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Melanie Cole (Host): Welcome. Our topic today is the histocompatibility testing for organ transplantation, and here to tell us about UAB's Histocompatibility Lab are my guests, Dr. Zhuo Tao, she's the Associate Director of Histocompatibility Immunogenetics Laboratory at UAB, and Dr. Vera Hauptfeld, she's the Director of the Histocompatibility Immunogenetics Laboratory at UAB. Welcome to the show, ladies. Dr. Hauptfeld, I'd like to start with you. Explain a little bit about the field of histocompatibility. What is the evolution of this fascinating field of study? Tell us a little bit about what you do.

Dr. Vera Hauptfeld, PhD (Guest): It's really nice to be here. The histocompatibility field is relatively new science and and still rapidly revealing. It all started with mice. A lot of things start with mice in our field, with dancing mice, and with different coat color mice. A retired teacher in Massachusetts started to breed them on a large scale to sell them to schools circuses and laboratory. At one time she noted that some mice developed skin lesions and she sent one such mouse to a pathologist at the University of Pennsylvania. He was at that time a well-known scientist who experimented with skin transplant and he diagnosed it as a tumor. Now when these tumor cells were transplanted to other mice, they noted that there was a clear difference in mice survival on which type of mice it was injected. The reason for that is that as the traits, when they were bred for, led into inbreeding. So the teacher and the pathologist embarked on a joint project investigating influence on the tumor incidents and the skin graft injections. That is where the genetics and immuno-response come together as one field, immunogenetics. And genes involved in organ, tissue, skin rejection are histocompatibility genes. Products of these genes are histocompatibility antigens which are called HLA in humans. So that's a very short story on life.

Melanie: So then tell us, Dr. Hauptfeld, I'm sticking with you for a minute. Is the work that you're doing an exact science? What strategies do you employ to make determinations as you've discussed about how everything kind of gets started with mice. Is this considered an exact science?

Dr. Hauptfeld: Yes it is. Histocompatibility antigens are a genetic determined, inherited from both parents and co-expressed on the cell surface. So to determine the HLA type of each person, we use molecular techniques based on amplifications of these genes by PCR methods. Very exact. Methods for the detection of antibodies is less exact but we have been using these methods for years, and we know pitfalls, they have been improved, and they are now so much better, accurate then a few years ago.

Melanie: Wow, it really is an absolutely fascinating field that you're in. Dr. Hauptfeld, highlight for us some of the work done in the HLA lab in support of the transplant program at UAB. Tell us a little bit about the tests and the role of HLA in transplant immunity.

Dr. Hauptfeld: The biggest obstacle to a successful organ transplant from the immunologist's point of view is a presence of pre-formed antibodies to these HLA antigens. Patients can get sensitized to produce the antigen the antibodies by transfusions, by pregnancies, and of course by previously rejected organ transplants. If we transplant across some of these strong antibodies to the donor, the organ is hyper acutely injected, which would mean for the kidneys to turn black in or, and this is exactly what we need to prevent.

Melanie: Dr. Tao, since we haven't gotten to you too much, tell us about testing recipients after transplant to monitor for rejection, and is this involved in other cellular immune mechanisms that affect the transplant recipients?

Dr. Zhuo Tao, MD (Guest): Yes. Once the patient receives a transplant, he or she becomes sensitized and will be monitored for possible rejection. We as a lab, Histocompatibility Lab, perform tests using current technology for newly developed HLA antibodies against the transplanted organ, we call these antibodies DSA, donor specific antibodies. And antibody mediated rejection is one of the major issues for transplants- organ transplant outcomes. And if DSA is identified, we will alert the physicians for appropriate immunosuppression and follow up with more tests to monitor the effectiveness of the treatment.

Melanie: So that's pretty much after transplant. And Dr. Tao, what about prior to transplant as far as running a risk assessment for patients and donors to test for this compatibility? Kind of run down for us a little bit about from start to finish to what you just discussed as far as after testing the recipients and after transplant. Give us a little timeline of how it works.

Dr. Tao: This will be a long process. Once a patient is identified as a transplant candidate, and they will get listed on UNOS wait list, and we start testing the patient- the recipient's HLA antigens and we will also test the potential donor's HLA and see how well they are matched, that’s number one.

Number two, and we will have the patient's serum which contains antibodies if it pre-exists, we will use the patient's serum cross match with the donor’s cells using flow cytometry and to see if they react to each other. And if we have no antibodies tested- previously existing antibodies- tested against the donor and cross match is Negative, this transplant will be a go.

Melanie: You mentioned UNOS, Dr. Tao. Is UNOS involved- I mean if someone gets on a transplant list, then that's what they do, but is UNOS involved in your work, in your cross matching and your testing?

Dr. Tao: Yes, it is. UNOS is one of the regulatory agencies governing the transplant programs and histocompatibility labs along with CMS, FDA, and OSHA. And UNOS is involved in many aspects of the organ transplant and donation process, and they manage, as I mentioned, the national transplant wait list, and matching the donor to the recipient, and they develop policies that give all patients a fair chance to an organ transplant. And they also maintain all the organ transplant data in the US, and they will monitor every and each organ match to ensure organ allocation policies are followed, and so on. Everything is about UNOS.

Melanie: Wow, that sounds like a lot of paperwork. So Dr. Hauptfeld, is there a difference between a workup for solid organ transplants or BMT/HSC?

Dr. Hauptfeld: Yes, there is. A workup for bone marrow transplant and hematopoietic stem cells , it's quite a difference from solid organ transplant. For solid organs, we really do not match HLA antigen. We do if we can, like relatives, siblings especially , but it's usually not possible because we don't have enough donors. For bone marrow, the HLA matching has to be done at much higher levels. Actually, exactly at the level as the antigens are expressed on the surface, which means what we call high resolution. They have many more numbers to the antigen. The reason for that is because they are immunocompetent and they can work donor versus host and host versus graft.

So they are very much more selected. But again, they are relatively much easier to find a match because we can tap into the Registries of volunteers there are really hundreds of thousands now, everywhere from America, Europe, Asia, and we have access to that. That is from these places.

Melanie: Wow, that's amazing. So Dr. Tao, are there some limits as we're discussing bone marrow and hematopoietic stem cell transplants, are there some limits you'd like to discuss? Things that might limit the results that you get, or your ability to predict the outcomes of this HLA testing?

Dr. Tao: As far as bone marrow transplant, as Dr. Hauptfeld mentioned, we type them, patient and donor at a very high level of resolution using the DSA techniques. With the new technology we are able to test to the point of very high resolution. The downside of this is we are probably having a harder time to find an exact match. So we have to select what level of the match between the donor and the recipient. With the predication, the current technologies we have many tools to provide risk assessment for our transplant programs, but every method has its limits. For example, the single antigen bead that we use so much nowadays, this is a newly developed technology that enables us to detect presence of donor specific antibodies, but unfortunately HLA is a highly polymorphic system. There are close to 9,000 of Class I antigen variants and over 2,600 Class II antigen variants. That's the count of 2014, and this number continues to grow every day. But the single antigen bead panel has beads coated with about 100 common Class I antigens and about eighty Class II antigens. In other words, if a patient has an antibody that's not presented on the single antigen bead panel, we won't be able to detect it.

And the other limitation that I wanted to mention is we test for antibodies against major HLA antigens. At this time there's not a well-developed commercially available and easy-to-use reagent to test minor HLA antibodies or non-HLA antibodies, and those antibodies could also cause organ rejection.

Melanie: So much information. Dr. Hauptfeld, what's it like to work in this lab? As you're pretty much the final say in going ahead with a transplant, and you keep such a close eye on donor and recipient and these antigens and matching. So what's it like for you to be able to be this final say in something that could be so huge in someone's life?

Dr. Hauptfeld: Yes. We are really very much aware that [if we are not careful enough, we can kill a patient. Everyone in the laboratory is aware of it. You know, this is not work of 'I,' it's the work of 'we.' Everyone in the laboratory is involved and has to do their best. So our work is challenging and it's stressful, but it is also very rewarding. We actually see some of these patients once a year at a picnic, and it is extremely soul lifting to see how well they are doing. They are- so we are helping patients to have better lives and that keeps us going.

Melanie: Dr. Tao, if you were to look forward ten years in the field, what do you feel will be some of the most important areas of research?

Dr. Tao: We would like to see better long-term organ transplant survival. Organ survival as well as patient survival. We're now looking at molecular levels of differences between the patient and the donor histocompatibility antigens, relating them to presence and absence of anti-donor antibodies for the transplant before and after. And also the goal would be to define permissive difference which would not lead to rejections or at least to prolong the survival. We don't have- for solid organs, we don't have enough donors to choose from, and cannot select a good enough match, and we= the science says the better the match, the better the outcome. so defining possible mismatches, it will be much easier. We call it permissive mismatch. We also wanted to see more donations in general. Each donated organ saves a life, and this is truly, truly a fantastic experience to see how much better off the patient is after a transplant.

Melanie: Dr. Hauptfeld, in summary, tell other physicians what you would like them to know about the Histocompatibility Lab at UAB, when to refer, or when you want them to look to you for your expertise.

Dr. Hauptfeld: This is a great question. We don't get referred from anywhere else. We are part of the transplant program, so we have what we call a joint agreement with every program there is. There's a children's hospital Veteran’s-Veteran’s Hospital, and UAB, all solid organ, heart, lung , and so forth. And so they know precisely what we are going to do for them. So every patient that is listed just comes to us. Oh not the patients, we don't see patients, but the proper samples so we can test for their antigens and antibodies and so forth. We monitor them throughout their waiting time, and so that is one thing that we need to get serum samples on a regular basis, but that is already established and UNOS has hands in it, too. So we are getting and following them for the presence of antibodies, till they come for the transplant, and what actually I think would be better developed follow-up for the possible rising of the anti-donor specific antibodies, then we will get their serum samples more often. Not that we want more work, we already have plenty of work, but I think for the patient it would be really better if we see them every six months. Because when we see the arising DSA, the donor specific antibodies, we can alert the team, and tell them what needs to be done, and if it's necessary to start to treat the patient or just monitor the patient. But if we see the patient after two or three years, the antibodies are really, really strong that it's so much harder to save the transplanted organ. So I think that’s really basically what we know.

Also we would like to have good information about all sensitizing events. Because sensitizing events are interfering with our tests and if we don't know about them, we spend much more time trying to figure out what's going on. Like that we can plug it into the results and see what’s really going on and have better interpretation.

Melanie: And that would certainly help you explain and sort out any unexpected results. So Dr. Hauptfeld, here I would like for you to tell us about your team at UAB, and why is your team so great to work with?

Dr. Hauptfeld: I'm really proud of my team. I mean we have great people, we have great hard-working people who really want to help, and they are very much aware they are helping. And so as for the laboratory, it's really great. But also, I love to work with our surgeons who are smart, very innovative people, with nephrologists, with cardiologists, and they are appreciative of our work, we are appreciative of their work, and I think they are fantastic clinicians. Obviously, I mean we have very great outcomes here at UAB.

We have one of the best KPD programs, the kidney pair donation program, to supplement the shortage of deceased donors which is really great. The shortage is great, we really would like to improve it. But our KPD was set up several years ago by Dr. Locke, and I think that this is fantastic, and we can match, and we can actually play in some way to match as best as we can as we are moving the possible donors and patients around. So they have the best of everything, and I am really very proud of it and happy.

Melanie: Dr. Tao, last word to you, what do you love about your team and working at UAB?

Dr. Tao: Oh, we have a great team. Our technologists are all trained to work as a team. This is the only way to provide a best service to our transplant program, and there's only one histocompatibility lab in the state of Alabama, and it is a privilege to work with the UAB transplant program. And UAB had their very first- or our very first transplant in Alabama in 1968, which was a kidney transplant, and we had the very first heart transplant in Alabama in 1981. And the very first combined heart and lung transplant in '86. And we reached our 10,000th organ transplant in 2006. This is such a great program and we have the best doctors and one of the best kidney pair donation programs in the nation. So I have very, very good experience. It's just fantastic.

Melanie: Wow, ladies, what an absolutely fascinating segment, and what you both do is so interesting and complicated and comprehensive that it's hard for a lot of people to understand, but you've made it so clear today. Thank you so much for being on with us. A community physician can refer a patient to UAB Medicine by calling the MIST Line at 1(800) UAB-MIST. That's 1(800) 822-6478. You're listening to UAB MedCast. For more information on resources available at UAB Medicine, you can go to www.UABMedicine.org/physician. That's www.UABMedicine.org/physician. This is Melanie Cole, thanks so much for listening.