As the number of measles cases rises in the U.S, research reveals a new way the disease can leave patients vulnerable to future infections.
Published in Science Immunology, an examination of measles patient immune systems showed that the disease didn't just leave some children less capable of fighting off infections they had already encountered. It also diminished their ability to fight ones that they had never been exposed to.
Measles leads to the death of over 100,000 people a year. In addition to wracking bodies with fevers and rashes, the disease can destroy a component of our immune system, called B cells. These white blood cells meet new pathogens, learn how to fight them off, and then remember how to do it in case our bodies encounter the disease again. As the number of experienced, “memory” cells grows, our immune system continues making a range of B cells that have never been exposed to disease and can tackle new threats.
Researchers knew that measles eliminates B cells in the immune system that form its memory. But this new analysis showed that the disease can also reduce the diversity of new immune cells, potentially impacting how someone responds to infections they’ve never had before. Measles remodeled some patient immune systems to look more like those of an infant, says study co-author Colin Russell, a biologist at the University of Amsterdam. “The only situation we’re aware of that’s like that is when we use immuno-suppressant drugs for organ transplants,” he says.
Russell and his team found these immune system changes in a population of Dutch measles patients. The group avoids vaccines on religious grounds and works with researchers studying measles, Russell says. When researchers predicted an outbreak was about to hit the group, they took blood samples from 26 children, then re-sampled just after they got sick.
Examinations of the memory cells showed there were fewer circulating in the patients’ bodies after infection, and that they were less genetically-diverse — meaning some of their disease-fighting abilities had been eliminated. In two of the kids, there were fewer and less diverse unexposed cells, too, potentially leaving them with less of an ability to fight new infections. These changes didn’t appear in blood samples from people who had been vaccinated for measles.
It’s not clear why measles impacted the unexposed cells of those two patients, Russell says. And because only two of 26 patients showed these results, researchers need a much larger study on a diverse population for a sense of how prevalent it is, or if it even shows up in other groups of people.
The results reinforce the importance of vaccinating children against measles, Russell says. And if these are the consequences of measles in a high-income nation where death from the virus is rare, it’s even more important this research be conducted in places where the disease is commonplace, he says.