HUMAN VASCULAR ENDOTHELIAL-CELLS PROCESS AND PRESENT AUTOANTIGEN TO HUMAN T-CELL LINES

The effectiveness of cultured human umbilical vein endothelial cells a s accessory cells for T cell activation has been investigated using T cell clones and lines derived from patients with myasthenia gravis whi ch were specific for different epitopes on the a subunit of the human acetylcholine receptor. The endothelial cells were induced with IFN-ga mma to express HLA-DR and -DQ at high and low levels respectively. The y could then efficiently present specific peptides of the alpha subuni t to an HLA-DR- and an HLA-DQw5-restricted T cell line. They could als o process epitopes for both T cell lines from the full-length recombin ant alpha subunit (r1-437) of the human acetylcholine receptor, where the known epitopes are 80 amino acid residues apart. The endothelial p resentation of rl-437, but not of the peptides, was sensitive to chlor oquine inhibition. Presentation appeared slightly less efficient (by 1 .5- to 3.0-fold) with endothelial cells than with presenting cells fro m peripheral blood. This may reflect differences in accessory signalli ng since mAb blocking studies suggested that ligands for CD28 provided important accessory signalling by peripheral blood presenting cells w hile LFA-3 was used by endothelial cells.