High-level porcine endothelial cell expression of alpha(1,2)-fucosyltransferase reduces human monocyte adhesion and activation

Background Monocyte binding to and activation by human endothelium requires a number of interactions, including those involving sialylated endothelial cell ligands. As porcine endothelial cell transfection with alpha(1,2)-fuc osyltransferase has been shown to reduce terminal sialylation, we investiga ted whether high-level expression of alpha(1,2)-fucosyltransferase by porci ne endothelium would reduce human monocyte adhesion and functional activati on. Methods. Purified human monocytes were labeled with Cr-51, and measured for adherence to human or porcine endothelial cell monolayers in the presence of either medium or monoclonal antibodies against monocyte lectins or sialy lated endothelial cell ligands. Monocyte production of prostaglandin E2 (PG E2) and interleukin-1 beta (IL-1 beta) was measured by enzyme-linked immuno sorbent assay, using supernatants collected from cultures performed between human monocytes and human or porcine endothelial cell monolayers. Finally, monocyte adhesion and activation were measured after culture with a porcin e endothelial cell line transfected with alpha(1,2)-fucosyltransferase, exp ressing reduced surface expression of terminal Gal alpha(1,3)-Gal and siali c acid residues. Results. Human monocytes adhered by 50% higher levels to porcine endotheliu m than to human endothelium. This increased level of adherence was associat ed with augmented monocyte activation, as defined by 3.3-fold higher levels of PGE2 production and 7.3-fold higher levels of IL-1 beta production. Mon oclonal antibodies against CD62L (L-selectin) on monocytes or CD15s (sialyl ated Lewis X) on porcine endothelium reduced monocyte adhesion by 38% and 5 2%, respectively. Porcine endothelial cell transfection with alpha(1,2) -fu cosyltransferase reduced terminal sialic acid expression by 65%, monocyte a dherence by 50%, and the production of PGE2 and IL-1 beta by 67% and 38%, r espectively. Conclusions. Together, these results demonstrate that human monocytes use s urface lectins to bind to sialylated carbohydrate structures on porcine end othelium, and indicate that reduction in porcine endothelial cell surface e xpression of terminally sialylated structures by high-level alpha(1,2)-fuco syltransferase activity reduces monocyte adherence and activation.