Cytotoxicity refers to the ability of a cell to kill another cell. This function is crucial in the immune system and is carried out by several immune cells, including natural killer (NK) cells, which destroy infected and diseased cells.
A meta-analysis – a comprehensive review combining data from multiple studies – conducted by a research team, including two researchers involved in an ME Research UK-funded study, found that the most consistent immune-related finding in ME/CFS research is reduced NK cell cytotoxicity. This suggests that NK cells in individuals with ME/CFS have impaired killing ability, supporting the broader hypothesis of immune system dysfunction in the disease.
What did the study do?
Through a review process, 28 papers were selected for the final meta-analysis. The researchers compared NK cell cytotoxicity between individuals with ME/CFS and healthy controls.
Key Findings
The study revealed that NK cell cytotoxicity in ME/CFS was significantly reduced, approximately half of healthy controls, suggesting NK cell dysfunction. However, the researchers noted “There is no consensus in the literature for the range of normal NK cell cytotoxicity or thresholds for ‘significant’ loss of function.” Additionally, the study highlighted that sample conditions affect results. Freezing cells and shipping blood samples reduce cytotoxicity, which must be carefully considered when interpreting research.
Despite these challenges, they suggest that NK cell function could have potential as a biomarker for ME/CFS. Nevertheless, “Fresh specimens or new methods will be necessary for NK cell cytotoxicity to become a routine clinical laboratory test for diagnosis.”
Future Research Directions
In relation to NK cell cytotoxicity, the researchers suggest that future studies report “behavioral correlations and investigate interactions with dysfunction of metabolomics, mitochondria, and brain cell function using magnetic resonance imaging in order to gain a better understanding of integrated disease pathophysiology and symptom generation.”
