CHARACTERIZATION OF MEMBRANE SUGAR-SPECIFIC RECEPTORS IN CULTURED HIGH ENDOTHELIAL-CELLS FROM MOUSE PERIPHERAL LYMPH-NODES

The culture of specialized high endothelial cells (HEC) from lymphoid organs (peripheral lymph nodes (PLN) and Peyer's patches (PP)) was undertaken in order to study and characterize the cell surface molecules which are involved in lymphocyte recognition and allow homing. Cells were stimulated in vivo by a graft versus host (GVH) type of reaction before isolation and culture. The resulting adherent and growing cells were characterized as endothelial cells because of their typical aspect and their ability to produce angiotensin-converting enzyme and factor VIII-related antigen. They possess tissue-specific endothelial addressins. MECA 79 antigen is present on cells isolated from PLN while MECA 367 antigen is detected on cells from PP. Surface receptors for glycans were studied cytochemically using neoglycoproteins and fluorescence microscopy and quantified by flow cytometry experiments which showed that the specificity of sugar receptors depends upon endothelial cell origin. Indeed, sugar receptors for alpha-L-fucosyl residues were specifically expressed by endothelial cells from PLN. These receptors were inducible upon action of activated lymphocyte-conditioned medium. Further characterization of endothelial cells from peripheral lymph nodes indicates. that they indeed mediate adhesion of lymphocytes in vitro. The role of protein-sugar interactions in this process was assessed by inhibition experiments performed with the help of neoglycoproteins. Best inhibitory effects were obtained when endothelial cells had been preincubated with alpha-L-fucosyl-BSA and when lymphoid cells were preincubated with beta-D-galactosyl-BSA. Concomitant inhibition assays indicate the participation of sugar specific receptors - endogeneous lectins - on the surface of both endothelial and lymphoid cells to achieve recognition and adhesion.