Plain language summaries of research

This is a plain language summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Why do transplant patients take immunosuppressive medication?

A kidney transplant is a surgical procedure where a healthy kidney from a donor is placed into someone whose own kidneys no longer work properly. For many people with kidney failure, this offers a much better quality of life than dialysis. 

However, the immune system naturally sees the transplanted kidney as something foreign and tries to attack it. This is called rejection. To prevent this, transplant recipients need to take medicines that weaken parts of the immune system. These are called immunosuppressive or anti-rejection medicines.

 

What are the challenges with long-term immunosuppression?

Anti-rejection medicines are essential, but they can also cause problems over time. These include infections, certain cancers, heart disease, diabetes, and even damage to the transplanted kidney itself.

Because of these risks, researchers are exploring ways to protect the transplanted organ while reducing the amount of immunosuppressive medication patients need.

 

What are regulatory T cells and why are they important?

Regulatory T cells, often called Tregs, are a type of immune cell that helps to keep the immune system under control. Instead of attacking, they act as a brake, preventing excessive immune reactions and helping the body to tolerate its own tissues.

These cells naturally exist in everyone. Scientists have learned how to collect regulatory T cells from a patient's own blood, grow larger numbers of them in a laboratory, and give them back to the patient as a form of treatment.

The idea is that these cells might help the immune system accept the transplanted kidney more calmly, potentially reducing the need for high levels of anti-rejection medication.

 

How was this treatment studied?

This research was part of a larger international project called the ONE Study, which tested different types of cell-based therapies in kidney transplant patients.

In Oxford, ten patients receiving kidney transplants from living donors took part. Before their transplant, a blood sample was taken from each patient to grow large numbers of regulatory T cells in the laboratory. Five days after the transplant, these cells were infused back into the patients.

At the time of transplantation, patients receiving the regulatory T cell therapy did not receive the usual induction treatment that strongly suppresses the immune system at the start of a transplant. They then continued on standard anti-rejection medicines used after transplantation.

Around nine months after the transplant, patients had a planned kidney biopsy, where a very small tissue sample was examined under a microscope. If the biopsy showed no signs of rejection, patients were offered the option of carefully reducing their anti-rejection medication under close medical supervision. 

The researchers then followed all patients for seven years to monitor kidney function and look out for any problems. They also had a control group of ten patients who received standard treatment without the cell therapy.

 

What were the findings after seven years?

After seven years, all ten patients who received the regulatory T cell therapy were alive and still had functioning kidney transplants. In the control group, nine out of ten patients were alive and eight out of ten still had functioning transplants.

None of the patients who received the regulatory T cell therapy experienced rejection of their transplanted kidney. Kidney function remained stable in these patients, while those receiving standard treatment showed a decline in kidney function after one to two years following their transplant.

In the report, three out of ten patients who received the cell therapy were able to reduce their anti-rejection medication without problems. The remaining patients continued standard medication alongside the cell therapy and also did well. Since the report, several patients have also successfully reduced their anti-rejection therapy. 

When kidney tissue samples were examined, the researchers found immune cells inside the transplanted kidneys that appeared different from those typically seen during rejection. These cells were linked with immune regulation rather than inflammation. 

Because this was a small early-phase study, it cannot prove that the cell therapy improves long-term survival, but it does show that the approach is safe and associated with encouraging long-term outcomes.

 

What does this mean for transplant patients?

These findings suggest that regulatory T cell therapy may create a protective immune environment within the transplanted kidney, helping to prevent the body from rejecting it.

Some patients were able to successfully reduce their immunosuppressive medication and their kidneys continued to function well. This suggests that this approach could, in the future, help more transplant patients reduce their reliance on long-term immunosuppression. Doing so could help to reduce the serious risks associated with these medications.

 

It is important to note that this was a small study of only ten patients, and not all patients decided to reduce their anti-rejection medication. Larger clinical trials are needed to understand how effective the therapy is.

 

What happens next?

The research team is conducting a larger study with more kidney transplant patients to see how effective and safe this treatment is when it is used more widely. 

They are also continuing to study the immune cells found in kidney tissue to understand how tolerance develops after transplantation.

Read the full article

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Funding

This study was funded by the 7th EU Framework Programme and the National Institute for Health Research (NIHR).

The original article

This is a summary of: McCallion et al. (2025). Regulatory T cell therapy is associated with distinct immune regulatory lymphocytic infiltrates in kidney transplants. Med, 6(5), 100561. Available at: https://doi.org/10.1016/j.medj.2024.11.014 

This summary has been approved by a member of the research team.