'Two for the price of one' tactic improves outcomes after organ transplantation

A new study of more than a million transplant recipients has found that rejection rates are lower in patients who receive two organs at once than in those who receive a single organ.

The study, published in Annals of Surgery, found that the rejection rates for organs cotransplanted with a donor-specific liver, heart or kidney were significantly lower than those for organs transplanted alone.

It has been known for some time that transplanting a liver with another organ such as a kidney or a section of intestine reduces the likelihood of rejection of the primary organ, leading to the suggestion that liver allografts protect other organs from rejection. Combined liver and kidney transplantation is used in patients with hepatorenal syndrome - in which acute kidney failure occurs as a result of liver cirrhosis or fulminant liver failure - or in patients with end-stage renal disease who also have liver damage as a result hepatitis B or C virus infection. Simultaneous intestine and liver transplantation is used in patients with intestinal failure following the removal of a large section of intestine (e.g. because of a tumor) and end-stage liver disease, which may be due to receiving their meals intravenously following intestine removal (total parenteral nutrition).

The recent study by Rana et al. has revealed that heart and kidney allografts are also immunoprotective and are themselves protected when transplanted with another organ.

The authors searched the United Network for Organ Sharing database – which contains data about every transplant that has taken place in the US since 1986 – and identified all thoracic, kidney, intestine and liver transplant recipients over 18 years old.

In patients who simultaneously received heart and kidney transplants from a single deceased donor, the incidences of renal allograft rejection and cardiac allograft rejection at one year were lower than in patients who received either a heart or a kidney allograft alone. In addition, the rate of rejection-free survival at one year was higher in the combined organ recipients. Likewise, compared with patients who received a single organ, rejection of either organ and rejection-free survival were lower and higher, respectively, in individuals who received combined liver and kidney transplants.

On the other hand, cotransplantation of intestine or pancreas in patients undergoing kidney or liver transplantation did not lower the risk of rejection or improve rejection-free survival.

The authors suggest that combined simultaneous organ transplantation could be used more widely to reduce rejection rates and lower the need for immunosuppression in transplant recipients.
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Rana A et al. (2008) The Combined Organ Effect: Protection Against Rejection? Annals of Surgery 248 (5): 871-879 DOI: 10.1097/SLA.0b013e31817fc2b8

Weird medical stories vol 1

When searching eTOCs or browsing the web, I can't help but be drawn to slightly strange or bizarre medical cases. Not the 'Pregnant man gives birth to a baby girl' genre of stories, although I will confess to a morbid fascination, but also disgust, at 'Urgh look at this freak' tales.

Given that I'm generally looking at clinical websites or the websites of journals I instead tend to pick out intriguing sounding case studies or clinical trials that have unexpected outcomes. This week's weird medical story was brought to my attention by the British Medical Journal, which highlighted a case study that suggests that peanut allergy could be be transferred by lung transplantation.

The case, published in the Journal of Heart and Lung Transplantation, is of a middle-aged woman who developed peanut allergy following a lung transplant from a donor who had died of anaphylactic shock after eating a peanut-related food. Although the transplant recipient did not previously have any allergy to peanuts, following the transplant she experienced anaphylactic shock herself and had to steer well clear of nuts.

Interestingly, transfer of food allergies from donor to recipient has been seen in liver transplantation. The phenomenon is thought to be due to either the transfer of IgE antibodies bound to cells within the donor liver or to relate to post-transplant use of the immunosuppressant agent tacrolimus. An instance of allergy transfer following bone marrow transplant also suggests that transfer of IgE antibodies or immunosuppression might be to blame.

The report in the Journal of Heart and Lung transplantation is the first instance of allergy being transferred by lung transplantation, however. As the study authors say, "This case emphasizes the importance of considering donor allergy transfer when caring for all solid-organ transplant recipients." I wonder if similar cases will start to appear in kidney transplant recipients and so on. Certainly this case could mean that finding an organ donor match could become more complicated, as it seems that potential donors with allergies might need to be struck off the list.