ADHESION MOLECULES AND TRANSPLANTATION

Objective Accessory adhesion molecules are thought to influence the fi rst interaction between host leukocytes and graft vascular endothelial cells. Their role in transplantation is reviewed. Summary Adhesion mo lecules have been divided into three major families: the selectins, th e integrins, and the immunoglobulin superfamily. Selectins are small p roteins that mediate the first contact between stimulated endothelial cells and leukocytes. Integrins interact with cytoskeletal components of cells, presumably coordinating extracellular stimuli with cytoskele ton dependent actions, such as motility, shape change, and phagocytic responses. Members of the immunoglobulin superfamily are structurally homologous, although they do not necessarily share similar functions. They are involved in T-cell proliferation and intracellular events. Me thods Various groups of investigators have studied the influence and e xpression of adhesion molecules following transplantation. The authors of this article have reviewed and summarized the available literature . Results Many different adhesion molecules are up-regulated during th e rejection event. Treatment of transplant recipients with monoclonal antibodies against accessory molecules, such as leukocyte function ass ociated antigen 1 (LFA-I) and intercellular adhesion molecule 1 (ICAM- 1), has resulted in either a prolongation of transplant survival or th e induction of tolerance in some models. Other interventions are under study. Conclusion By mediating the initial leukocyte/endothelial cell interactions, adhesion molecules may play an important role in graft rejection, mediation of infiltration into the graft, and dissemination of the antigenic message to the lymphoid tissues of the host. Future studies will have to deal not only with conceptualizing their function and mechanisms of action, but also with manipulating their interrelat ionships to the benefit of the graft recipient.