Expression of adhesion molecules and their ligands in liver allografts during cytomegalovirus (CMV) infection and acute rejection

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Abstract
Vascular adhesion molecules and their ligands are important in leukocyte-endothelial cell interactions and in T-cell activation of rejection cascade. Also, cytomegalovirus (CMV) infection is suggested to be involved in the mechanisms of rejection. In this study, the expression of vascular adhesion molecules ICAM-1, VCAM-1 and ELAM-1 in the liver allografts, the number of leukocytes positive for their ligands LFA-1, VLA-4 and SLex, and activation markers (class II, IL2-receptor) were investigated in liver allografts during CMV infection and acute rejection and compared to grafts with normal function and histology. The adhesion molecules, their ligands and activation markers were demonstrated from liver biopsy frozen sections by the immunoperoxidase technique and monoclonal antibodies. A significant induction of ICAM-1 and VCAM-1 was seen in vascular and sinusoidal endothelium associated with both CMV and rejection, and induction of ELAM-1 in vascular endothelium in rejection only. In both cases, the number of leukocytes expressing LFA-1 was significantly increased, but VLA-4-positive cells were more characteristic for CMV and SLex-positive cells more for rejection. IL2-receptor positivity was practically seen in rejection only, but class II-expressing cells were increased during both CMV infection and rejection. In conclusion, adhesion molecules were induced and the infiltrating cells expressed their ligands both in liver rejection and during CMV infection, although the expression pattern was slightly different.