Evidence for an immunoregulatory role of OX2 with its counter ligand (OX2L) in the regulation of transplant rejection, fetal loss, autoimmunity and tumor growth.

Transplantation has emerged as an effective treatment for patients with end-stage organ failure. Current regimens of non-specific immunosuppressive drug treatment, which are needed life-long to prevent graft rejection, have numerous adverse side effects and increase the risk of opportunistic infections and malignancy. A major goal is to develop immunotherapeutic protocols that achieve specific tolerance. Such protocols would decrease and eventually eliminate the reliance on non-specific drug therapy. We showed that portal vein delivery of donor antigen prolongs the survival of vascularized and non-vascularized allo- and xeno-grafts, and that increased graft survival is associated with altered cytokine production and augmented expression of the molecule OX2. This review documents further evidence for a more general immunoregulatory role for the interactions of OX2 and its ligand, OX2L.