NK cell activity is vital for maintaining health in many systems of the body, but their activity can wane during times of stress and fatigue. Infections, medications like steroids or immunosuppressants and disordered sleep can all decrease NK cell activity in the short-term. Long-term decreases in NK cell activity are experienced as a result of chronic medical conditions such as cancer, autoimmunity and neurodegeneration.
NK cells actively remove infected and abnormal cells and they can reduce autoimmunity by influencing and/or removing autoreactive T cells. NK cells help maintain the health of the body and are important protectors of the central nervous system, including the brain.