RECIPIENT MONONUCLEAR CELL RECOGNITION AND ADHESION TO GRAFT ENDOTHELIUM AFTER HUMAN CARDIAC TRANSPLANTATION - LYMPHOCYTE RECOGNITION LEADSTO MONOCYTE ADHESION

Transendothelial migration of mononuclear cells is crucial in the deve lopment of allograft rejection and transplant coronary disease. Adhesi on of circulating cells to endothelium is the initial step in transend othelial migration. Human aortic endothelial cell cultures were establ ished from aortic tissue harvested at the time of organ donation for c ardiac transplantation which allowed specific recipient mononuclear ce ll-graft endothelial interactions to be studied. Confluent untreated e ndothelial cells were incubated with recipient mononuclear cells for 1 5 min to assess adhesion. Adhesion of recipient mononuclear cells to e ndothelium derived from their graft was threefold higher than adhesion to nonspecific endothelium (93+/-20 vs. 30+/-11 cells/high power fiel d, P < 0.005). Graft-specific adhesion was inhibited by preincubation of the endothelium with antibodies to class I HLA (34+/-16 cells/high power field, P < 0.005). Immunofluorescence performed after adhesion s howed that 73+/-6% of both specific and nonspecific adherent cells wer e monocytes. The use of purified lymphocyte and monocyte preparations showed that graft-specific lymphocytes induce unrelated monocytes to b ecome adherent, These results suggest that lymphocytes are primed in v ivo to recognize endothelium derived from their graft which leads to a rapid increase in lymphocyte and monocyte adhesion. Such allo-recogni tion may involve endothelial class I HLA molecules.