martes, 30 de marzo de 2010

No More Dialysis: Immunologists Develop Method To Decrease Rejections Of Kidney Transplants

No More Dialysis
Immunologists Develop Method To Decrease Rejections Of Kidney Transplants
October 1, 2007 — A nephrologist has found that a specialized type of anti-rejection therapy using intravenous immunoglobulin can make kidney transplants possible for patients with high 'anti-donor' antibodies. 25 to 30 percent of patients on the kidney transplant list could benefit from this therapy. Tissue compatibility issues exist with any organ transplant, but the risk is greatly increased for those with high exposure to antigens received through blood transfusions, previous transplantation, or even pregnancy.

Seventy-thousand Americans are waiting for a kidney transplant. A third of them are parked on dialysis because their antibody levels are too high for a transplant. But that's no longer a barrier for some people.

"I used to just sit around and throw up," says former dialysis patient Soraya Kohanzadeh.

Dialysis is something Kohanzadeh would rather forget, but if telling her story saves lives, it's worth it.

Kohanzadeh -- like many kidney failure patients -- developed high levels of "anti-donor" antibodies through blood transfusions. Her highly sensitized immune system would likely reject any donated kidney.

"Essentially, she would have a very short, sick life on dialysis," says Joan Lando, Kohanzadeh's mother.

But Kohanzadeh is no longer here, thanks to intravenous immunoglobulin therapy or IVIG. Here's how it works: during dialysis, patients are given blood containing a mix of immunoglobulins, which "turn-off" the anti-donor antibodies' attack response without suppressing the patient's immune system.

"A significant other comes forward, donates an organ, and there's an incompatibility there. We can treat the patient and remove those antibodies. Then the transplant can be done," Stanley Jordan, M.D., director of nephrology at Cedars-Sinai Medical Center in Los Angeles.

More than a year after surgery, Lando's kidney keeps her daughter alive.

"It was sort of shocking to think I wasn't going to have to be sick forever," Kohanzadeh says.

Through their website, this mother-daughter team works to spread the word of a little known therapy that could save thousands in need of a kidney. IVIG is covered by Medicare and can be used in both living and cadaver-donor transplants. Nearly 30 percent of patients on the kidney transplant list might benefit from this therapy.

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BACKGROUND: About one-third of kidney patients are often told they cannot have a transplant even if they have a donor with an otherwise perfectly matched tissue and blood type. Their anti-donor antibody levels are so high that any transplanted organ would be rejected by their highly sensitized immune system. Now there is a specialized type of anti-rejection therapy using intravenous immunoglobin (IVIG), which injects antibodies from healthy people into the blood supply, to modulate the immune system without suppressing it. This makes kidney transplant possible for as much as 25-30% of this group of patients, who would otherwise not be eligible for a transplant because of their high antibody levels.

DEALING WITH REJECTION: Tissue compatibility is an issue for all patients receiving organ transplants, but rejection risks are much higher for those with high exposure to human leukocyte antigens (HLAs) that are not produced by their own bodies. Exposure may be the result of blood transfusions, previous transplantation, or even pregnancy if the mother is exposed to the father's antigens, which are then expressed in the cells of the developing fetus. The immune system is then 'sensitized' to those antigens -- primed with antibodies that attack any foreign tissue, even if the antigens arrive in the form of a life-saving donated organ.

ABOUT IVIG: IVIG modulates the immune system without suppressing it. In fact, the therapy actually boosts the immune system because the antibodies found in IVIG help fend off infections -- a common post-surgery complication. For the most highly sensitized patients, IVIG is combined with a new drug, Rituxan, which reduces treatment time from four months to one before transplantation. The therapy can be used in both living-donor and cadaver-donor transplants. In the late 1980s. Dr. Stanley C. Jordan pioneered the use of IVIG as a way to reduce organ rejection among highly sensitized patients. It is now a fully accepted, Medicare-approved therapy as of 2004, when it was found to be effective in a multi-center study partly funded by the National Institutes of Health.

WHAT IS DIALYSIS? Hemodialysis is a treatment for end stage renal disease (ESRD), or kidney failure, in which blood is removed from the body, filtered through an artificial kidney and then the cleaned blood is returned to the body. In the US, hemodialysis is the most common treatment for people who have kidney failure. However, dialysis is also a painful, expensive procedure, and while it cleans the blood well enough to maintain existence, it does little to improve a patient's overall quality of life. Also, data shows that if patients get a transplant before they get to the point of dialysis, they do better in the longer term.

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