Aged immune system fails against tuberculosis infection
Tuberculosis still kills more than a million people every year. Older adults are far more likely to die from it than younger people.
Researchers are now working to build a more detailed picture of what goes wrong. The research focuses on specific changes in the immune response of older animals during a tuberculosis infection, using aged mice as a model. This approach remains underused in infectious disease research.
One central finding is that older animals show a weakened response from T-cells, the white blood cells that identify and attack infected cells. At the same time, there is more generalised inflammatory activity that does not contribute effectively to clearing the bacteria. This combination, less targeted defence and more diffuse inflammation, leaves older organisms vulnerable to an infection that younger bodies can contain.
Studying infections in old animals
A structural problem in this field is that most infectious disease studies use young animals. Treatments that work in young subjects do not automatically translate to older ones. Tuberculosis vaccines, including the BCG vaccine, offer older adults substantially less protection. This has long been known, but the precise reasons have not been established.
This research aims to close that gap by mapping which components of the immune response fall short in older animals. That information is essential to design vaccines and treatments better suited to older immune systems.
Implications for vaccine and therapy development
Once researchers identify which immune cells or signalling molecules are most deficient in older animals, they can search more precisely for ways to strengthen them. This might involve new vaccine formulations designed specifically for ageing immune systems, or treatments that provide temporary support during an active infection. Tuberculosis is a useful model here because the bacterium triggers a sustained and complex immune response. What is learned in this context may also apply to other infectious diseases where age plays a significant role.
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