Scientists in Australia have uncovered a surprising link between blood cancer and diseases in which the immune system attacks the body.
The finding may help explain why some people with leukemia also develop autoimmune conditions.
The research was led by Dr. Etienne Masle-Farquhar and scientists at the Garvan Institute of Medical Research. Their study was published in the journal Immunity.
The immune system normally protects us from viruses, bacteria, cancer cells, and other threats. One important part of this defense is a group of white blood cells known as killer T cells, which can identify and destroy cells that appear dangerous.
These cells usually operate under tight biological controls. They need to attack genuine threats without damaging the body’s own healthy tissues, and problems can develop when that balance is lost.
The researchers focused on STAT3, a protein that helps control how cells grow, survive, and respond to signals. Changes affecting STAT3 have previously been linked to leukemia and disorders of the immune system.
The new study suggests that some STAT3 changes can turn killer T cells into harmful cells that no longer follow the body’s normal controls. These altered cells can multiply too much and attack healthy tissue instead of limiting their attacks to genuine threats.
This could help explain a medical puzzle that doctors have observed for years. Some people with blood cancers also experience autoimmune diseases, including conditions in which immune cells damage joints, blood-forming tissues, or other parts of the body.
Leukemia develops when abnormal blood-forming cells grow uncontrollably. Autoimmune disease is different because the immune system mistakenly targets the person’s own cells, but the new findings suggest that some of the biological processes behind these conditions may overlap.
To investigate the connection, the team studied blood samples from children with rare inherited immune disorders. The scientists also used CRISPR/Cas9 gene editing in mice to study what happened when STAT3 was altered.
The experiments revealed how powerful a small population of abnormal immune cells can be. According to the researchers, when only about 1% to 2% of killer T cells became abnormal, they could still be enough to cause autoimmune disease.
This means a dangerous immune response may not require most of the body’s immune cells to malfunction. A relatively small group of rogue cells could potentially disrupt the wider immune system and cause serious damage.
The discovery may eventually help doctors identify patients who could benefit from more targeted treatment. Genetic testing could potentially reveal harmful changes in immune cells and provide clues about why a particular patient is developing both blood and immune problems.
One possible treatment direction involves medicines called JAK inhibitors. These drugs interfere with signals used by immune cells and are already used for several inflammatory and blood-related diseases, although whether a particular drug is suitable depends on the individual patient.
The researchers also identified cell communication pathways linked to stress responses. Studying these signals could reveal additional ways to control abnormal immune cells without unnecessarily weakening the rest of the immune system.
In the future, advanced blood tests might make it possible to detect small groups of rogue immune cells before they cause major illness. However, more research will be needed before such testing becomes part of routine medical care.
The findings offer a new way to understand the complicated relationship between cancer and immunity. By showing how changes involving STAT3 can push normally protective cells toward harmful behavior, the research could eventually lead to earlier diagnosis and more precise treatments for some blood cancers and autoimmune diseases.
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