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Cardiac allograft vasculopathy: relationship with acute cellular rejection and histocompatibility
1Department of Medicine, Loyola University of Chicago, Maywood, IL 60153.
Insights
Complete HLA-B and -DR mismatch in heart transplants is linked to increased rejection, severity, and mortality. A trend suggests higher cardiac allograft vasculopathy incidence with HLA-DR mismatch.
Area of Science:
- Immunology
- Transplantation Medicine
- Cardiology
Background:
- Cardiac allograft vasculopathy (CAV) is a major cause of late graft loss after heart transplantation.
- The relationship between histocompatibility, rejection, and CAV is complex and has yielded conflicting results in previous studies.
- Current diagnostic methods for CAV, like angiography, may underestimate its prevalence and severity.
Purpose of the Study:
- To review existing literature and present data on the association between histocompatibility, rejection, and cardiac allograft vasculopathy.
- To evaluate the impact of specific human leukocyte antigen (HLA) mismatches on rejection and CAV development.
- To identify areas for future research in understanding and mitigating CAV.
Main Methods:
- Review of retrospective studies and data from Loyola University of Chicago.
- Analysis of the relationship between rejection and CAV.
- Evaluation of the impact of histocompatibility (HLA matching) on CAV.
- Assessment of diagnostic limitations and variability in immunosuppressive regimens.
Main Results:
- Conflicting results exist regarding the link between rejection and CAV, and histocompatibility and CAV.
- Complete mismatch at the HLA-B and -DR loci is associated with higher rejection rates, increased severity, and greater mortality.
- A trend indicated a higher incidence of CAV in patients with complete HLA-DR locus mismatch.
Conclusions:
- Complete HLA-B and -DR mismatch correlates with adverse outcomes in heart transplant recipients.
- Further research using molecular tissue typing is needed to clarify the role of histocompatibility in CAV.
- Development of novel immunosuppressive strategies is crucial to overcome tissue incompatibility challenges in heart transplantation.
Abstract:
This article reviews the literature and summarizes the data obtained at Loyola University of Chicago about the relationship between rejection, histocompatibility, and cardiac allograft vasculopathy. Both the studies concerning the relationship between rejection and cardiac allograft vasculopathy and those evaluating the impact of histocompatibility on cardiac allograft vasculopathy have produced conflicting results. Most studies are retrospective and include a small number of patients followed up for short periods of time and treated with variable immunosuppressive regimens. In addition, the diagnosis of cardiac allograft vasculopathy is based on angiographic detection of coronary arterial abnormalities, a method that is known to underestimate the presence and severity of cardiac allograft vasculopathy. The ability to assess the impact of histocompatibility on the development of cardiac allograft vasculopathy is also limited by the lack of uniformity in the type and number of HLA variables analyzed, the extreme polymorphism of the HLA antigens and variability in serologic tissue typing techniques and quality. The results of our study suggest that complete mismatch at the HLA-B and -DR loci is associated with higher rejection rates and severity and with increased mortality. We also noted a trend toward a higher incidence of cardiac allograft vasculopathy in patients with complete mismatch at the HLA-DR locus. Future experimental and clinical studies should be done with use of molecular tissue typing techniques to further elucidate the impact of histocompatibility on cardiac allograft vasculopathy. The role of non-HLA antigens in the development of cardiac allograft vasculopathy requires further definition. Because in heart transplantation the short donor ischemic times compatible with a successful outcome limit the feasibility of prospective donor/recipient tissue typing, the development of immunosuppressive drugs that effectively reduce the detrimental effects of tissue incompatibility is crucially needed.