What Are NK Immune Cells?
Understanding your body's natural defense system
Natural killer (NK) cells are a type of white blood cell and a critical component of the body's innate immune system. Unlike other immune cells, NK cells do not require prior exposure to a pathogen to respond — they act as a rapid first line of defense against abnormal cells, including those infected by viruses.
NK cell activity is measured both by count (how many NK cells are present) and by activity level (how effectively they are functioning). Research suggests that low NK cell activity may be associated with increased susceptibility to illness, chronic fatigue, and impaired recovery.
Factors that can affect NK cell function include chronic stress, poor sleep, aging, and lifestyle habits. Assessing NK cell count and activity through a clinical test can provide a deeper understanding of your current immune function status — beyond what standard blood tests typically reveal.
Disclaimer: This information is for educational purposes. NK cell testing should be interpreted by a qualified physician alongside your full medical history.

