Intro to Natural Killer (NK) Cells
Natural Killer (NK) cells are a type of toxic lymphocytes that are critical to the immune system.
NK cells are produced in the bone marrow, lymph nodes, spleen, tonsils, and thymus, where they then enter into the circulation.
They control several types of tumors and microbial infections by limiting their spread and future tissue damage that can occur.
The cells become active around 3 days after infection and respond to tumor formation in the body.
NK cells monitor tumors that may grow by directly triggering the death of tumor cells.
They have the ability to recognize stressed cells without having to have previous exposure to the pathogens, allowing for a fast immune reaction.
NK cells can develop long-lived and highly specific memories to a variety of targets .
Extreme genetic diversity is present in both mice and humans coding for NK cells .
What Function Does Natural Killer Cells Have?
Individuals lacking NK cells have regular viral infections and die prematurely .
Individuals deficient in NK cells are prone to early phases of herpesvirus infection  and NK cells help fight HIV.
Mice with less NK cell function are more prone to cancers .
Activation of NK Cells
Circulating NK cells remain in their resting phase. NK cells activated by cytokines lead to the invasion of these cells into tissues with pathogen-infected cells .
NK cells release a membrane-disrupting protein, perforin, which causes cell death of the target cell .
So perforin perforates the “skin” of the pathogen .
Conditions With Elevated Natural Killer Cells
Obesity promotes the expression of inflammatory genes in the abdominal fat.
It elevates the number and activity of NK cells in only the stomach fat.
When NK cells are removed, inflammation in abdominal fat is suppressed and insulin resistance is improved.
NK cells control insulin resistance by transmitting proteins that affect macrophages .
In Asthma, NK cells contribute to IgE mediated immune-responses and may exacerbate the condition .
In Type 1 diabetes, NK cells increase the destruction of the pancreas .
Higher NK cells form in women who have reoccurring miscarriages .
Th1 Dominance and NK Cells
I actually don’t do very well with the more potent stimulators of NK Cells. This could either be because I don’t do well with NK cell stimulants, or because NK Cell stimulators have other immune-boosting properties – or both.
Conditions That Have Low Natural Killer Cells
- Cancer (low activity)  – NK cells ‘eat’ cancer cells.
- Viral infections (low number and activity)  – NK cells fight off viruses.
- CFS (low activity) 
- Multiple Sclerosis (low activity) 
- Rheumatoid Arthritis (low number and activity) 
- Lupus (low number and activity) 
Impairment of Natural Killer cells is also associated with advanced aging .
Natural Ways to Increase Natural Killer Cells
These strategies lead to increased natural killer cells.
- Curcumin 
- Zinc 
- Selenium 
- Garlic 
- Astaxanthin 
- Melatonin 
- Astragalus 
- Amla/Gallic acid – Not for Th1 dominant .
- Spirulina 
- Eleuthero 
- Danshen/Salvia Miltiorrhiza – A-glucosidase inhibitor. Slows carb absorption. Great for heart health 
- Blueberry 
- Echinacea or Cichoric acid (from Echinacea) .
- Spleen 
- Thymus Peptides – for weakened immunity 
Natural Ways to Enhance Natural Killer Cell Function
These strategies lead to increased function or cytotoxicity of Natural Killer Cells.
Supplements (if overactive immune system)
These supplements are safe if you are Th1 dominant and have an overactive immune system, but you’d still like to stimulate NK Cells.
- Curcumin 
- Resveratrol 
- Andrographis 
- Ashwagandha 
- Magnesium 
- Cardamom 
- Probiotics: S. Boulardii , L. casei , L. bulgaricus 
- Vitamin B12 
- Garlic (allicin) 
Supplements (if underactive immune system)
- Thymus – immune deficiency 
- Astragalus 
- Beta Glucans 
- Goji Berries 
- Reishi – night time 
- Gynostemma 
- Amla/Gallic acid
- Ginseng 
- Lion’s Mane [53, 54]
- Echinacea, Cichoric acid (from Echinacea) 
- Chlorella Tablets 
- GOS (galactooligosaccharides) 
- Germanium 
- Cocoacalm – nice relaxer 
- CoQ10 – in older women, but not men 
- Vitamin E – in older women, but not men 
- Low dose naltrexone (LDN) (drug) 
- Arabinogalactan [60, 61]
- T3 
- Growth hormone 
- IGF-1 
- Prolactin 
- MSH 
- Th1 dominance: IL-12, IL-2 (CD56bright NK cells) 
NK Cell Inhibitors
- Lectins initiate excess polyamine production, which may be the result of an effort to repair the damage to intestinal microvilli caused by lectins . A high polyamine level may decrease NK cell populations .
- Lipoic Acid 
- CRH/ACTH/Cortisol  – from stress or other causes
- Indoleamine 2,3-Dioxygenase (IDO) – activated by cortisol and inflammation 
- Folic acid (synthetic form) 
- Somatostatin (Growth Hormone-Inhibiting Hormone) 
NK Cell Cytotoxicity Inhibitors
Want More Targeted Ways to Combat Inflammation?
If you’re interested in natural and more targeted ways of lowering your inflammation, we at SelfHacked recommend checking out this inflammation wellness report. It gives genetic-based diet, lifestyle and supplement tips that can help reduce inflammation levels. The recommendations are personalized based on your genes.
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