written by
Harvey Mysel

"Matching" and Kidney Transplants - Myths and Misconceptions

2 min read , December 4, 2020

The use of the terms “match,” “matching,” or a “perfect match” are often misunderstood or misused when referring to a recipient and donor.

A more accurate way of describing the evaluation process is to use the terms “suitable” and “compatible.” A suitable donor is someone healthy enough to donate. A donor is compatible when all the tests are finalized for the recipient and donor, and it is shown that the prospective donor can donate to their recipient. When people say they are a "match," they usually mean that they are compatible with the recipient.

Generally, a recipient and donor aren't "matched" until they know that the donor is suitable and compatible.

The term “match” references the 6 HLA's (Human Leukcyte Antigens.) Before antirejection medications, 6 out of 6 antigens needed to match for the transplant to be successful. The new anti-rejection drugs are so effective that there isn’t a statistical difference in success rates between a zero match and a 5 out of 6 matches. Therefore, HLA matching typically is not a factor that determines whether someone is compatible. There is, however, a benefit to having a “perfect match,” 6 out of 6 antigens, since the life of the transplanted kidney survives significantly longer. (On average, 28 years instead of 18 years for a 0 - 5 match,)

Donor and recipient matching is divided into three distinct areas: blood type matching, tissue type matching (the HLA referenced above,) and cross-matching.

Transplants are being done when donor and recipient have different blood types. A procedure called plasmapheresis on the recipient makes this possible. (Plasmapheresis will be a topic of another blog.)

Cross-matching is a very sensitive and final test performed on a kidney donor and their recipient. The basic cross-match test involves a mixing of the donor's and recipient's cells and serum to determine whether or not the recipient of a kidney will respond to the transplanted organ by attempting to reject it. A positive crossmatch means that the recipient has responded to the donor and that the transplant should not be carried out. A negative crossmatch means that the recipient has not responded to the donor, and therefore transplantation should be safe.

While this language may appear a bit backward, the cross match is the test indicating a “go” or” no go” for the transplant.

Either way, hearing that there's a "match" is usually Great News!!

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