma cholinesterase (ChE) by 5-hydroxytryptamine in vitro was studied. Constants characterising this inhibition, namely the inhibition rate for red blood cells RBCs (2.5 x 10(4) (mol/l)-1 min-1) and plasma ChE (1.08 x 10(4) (mol/l)-1 min-1) as well as the rate constant for spontaneous reactivation for RBCs (0.3 min-1) and plasma ChE (0.26 min-1) were calculated. The inhibition of RBCs and plasma ChE by 5-hydroxy-tryptamine was found to be of the competitive type.