COMPARISON BETWEEN AORTIC AND SINUSOIDAL LIVER ENDOTHELIAL-CELLS AS TARGETS OF HYPERACUTE XENOGENEIC REJECTION IN THE PIG TO HUMAN COMBINATION

Endothelial cells of aortic origin are usually used in vitro as target s of hyperacute xenogeneic rejection, although endothelial cells from organs may have different properties. The sensitivities of aortic and liver endothelial cells to hyperacute xenogeneic rejection were compar ed in the pig to human combination. Sinusoidal liver endothelial cells were isolated and purified by collagenase perfusion of pig livers, se dimentation on a percoll gradient and selective adherence. Purity and viability of isolated liver endothelial cells after adherence were 85/-6% and >95%, respectively, Endothelial cells from pig aortae (purity and viability >95%) were isolated by scraping. Immunoblotting analysi s of xenoantigens on liver and aortic endothelial cell membranes prepa rations showed identical patterns, The strongest bands revealed by hum an IgM were located between 110 and 135 kD, while human IgG detected t wo major bands at 115 and 75 kD. The membrane expression of xenoantige ns recognized by human sera, analyzed by flow cytometry, was significa ntly lower on liver than on aortic endothelial cells (IgM P=0.006; IgG : P=0.009). However, the complement-dependent cytotoxic activity of hu man sera was the same whether liver (54.5+/-1.4%) or aortic endothelia l cells (50.0+/-4.2%) were used as targets. Taken together, those resu lts allow the use of aortic instead of sinusoidal liver endothelial ce lls in the characterization of-pig antigens recognized by human natura l antibodies.