Natural Killer (NK) cells, a vital component of the innate immune system, have become a focus in the study of neurodegenerative diseases such as Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis (ALS), and multiple sclerosis. These cells are recognized for their ability to identify and eliminate infected, stressed, or abnormal cells, and they also play a role in modulating inflammatory responses by interacting with other immune cells and releasing signaling molecules. Researchers are increasingly exploring how the immune system, particularly NK cells, might be linked to the complex processes of neurodegeneration, which often involve chronic inflammation and the build-up of abnormal proteins. While this area of study is generating interest, experts caution that the clinical evidence is still in its infancy and does not yet support NK cell therapy as a treatment for these conditions.
In 2025, a Phase I clinical trial investigated the safety of using expanded NK cells in patients with Alzheimer’s disease, enrolling 11 participants, 10 of whom were included in the final analysis. These participants received autologous, non-genetically modified expanded NK cells intravenously at three-week intervals. The main goal of the study was to assess treatment safety, while also tracking cognitive changes and cerebrospinal fluid biomarkers linked to neuroinflammation, neurodegeneration, amyloid, and tau. The study reported no adverse reactions directly related to the NK cell product and noted some initial changes in cognitive measurements and biomarkers, such as pTau181 and GFAP. Nevertheless, this small-scale study was not designed to determine if NK cell therapy can prevent or slow the progression of Alzheimer’s, indicating that more extensive trials are necessary to evaluate its potential clinical benefits.
Preclinical research has also sparked interest in the potential role of NK cells in Parkinson’s disease. A 2020 study published in the Proceedings of the National Academy of Sciences demonstrated that NK cells could interact with and help degrade alpha-synuclein aggregates in laboratory and animal models. The study also observed increased alpha-synuclein pathology and neuroinflammation in a mouse model when NK cells were depleted, suggesting a possible regulatory role for NK cells in Parkinson’s disease-related immune activity. However, these findings remain largely preclinical, and the ability of NK cells to impact disease biology does not yet imply that administering them as a therapy could treat Parkinson’s in humans.
Research has underscored the complexity of NK cells’ roles in neurological diseases. Different populations of NK cells can have distinct functions, and their effects may vary depending on the disease type, stage, and tissue environment. Thus, merely increasing the number of NK cells might not yield beneficial outcomes. Researchers are actively investigating which specific NK cell populations, activation states, doses, and treatment schedules might prove effective. Vital questions remain about the therapeutic potential of NK cell therapies for neurodegenerative diseases, including their impact on the central nervous system, duration of activity, patient suitability, and ability to alter long-term disease progression.
At present, evidence clearly establishes that NK cells are active in immune surveillance and regulation, with emerging research suggesting their interaction with neuroinflammation and abnormal protein aggregates, particularly alpha-synuclein. However, it is not yet proven whether NK cell therapy can prevent, slow, or cure neurodegenerative diseases in humans. As such, NK cell therapy remains an investigational area, with further clinical studies needed to determine its efficacy and long-term safety. Individuals considering such therapies are advised to consult healthcare professionals to evaluate the scientific evidence, safety information, and regulatory status of these potential treatments.
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