Although tissue compatibility issues exist for all patients receiving transplanted organs, rejection risks are especially high for a patient who has the added barrier of an immune system that has been exposed to "non-self" human leukocyte antigens (HLAs). Exposure may occur through blood transfusions, earlier organ transplantation or even pregnancy, when the mother is exposed to antigens from the father expressed in the cells of the developing baby. The immune system is then "sensitized" to those antigens primed with antibodies to attack, even if the antigens arrive in the form of a potentially life-saving donated organ.
The degree of sensitization is measured in terms of "panel reactive antibody" or PRA levels. For a non-sensitized patient with end-stage renal disease, the wait time for a cadaveric transplantation averages four to five years. For sensitized patients, the odds of being transplanted drop. According to the article, "the higher the PRA, the more difficult it becomes to find an immunologically compatible match. Transplant rates are lower for sensitized patients and the waiting times for a compatible crossmatch are longer. Furthermore, while many of these patients may have living donors, transplantation cannot proceed ."
In 2000, fewer than 3 percent of all kidney transplants were performed in patients with PRAs higher than 80 percent at the time of transplant, despite the fact that these patients represent about 20 percent of those on the waiting list. In fact, transplant rates for these patients have gone down over the past deca
Contact: Sandra Van
Cedars-Sinai Medical Center