“What if I am not a match?” Living donor pool / incompatible transplants

Ideally the donor and recipient should ‘match’ as closely as possible in two areas – the blood group and the tissue type. Please click here to read about this in more detail. Until a few years ago if the donor was not the right blood group or the recipient had antibodies to the donor’s tissue type there was no possibility that they could donate. Now however there are two options.

Living donor pooled exchange programme

ronadlWhiteThis is a sharing scheme for living donor kidneys where they are ‘swapped’. For example, if I wanted to give a kidney to my sister but I had the wrong blood group, it may be that my kidney will suit Mrs Blogs in Scotland and that Mr Blogs (who couldn’t donate directly to his wife because of his blood group) has a kidney that would suit my sister very well (as an example see figure 1 [figure 1 page 25]). Quite often there can be two other pairs involved – a ‘3-way swap’. In NI we transplanted our first patient in this scheme in January 2010 click here for link to Belfast Telegraph story  and by summer 2014 over 30 people had successfully received a transplant in this pooled exchange programme.

If a donor and recipient pair is entered into the pool then their details are registered with the national centre in England. Four times in the year (January, April, July and October) there is, what is known as, a ‘matching run’ when the computer programme looks at all the people who are registered and works out who would match whom (perhaps the ultimate on-line match!).

Pool Exchange SystemThe pool exchange system: Mrs A cannot give her kidney to her daughter Miss A because she is the wrong blood group, and Mr B cannot give his kidney to his wife Mrs B because she has antibodies to his tissue type, but Mrs A’s kidney is a good match for Mrs B, and Mr B’s kidney is suitable for Miss A

It is important to note that

  • the person giving the kidney, as well as the person getting, stays in Belfast and the kidneys are transported rather than the patients
  • the donor will not be giving a kidney unless there is a kidney coming for their friend / relative on the same day
  • all the donors go to theatre at the same time, so there is no opportunity for one donor to change their mind

The advantage of this scheme is that the patients will receive a good ‘straightforward’ live donor kidney without any antibody problems. The disadvantage is that there is no guarantee of getting a match. In NI just over 40% of people who have been entered have had a transplant from the pool programme. People needing a kidney but who already have a lot of antibodies to other people’s tissue types (click here for further details) or who are blood group O have a much smaller chance of getting a successful match. But although the chances for some people (and we will tell you if this is the case) may be low, they are not zero so we usually recommend the pool programme at least for two or three ‘runs’.

If a match does come up, then the co-ordinators will be in touch to let you know. We will then get all the details about the donor in the other centre and the Belfast transplant team will review this information before accepting this kidney. At the same time the co-ordinators will arrange for blood samples to be collected and exchanged with the other centres to be sure that all is straightforward (the donor cells and recipients blood are mixed together and carefully checked to make sure there is no reaction). If all this is satisfactory the next step is to arrange a suitable date for theatre. This can be easier said than done, particularly when potentially three different centres are involved with six patients, surgeons, anaesthetists etc.! We aim to have the transplants completed within two months of the ‘run’ results but often this can take up to three months and very occasionally longer.

Obviously, given that there are so many other patients involved, there is a higher chance that the transplant will be postponed, even very close to the operation (everyone has to be well right up to the morning of the transplants). Clearly a very late cancellation is extremely disappointing for everyone when it happens, but usually it is possible to reschedule and go ahead after a short delay.

If a donor and recipient have not been successful in getting matched in the live donor pool after three or four runs then we will see if there are any other options for transplantation. This will be discussed thoroughly with potential donors and patients by the consultant, and any decision in regards to a higher risk type of transplant will be a joint decision.

Incompatible transplantation

Blood group / ABO incompatible

The problem with the donor being the ‘wrong’ blood group is that the person needing the transplant has antibodies in their blood stream to blood group A or blood group B proteins. If the kidney was transplanted the antibodies would recognise the A or B proteins in the kidney, attach to them and start to destroy the kidney. The table details what combination of donor and recipient blood groups are possible (compatible) and which are not.

  Recipient blood group
Donor blood group O yes yes yes yes
A no yes no yes
B no no yes yes
AB no no no yes

Some people however naturally have very high levels of blood group antibodies and some have low levels. Transplantation can be successful when the levels are very low naturally. In others with intermediate levels of antibody it can be possible to remove some of the antibodies with treatment so the levels become low enough that the transplant can go ahead.

The treatment is two-fold:

  1. Injection to prevent new antibody formation: This is given through the vein (it takes a few hours) about 3-4 weeks before the planned date for transplant as it takes this length of time to be effective. Most people tolerate the ‘drip’ very well. Occasionally people develop an itch or rash at the time, but this settles with paracetamol, anti-histamine, and slowing the rate of infusion.
  2. Removal of antibodies which are already present: This is performed in a manner similar to haemodialysis, where blood from the patient comes via tubing through a machine and is then returned to the patient. However instead of cleaning the blood of the waste products such as creatinine, potassium etc. as in dialysis, this machine cleans the blood of antibodies. It is known as plasma exchange or plasmapheresis. If the patient is not already on haemodialysis then they will require a plastic tube to be put into one of the neck veins (central line) to allow this to happen. (Usually this is a straightforward procedure performed by one of the kidney doctors using local anaesthetic). Each treatment takes approximately a couple of hours, but a little longer in larger individuals.

The number of treatments that will be required will be estimated for each individual based on the initial antibody levels. These are also checked before and after each treatment to gauge how successful it is, and the treatment plan will be altered accordingly. Typically the person is admitted to hospital a few days in advance of the transplant date. In some individuals the antibodies are ‘cleared’ very readily and they need less treatment than anticipated, others require an extra session or two. If the medical team are not completely satisfied that the antibody levels are sufficiently low then the transplant will be postponed rather than taking unnecessary risk.

What are the risks and outcomes for ABO incompatible transplants?

In Japan (where for cultural reasons deceased donor transplantation is extremely rare) ABO incompatible transplantation was started in the 1980s. They have very good long-term outcomes. In the UK and other Western countries a real interest in this type of transplant started in the early 2000s. Clearly this is a more complex transplant than a compatible one and the additional risks relate to:

  • Infection: the treatment to remove antibodies and stop their production is not selective i.e. it affects ‘good’ as well as ‘bad’ (the blood group) antibodies. People who have this treatment are therefore more prone to infection, and becoming ill from infection. Overall however this seems to very seldom be a significant problem.
  • Rejection: in most people the antibodies do not return, and when they do return they do not cause rejection. However, very occasionally the antibodies come back with a vengeance and really attack the new kidney. In this situation it can be impossible to be able to reverse this process and the kidney has to be removed.

Overall the outcomes from ABO incompatible live donor transplants are comparable but not identical to compatible (straightforward) live donor transplants. In the UK, three years after the transplant:

  • 94% of ABO compatible live donor transplants are still working
  • 92% of ABO incompatible live donor transplants are still working

This is still a superior result to transplantation from a deceased donor, and clearly much better in terms of outcome than being on dialysis.

The first ABO incompatible transplant in NI took place in October 2013 (click here for link to Coleraine Times story) and on average one takes place every 6-8 weeks in Belfast. So far all are working very well.

Tissue type / HLA incompatible

The principles and management are the same for HLA incompatible as for ABO incompatible transplants. In HLA incompatible transplants however the antibodies are directed against the tissue type (barcode) of the kidney itself. Click here for a more detailed explanation [For patients: What does matching mean?]. Overall these transplants do less well, as these antibodies can be more difficult to remove, more often come back after the transplant, and are almost invariably troublesome when they do return. HLA incompatible transplantation therefore is never the first choice, and is actually impossible in some cases. It is considered when the risks of NOT going ahead, (i.e. remaining for a prolonged time on dialysis), exceed the risks of going ahead with this type of transplant.

If this option is being considered it will be discussed in detail with you. The first of this type of transplant was carried out in Belfast in July 2014.  Prior to this, patients from NI all went to Guy;s hospital in London where they hav done many of this type of tranpslant.  We continue to have close links with this team and still recommend transplantation in London from some dono-recipient pairs where the rists are particuarly high. Between 2011 and 2014, 10 patients from NI had an HLA incompatible transplant in London, and in 1 of the 10 there was aggressive rejection and the kidney unfortunately had to be removed after a few days. However, many have had a very successful outcome.