Tissue Matching and Organ Rejection

Donor to recipient tissue match is a major determinant of post-transplant success.  Nine percent of heart transplant mortality is linked to rejection of the donor heart by the recipient’s immune system and patients with more than two HLA-DR mismatches have a 19% risk of organ rejection one year following the transplant.

Analyzing heart transplant rejection and survival.

There is direct relationship between the donor and recipient major histocompatiblity complex (MHC) marker antigens and survival in heart transplantation.  Human leukocyte antigens (HLA) on the surface of the donor organ are the primary targets of cellular-based rejection. The similarity (or dissimilarity) of the donor and recipient tissue is measured as an HLA-mismatch for six HLA class I and II antigens (A, B, and DR).

Survival in heart transplantation has primarily been associated with graft cold ischemic time and immediate surgical and post-operative complications.  However, as surgical and organ preservation techniques have improved, tissue matching has become a determining factor in long-term outcomes of heart transplant recipients.

As documented in a multi-center trial from UNOS Scientific Registry data, there was an increased risk of mortality with the increasing number of tissue mismatches.  The HLA-DR locus is exceptionally important and tissue matching could ‘improve survival by 9% and decrease the number of rejection episodes by 19%.’   Unfortunately, the chance of a complete tissue “match” by random donor organ is 1.5%, however when examining all the potential donors east of the Mississippi River in the United States then 94% of the recipients have at least four HLA matches (of the six possible). Because of the improvement in long-term survival; HLA tissue matching should be considered as an additional criteria for recipient selection.

Reperio can be used by transplant centers, histocompatiblity laboratories and surgeons to independently evaluate transplant recipients HLA matching to determine the relationship between survival and graft compatibility.  This software is validated against UNOS data.