Finding the right balance

Doctors currently monitor immunosuppressive treatment mainly by measuring drug concentrations in the blood. But the same concentration can have a different effect from one child to another. A blood level shows how much medication is present, but not exactly how strongly a child’s immune system is being suppressed. Biomarkers could add information about that response.

Looking at how the body responds

In an educational review published in Pediatric Nephrology, researchers examined biomarkers that could show how the immune system and donor kidney respond to treatment. Some provide information about the level of immune suppression, while others may signal an increased risk of infection, rejection or injury to the transplanted kidney.

Combined with current drug monitoring, they could help doctors adjust treatment more closely to each child.

Four promising biomarkers

The review highlights four biomarkers that appear particularly promising and can provide insight into the level of immune suppression. This could hopefully help doctors better assess in the future, for each individual patient, whether the immune system is being suppressed too much, increasing the risk of infections, or too little, increasing the risk of rejection of the donor kidney.

Torque teno virus (TTV) load could indicate how strongly the immune system is suppressed. Virus-specific T cells may show whether a child still has enough immune capacity to control viruses such as CMV, EBV and BK polyomavirus.

Donor-specific antibodies can reveal immune activity directed against the donor kidney and may indicate an increased risk of rejection. Donor-derived cell-free DNA consists of small fragments of DNA from the transplanted kidney that can be detected in the blood. Increased levels may indicate injury to the donor kidney.

Each biomarker measures something different. Using several together may eventually provide a more complete picture of a child’s immune response.

What still needs to be tested

Whether these biomarkers can actually improve treatment in children still needs to be tested. Much of the available evidence comes from adult kidney transplantation, and prospective interventional studies in children are still needed.

Future clinical studies will need to answer practical questions. Can biomarkers help doctors safely reduce medication when a child is more immunosuppressed than necessary? Can they identify children who need more protection against rejection? And does using them lead to better outcomes for transplanted kidneys?

Towards one kidney for life

This research closely matches the goals of Kidnie’s Moonshot 3: Transplant Care. One of its priorities is to optimise immunosuppression by tailoring treatment to each child’s immune system. The aim is to reduce side effects while still protecting the donor kidney from rejection.

Children who receive a donor kidney may depend on immunosuppressive medication for decades. Better insight into their individual immune response could help doctors find the right level of treatment. The goal of Moonshot 3 is to make transplants safer and longer-lasting, giving every child the best possible chance of one kidney for life.

About the publication

The educational review “Biomarkers related to immunosuppression in pediatric kidney transplantation” was published online in Pediatric Nephrology on July 14, 2026. Harm den Boer is the first author and is funded by the Kidnie Research Consortium. Several of the co-authors are also involved in Kidnie’s research on transplant care.

This research directly supports Kidnie’s Moonshot 3 (Transplant Care): personalising transplant care to reduce side effects, prevent rejection and help donor kidneys last for life.

The review is the result of a collaboration between all three transplant centres in the Netherlands, together with paediatric nephrologists from other European countries.