Antibody-mediated rejection is a form of kidney transplant rejection in which the immune system makes antibodies that attack the transplanted kidney, and it is one of the leading reasons transplanted kidneys stop working [1].
This page provides general information. It does not replace advice from a doctor or another qualified healthcare professional.
A transplanted kidney is a treatment rather than a cure, and it depends on daily medicines that stop the immune system attacking it [7].
Rejection happens when the immune system, the body’s defense against germs, recognizes the transplanted kidney as someone else’s and attacks it [6].
There are two main forms [2]. T cell mediated rejection, driven by white blood cells called T cells that inflame the tiny tubes carrying urine, is more common and usually treatable with steroids [6,13]. Antibody-mediated rejection, or AMR, is driven by antibodies, proteins the immune system makes to recognize things it treats as foreign [1]. These stick to the lining of the kidney’s smallest blood vessels and injure them, and AMR is harder to treat [3,6]. Papers write it as AMR or ABMR [3].
Active AMR means a biopsy shows current injury only. Chronic active AMR means current injury plus permanent scarring, and chronic rejection is the most common reason transplanted kidneys eventually fail [3,9].
Rejection of any type affects 10 to 15 in every 100 people in the first year after a kidney transplant [6]. AMR is the less common form, described as affecting fewer than 1 in 10 recipients. A review of 28 studies reported rates of 3 to 12 percent, with chronic AMR in 7.5 to 20.1 percent of people over 10 years [1,2]. Around 23,000 people in the United States are estimated to be living with some form of AMR, for scale against 27,332 transplants there in 2023 [8,15].
Read those figures with care. AMR can only be confirmed on a biopsy, so how often it is recorded depends on how often biopsies are done, which varies between countries. Silent AMR never enters the figures, and reliable global numbers are not available.
Everyone carries markers on the surface of their cells called human leukocyte antigens, or HLA. Finding a person’s HLA pattern is called tissue typing, and teams compare it with a donor’s to judge how well matched they are [5]. HLA patterns are inherited, which is why a relative is often a closer match, though AMR itself is not inherited and cannot be passed to children [7].
Antibodies aimed at a specific donor are called donor-specific antibodies, and they are the main cause of AMR [1]. Preformed antibodies were present before the transplant and often lie behind early AMR. De novo antibodies appear afterward, sometimes years later, and tend to cause the slower chronic form [2].
How people come to carry them surprises many. They can form after a previous transplant, after a blood transfusion, or as a result of pregnancy, and once formed they are very hard to remove [5,6]. None of those are things to regret, and rejection is not a sign anyone did anything wrong.
When blood levels of anti-rejection medicine fall, through missed doses or a planned reduction, the risk of forming donor-specific antibodies and developing AMR rises [2]. In one study following transplants to failure, every kidney lost to rejection showed antibody-mediated features, and nearly half of those recipients had been recorded as having trouble taking their medicines [12]. Taking tablets every day for decades is hard, and teams would rather hear that someone is struggling than find out later.
AMR often causes nothing at all. Many people feel completely well while it is happening, which is why routine blood tests and appointments do so much of the work [1,9]. Rejection usually begins before there is anything to feel, and a rising level of creatinine, a waste product measured in the blood, is often the first signal [1,7,11].
When symptoms do appear they can include [1,9,11,21]:
When to seek urgent help. Contact the transplant team the same day if the amount of urine passed drops noticeably, if swelling worsens over a day or two, if breathing becomes difficult, if there is new pain over the transplant, or if there is a fever of 101 degrees Fahrenheit, about 38.3 degrees Celsius, or higher [9,21].
A transplant center and a nephrologist, a kidney specialist, share the care. Diagnosis begins with routine tests: creatinine and other blood tests, a urine test for protein, and a blood test for donor-specific antibodies [1,7].
If those suggest a problem, the next step is a biopsy. A very small piece of the transplanted kidney is taken with a needle, usually under local anesthetic, and examined under a microscope. It carries a small risk of bleeding and is the only way to confirm AMR [1,6].
Biopsies are graded using the Banff classification, the international standard, most recently updated in 2022 [3,4]. Under Banff, AMR rests on three things together: injury to the small blood vessels, evidence that antibodies have been interacting with the vessel lining, and donor-specific antibodies in the blood [3]. The antibody evidence often comes from a stain called C4d, which is helpful rather than decisive, since AMR can occur without it [3,13].
Two newer tools, not yet routine everywhere: molecular diagnostics, which read gene activity in the biopsy sample, and donor-derived cell-free DNA, which measures fragments of donor DNA in the blood and may signal injury earlier [2,3]. Some centers biopsy at set times whether or not anything looks wrong, which is how silent AMR is often found [2].
This section has to be honest. No medicine is approved anywhere specifically for treating AMR [1,2]. Everything used today is used off label, meaning prescribed for a purpose it was not licensed for, and the evidence comes largely from expert opinion and small uncontrolled studies [2].
Current options include [1,2]:
Two medicines widely hoped for were properly tested and did not work. Rituximab showed no benefit for kidney function or transplant survival, and bortezomib no effect on antibody levels, biopsy findings or kidney function, so neither has evidence strong enough for routine use [2].
A 2023 European survey found more than half of people with chronic active AMR receive nothing beyond adjusted medicines, partly for want of trial data and partly because existing scarring may not be reversible [2]. If the kidney does fail, dialysis is needed again, and a person can be assessed for another transplant [1,21].
Follow-up runs for years, with blood tests tracking creatinine and medicine levels, and appointments that continue even when everything feels fine [6,9].
Anti-rejection medicines are usually two or three tablets a day, for as long as the transplant works, and should never be stopped or skipped however well a person feels [9]. If cost, side effects, forgetfulness or the weight of a daily routine gets in the way, that is a conversation to have with the team rather than a failing to hide [2]. The same medicines lower the body’s defenses, so infections need reporting early, skin and cancer checks are recommended, and blood pressure is worth checking at home weekly [11].
Being told the body may be rejecting a kidney someone waited years for is frightening. Many people live well after AMR, and peer groups and mental health professionals both help [1].
Clinical trials test whether a treatment works and is safe. AMR has no approved treatment, so research is unusually active [1,2]. The decision is personal, and it helps to take it in steps.
It is worth being clear on what a study involves:
Every trial has rules about who can take part, called eligibility criteria. Some describe who can join, others who cannot. For an AMR study they might include AMR confirmed on a biopsy graded by the Banff system, donor-specific antibodies in the blood, a transplant carried out more than six months ago, and a stable dose of anti-rejection medicine beforehand.
trialport’s medifit helps people consider information related to possible medical suitability. It does not diagnose a condition, confirm eligibility or replace formal screening by the study team.
Explore antibody-mediated rejection clinical trials through trialport
Medical suitability is only part of the picture. A study can look right on paper and still be hard in practice. Worth thinking through:
trialport’s readifit helps people reflect on their understanding, motivation, time, routines, support, emotions and practical arrangements.
Useful questions to put to a research team:
Taking part is voluntary. A person can ask questions, speak with people they trust and choose not to participate.
Search for clinical trials at app.trialport.com.
The main research areas, and what has already failed:
Study status checked: 3 August 2026. Research moves quickly, so this list will date. For current information, search at app.trialport.com.
In the United States, the American Kidney Fund has the clearest plain-language page on AMR itself [1]. The National Kidney Foundation covers life after a transplant, medicines and rejection [9,10], and the American Society of Transplantation publishes a patient toolkit for the transplant journey [11,24].
In the United Kingdom, NHS Blood and Transplant explains tissue typing, antibody testing and rejection in ordinary language [5,6], and Kidney Care UK provides advice, emotional support and financial grants [20].
In Australia, Transplant Australia supports recipients, families and donor families, including peer support [22], and Kidney Health Australia offers support across kidney disease [23].
Coverage elsewhere is thin, and no organization specifically for AMR was found in any country. Where no local group exists, the treating transplant unit is the best starting point.
Does antibody-mediated rejection mean I will lose my transplant?
Not necessarily. Rejection does not by itself mean the kidney will fail, and adjusting medicines is sometimes enough [21]. Finding it early gives treatment the best chance [1].
Why did nobody warn me? I feel fine.
AMR often causes no symptoms, and rejection usually begins before anything can be felt, which is why blood tests continue even when everything seems well [1,7].
Was this my fault?
Rarely in the way people fear. Antibodies commonly form because of a previous transplant, a blood transfusion or a pregnancy, none of which were mistakes [5,6]. Missed doses do raise the risk, and the useful step is telling the team so it can be solved [2,9].
Is there a cure?
No. No treatment is approved specifically for AMR anywhere, and current options are used off label with limited evidence [1,2]. Treatment aims to calm the immune attack and protect the kidney.
Can I have another transplant if this one fails?
Often yes, after returning to dialysis and being assessed again, though existing antibodies can make the wait longer [5,21].
Written by: trialport editorial team
Reviewed by: Keith Berelowitz, Founder and CEO, trialport
Reviewed on: 3 August 2026
Next review due: 3 August 2027
References last checked: 3 August 2026