October 28, 2024, Immune Tolerance
Receiving a kidney transplant is a rare opportunity given the severe shortage of donor kidneys.
Faced with this precious opportunity, many patients with uremia grapple with the following questions:
- Does it matter if this kidney is a match for me?
- Can a kidney transplant still be performed if the matching result is “poor”?
- Can we wait for the matching results before proceeding with the transplant?
During this spring season, Dr. Wang would like to discuss the above questions with you:
What Are HLA and HLA Matching?
Let’s discuss what HLA is and what HLA matching entails.
The full name of HLA is “human leukocyte antigen,” which reflects the immune compatibility between two individuals. In organ transplantation, it indicates the degree to which the patient accepts the transplanted organ.
Aside from identical twins, whose HLAs are identical, no two people’s HLAs are exactly the same, making HLA akin to an individual’s “identity card.” After surgery, the transplanted organ will not be rejected even without taking immunosuppressive drugs.
However, because HLA has numerous loci, and some have minimal impact on kidney allograft rejection, only a few critical loci are typically tested clinically.
Since each individual inherits one set of chromosomes from each parent, clinical testing focuses on three loci per set—HLA-A, HLA-B, and HLA-DR—resulting in six loci across both sets of chromosomes.
The Relationship Between HLA Matching and Kidney Allograft Rejection
HLA is a key factor in determining the risk of kidney transplant rejection. The greater the number of matching HLA loci between the donor and recipient, the lower the risk of kidney transplant rejection and the higher the long-term survival rate of the transplanted kidney. Because identical twins share identical HLAs, their transplanted organs would not be rejected even without immunosuppressive drugs.
Because numerous factors can influence kidney allograft rejection and its long-term survival—such as insufficient doses of immunosuppressive drugs, drug toxicity, kidney viral infections, and recurrence of glomerulonephritis in the allograft—HLA matching does not play a decisive role in the long-term survival of kidney transplants.
HLA Matching and the Timing of Kidney Transplantation
Since HLA matching also influences the long-term outcomes of kidney transplants, why are transplants sometimes performed before the matching results are available?
In living related kidney transplantation, with sufficient preparation time, it is indeed feasible to perform the transplant after obtaining HLA matching results. However, in donation after circulatory death (DCD) kidney transplantation, due to limited preparation time, it is challenging to wait for HLA matching results to minimize the cold ischemia time of the transplanted kidney. Additionally, HLA matching results are not mandatory for kidney transplantation, so in many cases, these results are determined after the transplant.
The Relationship Between Blood Type, HLA Matching, and Kidney Transplantation
Dr. Wang frequently employs this informal analogy to explain the relationship between blood type, HLA matching, and kidney transplantation:
A kidney transplant is akin to two people getting married, where blood type resembles gender, HLA matching resembles physical appearance, and the long-term survival of the transplant mirrors the duration of the marriage. As long as gender (blood type) is compatible, whether the appearance is unattractive or attractive (HLA matching results) does not hinder the ability to marry (undergo a kidney transplant). Numerous factors influence the longevity of a marriage (kidney transplant survival), and a more attractive spouse (better HLA match) is likely to contribute to a longer-lasting relationship. Kidney transplants with incompatible blood types are now well-established, just as individuals with conflicting genders can marry, so blood type (gender) no longer poses a barrier to marriage (kidney transplantation).
Written by | Wang Jina
