by Dr. Joseph Mercola – June 25, 2018
Natural killer (NK) cells, a specific type of white blood cell, are an important component of your innate immune system. Your immune system consists of two different branches — cell-mediated immunity (innate) and humoral immunity (adaptive). When you contract a viral disease, the pathogen enters your body and infects your cells.
The subsequent disease process involves your cell-mediated immune response, which activates your NK cells, along with chemicals that attract them to the site of infection, where the white blood cells basically chew up and spit out the infected cells. This process clears the virus and rejuvenates the gel-like water inside your cells.
During recovery, your humoral immune system kicks in and starts generating antibodies against the virus to help prevent the same kind of disease process and symptoms from occurring again, should you be exposed to the same virus later on. As long as your cell-mediated immune system is activated first and the humoral immune system is activated second, you will have long-lasting immunity against that pathogen.
On a side note, naturally acquired herd immunity in a population comes into play when a very high percentage of individuals have gone through this sequence of cell-mediated and humoral immune response. This sequence is not followed during vaccination, which is why vaccine-induced “herd immunity” is a misnomer.
NK Cells Protect Against Viral Disease and Tumors
“NK cells are effector lymphocytes of the innate immune system that control several types of tumors and microbial infections by limiting their spread and subsequent tissue damage … NK cells are also regulatory cells engaged in reciprocal interactions with dendritic cells, macrophages, T cells and endothelial cells. NK cells can thus limit or exacerbate immune responses.
Although NK cells might appear to be redundant in several conditions of immune challenge in humans, NK cell manipulation seems to hold promise in efforts to improve hematopoietic and solid organ transplantation, promote antitumor immunotherapy and control inflammatory and autoimmune disorders.”
NK cells are cytotoxic, meaning they’re capable of killing cells. Tiny granules in the cytoplasm contain granzymes — special proteins such as perforin and proteases. Perforin, hinting at the functional basis of its name, perforates the cell membrane of the cell targeted for elimination, allowing the proteins and other chemicals to enter, thereby inducing apoptosis (programmed cell death) that destroys the virus along with the infected cell.
In this manner, NK cells — which are not antigen-specific — contain the infection while your adaptive, humoral immune response generates T cells containing antigen-specific cytotoxins to clear the infection. Put another way, the NK cells keep viral replication in check while the adaptive arm of your immune system “learns” the properties of the virus and creates antibodies to match.
Research confirms that when you are deficient in NK cells, you’re far more susceptible to viral infections, and likely tumor formation as well.2 NK cells also help regulate your immune system by producing cytokines, signaling molecules that stimulate and regulate other immune system cells.
Since NK cells have the ability to differentiate between normal, healthy cells and abnormal cells, such as those infected by a virus or that have turned cancerous, scientists are looking for ways to enhance NK cell function as a way to improve the effectiveness of cancer treatments.3,4 The good news is there are many ways to boost the number and function of your NK cells, which I’ll review below.
With Enough NK Cells, You Become Impervious to Influenza
Researchers recently made a very interesting discovery: With enough NK cells in your system, you will not contract influenza.5,6 As reported by Live Science,7 a specific gene called KLRD1 “could serve as a proxy for a person’s levels of natural killer cells.” KLRD1 is a receptor gene found on the surface of NK cells, and the level of KLRD1 found in a person’s blood prior to exposure to the influenza virus was able to predict with 86 percent accuracy whether that individual would contract the flu.
According to senior study author Purvesh Khatri, associate professor of medicine and biomedical data science at Stanford University School of Medicine,8 KLRD1 is “the first biomarker that shows susceptibility to influenza, across multiple strains.” As reported by Eurekalert:9
“[O]n the whole, those whose immune cells consisted of 10 to 13 percent natural killers [NK cells] did not succumb to the flu, whereas those whose natural killer cells fell short of 10 percent wound up ill.
It’s a fine line, Khatri said, but the distinction between the groups is quite clear: Everyone who had 10 percent or more natural killer cells stood strong against the infection and showed no symptoms. Khatri said his findings could help health professionals understand who’s at the highest risk for flu infection.”
Ways to Boost Your NK Cells
While the researchers hope their findings may help develop more effective flu vaccines, you don’t need drug intervention to boost your NK cells and hence your protection against virtually all viruses and malignancies. NK cells tend to lose functionality as you age, leaving you more susceptible to disease, including viral infections such as influenza and cancer. The medical term for this degeneration is “immune senescence.” The good news is you can counteract this decline in a number of different ways, including the following:
Get regular exercise
In one study, moderate exercise improved NK cell function in cancer patients.10
Enzymatically modified rice bran (EMRB)
EMRB is produced by exposing rice bran fiber to enzymes isolated from the shiitake mushroom. In one 2013 study, a rice bran product called MGN-312 increased NK cell activity by as much as 84 percent in patients with multiple myeloma after three months of treatment.13 In an earlier study, old mice injected with EMRB had a fivefold increase in NK cell activity within two days.14
A relative of turmeric, known for its potent immune-boosting benefits, cardamom increases NK cell activity.15,16 A 2007 study17 found cardamom inhibited colon cancer by preventing cellular damage caused by the accumulation of toxins and various waste products in the colon.
This tasty spice also has strong antioxidant and antimicrobial activity, effectively inhibiting E. coli, Staphylococcus aureus and Pseudomonas aeruginosa, the latter of which is a common source of hospital-acquired infections.