Researchers at the University of Virginia report that an enzyme known as caspase-8 acts as a vital safeguard when immune cells are invaded by the parasite Toxoplasma gondii.
The findings, published in Science Advances, show that the enzyme enables infected CD8+ T cells to self-destruct, preventing the parasite from using them as a host.
According to the study’s senior author, Tajie Harris, this mechanism appears to be essential for limiting infection in the brain.
Without this built-in cellular shutdown system, the parasite can multiply inside the very immune cells meant to eliminate it.
Also read: Doctors outline signs of magnesium deficiency in the face and eyes
Why the discovery matters
Toxoplasma gondii infects roughly one in three people worldwide.
Transmission can occur through contact with cats, contaminated vegetables, or undercooked meat, according to Science Daily.
Although most healthy individuals experience no symptoms, the parasite can persist in the brain for life.
For people with weakened immune systems, however, the infection can become severe and potentially life-threatening.
Also read: GLP-1 medication may help reduce the risk of uterine cancer
The ability of a pathogen to invade CD8+ T cells is unusual. These cells play a central role in identifying and destroying infected tissue.
When a parasite infiltrates such frontline defenders, it risks undermining the body’s broader immune response.
Understanding how the immune system counters this threat may have implications beyond toxoplasmosis, potentially informing research into other chronic infections that target immune cells.
Evidence from mouse experiments
To investigate the enzyme’s role, scientists removed caspase-8 from CD8+ T cells in mice.
Also read: Trump’s testosterone level highlighted by Kennedy Jr. as remarkable
The animals were still capable of mounting an immune response; however, parasites accumulated extensively in their brains.
Brain tissue analysis revealed that T cells lacking the enzyme were more frequently infected, allowing the parasite to spread unchecked.
The affected mice developed severe disease and did not survive.
The researchers conclude that caspase-8 functions as a critical protective mechanism, helping the brain contain a widespread and often silent infection.
Also read: How to choose the healthiest yogurt at the supermarket
Sources: Science Daily, and Science Advances.
Also read: Climate-friendly diet can reduce mortality by 23 percent, new study shows