Kidney or renal transplantation is the transplant of a kidney into a patient with end-stage renal disease. Kidney transplantation is typically classified as deceased-donor (also known as cadaveric) or living-donor transplantation depending on the source of the donor organ. Living-donor renal transplants are further characterized as genetically related (living-related) or non-related (living-unrelated) transplants, depending on whether a biological relationship exists between the donor and recipient.

Renal transplantation has become the treatment of choice for most patients with end-stage renal disease (ESRD). Kidney transplants are one of the most common transplant operations. Only one donated kidney is needed to replace two failed kidneys, making living-donor kidney transplantation an option. If a blood group compatible living donor isn't available for a kidney transplant, an ABO incompatible transplant can be performed. If no donor is available in the family, then the patient may get on to the waiting list to receive a kidney from a deceased donor. The wait could be about four years.

Related donors are preferred because the excellent genetic matching confers a low rejection risk and thus a longer life for the transplant kidney. This added to a huge shortage of cadaver donors makes those patients who have related donor fortunate indeed. Most patients on the cadaver list die waiting for a kidney. Related donors (father, mother, siblings, spouse, cousins, in-laws) usually step forward to donate.

However, even if they were deemed medically fit to donate, they were rejected if their blood groups weren’t matching. For e.g. blood groups A and O can donate to A; B and O can donate to B; anyone (A, B, AB and O) can donate to AB; and only O can donate to O.

Any transplants done against these rules would cause immediate rejection of the kidney. Due to this blood group divide, up to 40% of donors were deemed unsuitable earlier. Non-matching blood groups are called ABO incompatible. ABO-Incompatibility was an absolute contraindication to transplantation.

Now, due to medical advances and newer technologies, transplanting across any blood group is a routine affair.ABO incompatible transplantation involves two processes; removal of existing antibodies and preventing rebound formation of antibodies. The methods of removing existing antibodies are plasmapheresis, double filtration plasmapheresis (DFPP) or Immunoadsorption. An adult human may have a total blood volume of about 5 liters of which 2 liters are red blood cells, white blood cells and platelets. The remainder 3 liters are plasma which contains all protein, antibodies and clotting factors. Plasmapheresis removes these 3 liters which is replaced by plasma or albumin.

ABO incompatible transplantation differs from a compatible transplant only in the procedures performed prior to the surgery. After transplantation the risk of rejection, risk of infection and the longevity of the kidney are the same in both the kinds of transplants.

Across the world ABO incompatible transplantations are being done regularly in Sweden, Germany, USA and Japan. About 3000 transplants have been done in history so far. The first cadaveric kidney transplantation was performed in USA in 1950. ABO-incompatible transplantation was already performed as early as in the 1970s, but due to hyperacute rejection, the results were discouraging. But, due to a severe shortage of available deceased donor organs, most ABO-incompatible kidney transplantations have taken place in Japan. Published data demonstrate an excellent long-term outcome of ABO-incompatible living donor kidney patients in Japan. Similar successful short-term results have been shown for protocols developed in Europe and the United States.

An ABO incompatible transplant costs only about 15% more than that of a related transplant and almost similar to a cadaveric transplant. The higher cost is due to the cost of the extra medications and the Immunoadsorption device or plasmapheresis. For a patient who has no blood group matched donors, the costs of prolonged dialysis and the high risk of death while waiting for a cadaver transplant, more than justify the small extra cost of an ABO-incompatible transplant.