ABO-Incompatible Kidney Transplants: Our New Titer Method

Carter BloodCare’s Immunohematology Reference Laboratory (IRL) is changing the way we do our ABO-incompatible renal transplant titer testing.  We are changing our method to better serve our hospitals and, ultimately, our community patients.

But before we get into our titer testing and how it’s done, let’s discuss why this is so important for patient care. ABO antigens are not only present on red blood cells – they are also present on organ tissues. Therefore, we have to protect the donor kidney from recipient ABO antibodies, just like we do for red blood cell transfusion. Because of this, transplanting an ABO-incompatible kidney is much more complicated than transplanting a compatible kidney – so much so, that it used to not even be possible! Blood type O patients would be (and often still are) on the kidney transplant waiting list for much longer than blood type AB patients. Remember, blood type O patients have naturally occurring anti-A and anti-B antibodies that (typically) prevent them from receiving blood type A or B kidneys.

ABO incompatible kidney transplants are now possible because there have been advancements in the transplantation process that allow doctors to decrease the naturally occurring ABO antibodies present in recipient patients. But, in order to do this, the transplant doctors need fast, real-time anti-A and anti-B titer testing to see what level these ABO antibodies are at- they need to be ready to go to surgery shortly after the antibodies have been decreased to an acceptable threshold for transplant. This is why ABO-incompatible renal transplant titer testing (let’s just call it titer testing from here on out) is an important part of preparing for an ABO-incompatible renal transplant. It helps patients to receive ABO mismatched renal transplants; a huge benefit for those patients with a more restrictive ABO organ recipient blood type.

We started providing this service to a Dallas hospital in 2015 when they began performing ABO-incompatible kidney transplants. We used an extensive series of test tubes to make multiple dilutions in order to ultimately measure the titer of the ABO antibody. But, these doctors needed their results even faster than this laborious process could provide. So, our IRL looked into how we could speed up the process. We looked at the literature and talked with other labs and found that much faster titer testing can be done by putting the multiple diluted samples on a manual gel methodology system. We tried it, and did a comparison study with our conventional tube testing- and found that the results of this method were almost identical to the tube method!

Ultimately, switching to manual gel titer testing shortened our turn-around-time from 3-4 hours to ~1 hour… meaning accurate results in a fraction of the time! We are happy to start rolling out our new gel titer methodology, and hope that this faster turn-around-time will be able to help the patients we serve get the transplants they need.

References:

Tobian AAR, Shirey RS, King KE. Editorial: ABO antibody titer monitoring for incompatible renal transplantation. Transfusion 2011; 51:454-457.

 Shirey RS, Cai W, Montgomery RA. Streamlining ABO antibody titrations for monitoring ABO-incompatible kidney transplants. Transfusion 2010; 50: 631-634.