Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex, debilitating disease. People with ME/CFS experience at least six months of profound exhaustion and extremely poor stamina that doesn’t improve with rest. Other symptoms may include joint and muscle pain, sleep problems, tender lymph nodes, a sore throat, headaches, GI issues, and problems with thinking and cognition.
The cause of this disease is unknown. Sometimes it starts after a person has flu-like symptoms. Studies have suggested that infections, stress, or immune system changes may be involved.
One of the main characteristics of ME/CFS is that symptoms get worse within 12 to 24 hours following physical or mental exertion, which is known as post-exertional malaise. When you exert mental or physical energy, cells need to consume ATP, a small molecule that provides energy for cells to carry out their functions. Some studies have found that the ability to use ATP may be impaired in people with ME/CFS.
There are currently no diagnostic tests for ME/CFS. To test whether they could use ATP consumption to identify individuals with ME/CFS, a team led by Dr. Ron Davis at Stanford University developed a technique called a nanoelectronics assay that can measure the electrical responses of cells in real time. Support for development of the device was initially provided by NIH’s National Human Genome Research Institute (NHGRI). Results were published on April 29, 2019, in the Proceedings of the National Academy of Sciences.
The researchers looked at peripheral blood mononuclear cells (PBMCs), a type of immune cell that is easy to isolate from blood samples. They compared PBMCs from 20 people with ME/CFS and 20 healthy controls. They placed the cells in a high salt environment, which creates a type of stress that cells can usually fix using ATP.
Cells from healthy controls had a period of electrical change when exposed to high salt levels but soon returned to normal. Cells from all 20 people with ME/CFS, in contrast, showed significantly greater electrical changes. This suggests that the healthy cells were able to more effectively handle the stress of a high-salt environment.
Cells from more severely ill people showed the greatest changes, while those from healthy controls showed the lowest. These results suggest that the assay’s signal strength may reflect disease severity.
The team also optimized the assay for potential diagnostic use by comparing immune cells taken from blood plasma, whole blood, and serum. Plasma samples tested within five hours of collection yielded the most reliable results.
“We don’t know exactly why the cells and plasma are acting this way, or even what they’re doing,” Davis says. “But there is scientific evidence that this disease is not a fabrication of a patient’s mind. We clearly see a difference in the way healthy and chronic fatigue syndrome immune cells process stress.”
In addition to allowing an accurate diagnosis, this assay could be used to test how effective drugs are for treating the disease. However, more studies are needed to confirm these findings and ensure the assay is specific for ME/CFS before it could be used in the clinic.