Researchers observed that the cells are able to escape from the macrophages without destroying them, preventing an immune response.
Yeast fungus cells that commonly attack HIV infected patients escape detection by the immune system by hiding inside the body’s macrophages, according to scientists from the University of Birmingham, U.K. Studying cells of the Cryptococcus yeast, which causes cryptococcal meningitis, the researchers found that they additionally use these white blood cells as vehicles to travel inside the body.
“The yeast cells then escape from inside the macrophages when they arrive at the right destination,” explains Hansong Ma of the University of Birmingham. “Importantly, they do this without killing the macrophage, which would trigger alarm bells.
“This new method of remaining inside the host cells means that the pathogen can spread more efficiently around our bodies and is protected from the natural defenses in our bloodstream that would normally kill the yeast or other invader,” notes Ma.
“Yeast cells avoid killing or damaging the macrophages. They leave by a method that we call vomocytosis.” The investigators used time-lapse microscope photography to identify this new escape mechanism.
They were able to observe the yeast cells escaping into the fluid surrounding cells or directly into other host cells through cell-to-cell transmission, continuing to avoid detection by using this extremely rapid vomocytosis.
“Worryingly, this enables the cryptococci to avoid antifungal drugs and other treatments as well as our normal immune system, and may allow the yeast to become latent, achieving a long-term infectious state, which could then be spread even further to other individuals without anyone realizing,” Ma points out.
This data was presented at the Society for General Microbiology’s Autumn meeting being held this week at Trinity College, Dublin.
