Researchers found that gamma-delta T cells lose much of their tumour-fighting strength when a key receptor falls silent after the cells mature. The result held across mouse models and laboratory tests with human cells.
In genetically modified mice, researchers switched off a receptor after gamma-delta T cells had matured and settled in tissues. The cells stayed in place, but they soon lost traits needed to monitor damage and respond quickly.
An international study published in Nature shows that the receptor acts as more than a trigger for development. Its signals must continue inside tissues so these immune cells remain alert, keep their tissue-resident features and react to abnormal cells.
The research was co-led by the Francis Crick Institute in England and the Universidad Complutense de Madrid, with help from the Centro de Biología Molecular Severo Ochoa, or CBM-CSIC-UAM. It examined a specialised lymphocyte found especially often in places such as the skin and intestine.
Adrian Hayday of the Francis Crick Institute said that without continuing receptor signals, gamma-delta T cells are much less able to perform their rapid immune “service” inside tissues.
Gamma-delta T cells patrol tissues and can react fast when they meet infected, damaged or abnormal cells. Their surface receptor gathers information from the surrounding tissue. That signal helps the cells decide when to stay put, switch on and defend the area.
This makes them a useful example of why the usual line between innate and adaptive immunity does not always hold. The cells respond quickly, like part of the innate immune system, but their readiness depends on continuing signals from an adaptive gamma-delta receptor.
The mouse experiment was built to test mature cells, not just developing ones. Researchers used animals with an internal genetic switch that allowed them to remove the receptor after the cells had fully developed and moved into tissues.
The effect was quick. The cells remained present, yet they began to lose the traits that helped them stay in tissue, track damage and respond properly to injured cells. That setup separated the receptor's role in development from its role in maintaining an immune function that was already established.
The receptor does more than guide gamma-delta T cells as they form. Its ongoing signals help keep mature cells ready to patrol.
A 2026 review in Frontiers in Immunology describes several ways gamma-delta T cells can damage tumour cells, including the release of perforin and granzyme B and the use of FasL and TRAIL pathways. The review also stresses that activity varies by cell subset and by the tumour microenvironment, so receptor-dependent readiness is only one part of the therapeutic picture.
Researchers then tested human gamma-delta T cells grown in the laboratory. Removing the receptor caused similar changes, especially in processes tied to immune defense and the cells' internal work. According to CSIC, the effect was not limited to one gamma-delta T-cell population or one tissue.
The cancer tests gave the finding its clearest practical weight. In three mouse models of skin cancer and colon cancer, tumours appeared more often or grew larger when the cells lacked the receptor.
Human gamma-delta T cells without the receptor were also less able to slow melanoma and colorectal cancer cells in laboratory tests. The result points to a loss of function, not simply a change in the cells' visible features.
Miguel Muñoz-Ruiz of the CBM-CSIC-UAM said the cells need continuing information from their surroundings to keep their defensive capacity. In this model, rapid immune action does not stay switched on by itself. It depends on an active link with the tissue.
That link helps explain how gamma-delta T cells can show traits tied to adaptive immunity and still respond with the speed usually associated with innate defenses. The receptor connects those two sides by helping mature cells keep their readiness.
The result also raises a practical issue for cell-based immunotherapy. Transferring or expanding gamma-delta T cells may not be enough if the process strips away the receptor signals that support their work in tissue.
Cells could reach a tumour and remain detectable there, yet have less ability to sense damage or mount a fast response. Simply adding more cells may therefore fall short if their receptor function is not preserved.
The study is basic research, not a new cancer treatment. Its value lies in identifying a condition these immune cells need before they can keep monitoring tissue and hold back tumour growth.
The mouse experiments and laboratory tests with human cells support a mechanism and a therapeutic hypothesis. They do not show that the approach works in people.
Gamma-delta T cells remain a possible basis for cell therapy because they can directly damage tumour cells and respond quickly to changes around them. The 2026 review in Frontiers in Immunology lists perforin, granzyme B, FasL and TRAIL among the ways these cells can damage tumours, while stressing that activity differs by cell subset and tumour microenvironment.
The receptor is therefore a possible target for future efforts to strengthen or control gamma-delta T-cell responses. The current evidence supports one firm finding: mature cells need continuing receptor signals to stay prepared.
