NK Cells & Your Immune System

Are you well equipped to fight cancer and other diseases?

The Immune System

Your immune system works much the same way an army would, protecting you from foreign invaders trying to kill or damage your cells or organs. Your natural defense system fights pathogens such as bacteria, viruses and cancer cells to keep you healthy. Sometimes, these pathogens are small (e.g. a virus) and only require a few fighting cells (or soldiers) to kill them. Other times, pathogens are big (such as a tumor) and an entire squadron of soldiers is needed to kill them. When you have a strong immune system, or personal army, you are more likely to be well protected against infections, cancer and other diseases.

Your Personal Army

Your personal army is made up of two types of soldiers: the soldiers of the innate immune system and those of the adaptive immune system. The soldiers in the innate system are your first line of defense and hold down the fort until the soldiers in the adaptive system are trained and ready to attack invaders. Natural Killer cells are part of the innate immune system and are closer to a specialized unit of commandos that scout for enemies and once found kill and alert the rest of the immune system’s soldiers. They are not as numerous as T Cells, but as you can see, play a vital role.

The Innate Immune System

The soldiers in the innate immune system are always on patrol, they guard the front line and recognize and kill dangerous foreign cells on sight (this is known as “immunosurveillance”).

  • Found throughout your body
  • No need for previous exposure to any pathogens
  • Not specific about their targets
  • React quickly to invaders

NK Cells are the only ones that seek and destroy unidentified abnormal cells such as tumors. Once NK Cells recognize a tumor, they alert other cells, such as T Cells, to help.

The Adaptive Immune System

The adaptive immune system is made up of soldiers that are trained to target very specific invaders. Unlike the front-line soldiers that can identify and kill all pathogens on sight, these soldiers are trained to attack only specific pathogens. They help your body to recollect attackers so that it is better prepared to fight them in the future.

  • Training and initial deployment takes time
  • Must learn to recognize their targets
  • Once trained, will never forget a target
  • React quickly ensuing exposure to invaders

NK cell

Responsible for innate immune system to attack the virus or infected cells and cancer cells

B cell

Play a central role in cell-mediated immunity

NK Cell

B Cell
T cell

Involved in cellular immunity and controls the immune function


Play a critical role in nonspecific defense (innate immunity) and also help initiate specific defense mechanisms

T Cell


Natural Killer (NK) Cells

Your innate immune system include natural killer (NK) cells, a type of white blood cell or “lymphocyte” that have the ability to destroy compromised host cells, such as tumor cells or virus-infected cells. In your army, they are closest to elite commandos that scout your body and alert the rest of your soldiers. They are the only cells that can find abnormal tumor cells at first sight. As good scouts, once they find the enemy, they call upon other soldiers like T cells to come and help and as commandoes they start attacking. These cells play a key role in your immune system, as they are the first line of defense against dangerous foreign cells. When a foreign cell appears, the NK cells immediately recognize it and, like commandos, they move through your body to confront the foreign cell. Upon arrival, two things happen:

  1. An NK cell attaches to the foreign cell, causing a chain reaction that directly kills the foreign cell. This is called cytotoxicity - “cyto” for cell and “toxicity” for killing. The NK cells work together to release a protein in the blood called cytokine (“cyto” for cell and “kine” for movement).

  2. The cytokines are messengers that call upon other cells in the immune system to help the NK cells kill the foreign cells (or help prevent tumour growth).

NK Cell Function

NK cell function, also called NK cell activity, indicates how well your body can defend itself against dangerous foreign cells. NK cell activity helps your doctor assess the strength of your immune system for fighting off infections or cancer cells. Measuring NK cell activity does not tell your doctor if you have a disease or an illness; it does, however, help him or her decide what other types of tests you may need to have done.

Lifestyle & NK Cell Function

A number of conditions and diseases may affect your NK cell activity. For example, people who are highly stressed or who are not sleeping or eating well may have lower NK cell activity. Based on your NK cell activity results, your doctor may also recommend some lifestyle changes (weight loss, exercise, diet changes, smoking cessation, etc.), which could help to improve your immune system and improve your ability to fight cancer and other diseases.


Be sure to speak to your doctor about NK cell activity and what
you can do to improve your immune system.