What is cPRA and What Role Does It Play in Kidney Transplants?

Matt Ronin, VP of Research & CMC Operations

If you are a candidate for a kidney transplant, you may have heard the term cPRA. Here’s what that term means and how it relates to your ability to find a suitable kidney donor.

In transplants, cPRA, which stands for calculated panel reactive antibody, is a score that indicates the patient’s degree of medical compatibility with a large pool of donors. Basically, it is a measure used to assess the likelihood of finding an organ donor.

For example, if a patient has a cPRA of 25 and they are matched against a pool of 100 potential donors, in general, 25 out of the 100 potential donors will not be a match for the patient and 75 will match to some degree. A cPRA of 25 is relatively low and is not considered difficult to match. A cPRA of 98, for example, is significantly more challenging to match, though a match is still possible through paired exchange, even for patients with a cPRA of 99.9. The wait time to find a match might just be a bit longer.

How is cPRA calculated?

Panel reactive antibodies (PRA) are proteins produced by the recipient’s immune system in response to foreign substances, such as those found in a donor organ.

The cPRA score is calculated based on the recipient’s antibody reactivity against a panel of human leukocyte antigens (HLA), which are proteins found on the surface of cells. The higher the level of reactivity against these antigens, the higher the cPRA value.

Medical professionals use this value to assess the likelihood of finding a compatible donor for a kidney transplant. The cPRA essentially estimates the percentage of donors a kidney patient would be compatible with. Patients with high cPRA scores are compatible with fewer potential donors. Conversely, patients with low cPRA scores are likely to be compatible with a larger number of donors.

It is important to note that the cPRA score is not used to measure medical compatibility between a kidney transplant candidate and a specific potential donor; it is simply a way of estimating how easy or difficult it will be to find a well-matched donor for a specific kidney transplant candidate.

Why is cPRA important in kidney transplants?

cPRA plays a crucial role in determining the compatibility between a transplant candidate and potential kidney donors. A high cPRA value indicates that the recipient has a high level of antibodies against potential donors, making it more challenging to find a suitable match. This can significantly impact the likelihood of a successful transplant and increase the risk of rejection.

For individuals in need of a kidney transplant, understanding their cPRA value is essential in determining the feasibility of finding a suitable donor. A higher cPRA value may indicate a longer wait time for a transplant, as finding a compatible donor becomes more challenging.

In some cases, patients with high cPRA values may require alternative treatment options, such as desensitization therapy, to improve their chances of a successful transplant.