Can CBD help boost the immune system?
- Research has demonstrated that cannabinoids, similar to cannabidiol, can interfere with the release of cytokine(1). Cytokines are proteins involved in acute and chronic inflammation(2).
- CBD may theoretically play an integral role in managing autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis (MS), HIV/AIDS, and Parkinson’s disease(3). Autoimmune diseases are characterized by an immune system overreacting to non-threatening internal events, leading it to attack healthy cells in the body(4).
- Data from a review published in Cannabis and Cannabinoid Research in 2020 overwhelmingly support the concept that CBD is immunosuppressive (suppresses immune response)(5).
- Cannabis is known to be immune-modulating, which means it can bring an over- or under-reacting immune system back into balance(6). However, the difference between CBD’s “immune-modulating” and “immune-boosting” characteristics is still not well-understood.
- More longitudinal studies are needed to fully comprehend the impact of CBD oil on the immune system. Before using CBD to boost immunity, consult with a doctor experienced in cannabis use.
Why Some People Are Turning to CBD to Strengthen Their Immune System
CBD has several indirect anti-inflammatory effects on the central nervous system, which amplify its therapeutic effects.
Research has demonstrated that cannabinoids, such as cannabidiol, can interfere with the production of cytokines(7).
Cytokines are the proteins released by immune cells when the body experiences stress or trauma. Cytokines are involved in acute and chronic inflammation(8).
Autoimmune diseases are characterized by an immune system overreacting to non-threatening internal events, leading it to attack healthy cells in the body. The consequent inflammation can cause redness, heat, pain and swelling(10).
Traditional medications used to remedy autoimmune conditions are immunosuppressive and synthetically created. Unfortunately, as these medicines shut down the hyperactive immune system, they also leave individuals more susceptible to infection and illness.
On the other hand, based on the studies mentioned above, CBD may be able to manage those autoimmune conditions by suppressing only specific parts of the immune system.
However, there is also evidence that CBD oil can do the opposite. CBD oil has been shown to bolster a weakened immune system so that it can adequately defend the body and prevent infection.
In studies examining CBD’s effect on cancer patients whose immune system is greatly diminished, results have suggested that individuals are better able to combat cancer when taking cannabidiol.
For example, in one study published in the British Journal of Clinical Pharmacology, researchers said that there had been some clinical trials that indicated CBD might be effective at reducing tumor growth in particular cancers(11).
In another study, researchers found that cannabinoids in high doses prompted the body to kill cancer cells through a process known as apoptosis(12).
In a healthy immune system, apoptosis is triggered when infectious cells are detected in the body. The study’s findings are significant, considering cancer cells are characterized by their natural ability to avoid apoptosis, allowing them to proliferate throughout the body.
Although the specifics of how cannabinoids elicit this reaction are still being investigated, knowing that CBD oil may be able to inhibit cancerous cells when the immune system cannot is encouraging.
Data from a review published in Cannabis and Cannabinoid Research in 2020 overwhelmingly support the concept that CBD is immunosuppressive(13).
CBD’s potential as an immune suppressor means it may have positive effects when the immune system becomes hyperactive or weakened.
The said review also indicates that the mechanisms involve direct suppression of activation of various immune cell types, induction of apoptosis, and promotion of regulatory cells. These actions, in turn, control other immune cell targets.
Cannabis is known to be immune-modulating, which means it can bring an over- or under-reacting immune system back into balance(14).
As demonstrated in the studies discussed above, CBD can treat autoimmune disorders or its symptoms by calming a hyperactive immune system or strengthening a compromised one.
However, more longitudinal studies are needed to fully comprehend the difference between CBD’s “immune-modulating” and “immune-boosting” characteristics.
How CBD Oil Works to Help Strengthen the Immune System
To understand how CBD works to help boost immunity, one must understand how the endocannabinoid system (ECS) works.
The therapeutic effects of cannabinoids, such as CBD, are realized by their interaction with the body’s ECS and its specialized cannabinoid receptors.
The ECS, integral to the body’s physiologies, is responsible for regulating a wide range of body functions, including pain sensation, immune response, anxiety, sleep, mood, appetite, metabolism, and memory.
For example, it is through the interaction with cannabinoid receptors that anandamide, an intestinal cannabinoid, functions. Anandamide regulates appetite and stress response(15).
CB1 and CB2 receptors are found in specific parts of the human body, and each type of receptors have particular roles in the ECS.
CB1 receptors are mostly located in the brain and central nervous system(16). These receptors play a role in motor regulation, memory processing, appetite, pain sensation, mood, and sleep(17).
The activation of CB1 receptors has also been related to neuroprotective responses. This activity suggests the cannabinoids with a higher affinity for CB1 receptors could help in the treatment and prevention of neurodegenerative conditions, such as Parkinson’s disease, Alzheimer’s disease, and multiple sclerosis.
Meanwhile, CB2 receptors are primarily situated on cells in the immune system and its associated structures. When the CB2 receptor is triggered, it stimulates a response that fights inflammation, reducing pain and minimizing damage to tissues.
This anti-inflammatory response has been found to be useful for treating inflammation-related conditions, such as chronic inflammatory demyelinating polyneuropathy (CIDP), Crohn’s disease, arthritis, and inflammatory bowel syndrome (IBS)(18).
CBD acts indirectly against cannabinoid agonists, which are substances that bind to a cannabinoid receptor and cause the same action as the substances that typically attach to the receptor.
CBD also interacts with several other receptors in the body, such as the 5-HT1A receptor, which is linked to serotonin, a neurotransmitter found to be a contributor to feelings of well-being. It is through this interaction that these cannabinoids promote healing and balance(19).
The Pros and Cons of CBD Oil for the Immune System
- Studies mentioned previously demonstrate CBD’s potential therapeutic benefits in treating autoimmune disorders or its symptoms by pacifying a hyperactive immune system and strengthening a compromised one.
- CBD has been well-received by several health agencies, like the World Health Organization (WHO), which states that CBD “is generally well-tolerated with a good safety profile.”(20). CBD oil may be safer than most over-the-counter and prescription drugs that may have many side effects.
- CBD is non-addictive, says Nora Volkow, director of the National Institute on Drug Abuse (NIDA) in a 2015 article. This characteristic makes CBD safe for daily intake(21).
- CBD oil may be purchased without a prescription in locations where they are legally available.
- Studies are too limited to determine whether or not CBD is an effective treatment for conditions other than the ones approved by the U.S. Food and Drug Administration (FDA).
- As with the use of any natural chemical compound, there are risks involved in using CBD. According to the Mayo Clinic, possible side effects of CBD include drowsiness, dry mouth, diarrhea, fatigue, and reduced appetite(22).
- CBD has been shown to interact with other drugs and alter how the body metabolizes certain medications, as a 2017 research revealed(23). Consult with a doctor experienced in cannabis use before starting a CBD regimen or combining it with current prescription medications.
- Dr. Doris Trauner, professor of neurosciences and pediatrics at the University of California San Diego School of Medicine and a physician at San Diego’s Rady Children’s Hospital, cautions that CBD products marketed online and in dispensaries are mostly unregulated(24).
The lack of regulation makes it difficult to determine whether the CBD gummies, tinctures, patches, balms, and gelcaps contain what the product label claims.
A 2107 review published in the Journal of the American Medical Association revealed labeling inaccuracies among CBD products. Some products had less CBD than stated, while others had more(25).
How CBD Oil Compares to Alternative Ways of Boosting the Immune System
Primary immune disorders, such as B cell (antibody) deficiencies, T cell deficiencies, and combination B and T cell deficiencies, are caused by genetic defects, and there is no way to prevent them(26).
However, there are some ways to prevent infections in individuals with a weakened immune system, including managing stress and getting enough sleep, says Mayo Clinic(27).
This recommendation seems to be supported by the American Psychological Association, who says stress weakens the responses of the immune system and that friends and relaxation strengthen health(28).
Meanwhile, CBD oil has been shown to possess anxiolytic (anti-anxiety) properties that could theoretically help relieve stress.
A 2011 study published in the Journal of Psychopharmacology researched CBD’s impact on people with a social anxiety disorder (SAD)(29). Results showed that those who were given an oral dose of CBD experienced overall reduced anxiety levels.
In another study, published in Permanente Journal in 2019, most of the subjects who used CBD reported reduced anxiety and improved sleep(30).
Meanwhile, using essential oils (EOs) is another effective way of boosting immunity, and some experts agree.
A 2019 study published in Molecules analyzed the currently available scientific data supporting the efficacy of certain herbal products and summarized the immune-supporting properties of EOs(31).
The EOs used in the studies included eucalyptus, bergamot, orange, lavender, marjoram, ginger, lemon, patchouli, and rose. The authors found that some essential oils, particularly eucalyptus and ginger, seemed to have immune function-enhancing properties in multiple studies.
Essential oils are highly-concentrated, natural extracts from the leaves, flowers, and stems of plants. Like EOs, CBD is extracted from hemp, a strain of the Cannabis sativa plant.
Full-spectrum CBD oil contains all phytonutrients from hemp, including trace amounts of THC, terpenes, flavonoids, and essential oils.
Terpenes are the compounds in cannabis that give it distinctive aromas and flavors, while flavonoids are responsible for the vivid colors in most plants.
The terpene beta-caryophyllene, found in certain strains of cannabis, is known to decrease inflammation through its ability to stimulate the CB2 receptor. Myrcene, another terpene, also has anti-inflammatory properties in the laboratory setting(32).
The combination of all the components in a full-spectrum CBD oil creates a synergy known as “entourage effect,” where all of the constituents working together are more efficient than their isolated elements(33).
How to Choose the Right CBD for Boosting the Immune System
Studies cited previously show that CBD is not the only cannabinoid found in cannabis that can help treat autoimmune disorders or its symptoms.
Hence, when choosing a CBD product, opt for one that contains the full spectrum of phytonutrients from hemp, including trace amounts of THC, terpenes, flavonoids, and essential oils.
Those with allergies to THC may use a broad-spectrum CBD oil, which is like full-spectrum CBD but without the THC that makes the user high.
However, regardless of the form of CBD product of choice, careful consideration must still be employed in selecting the best CBD oil to help relieve inflammation, pain, and anxiety, and help promote healthy, functioning immune systems.
The following factors are essential to ensure the safety and reliability of the CBD products purchased:
- Research on the exact legal stipulations applicable to CBD in the area where it would be bought and used.
- Purchase only high-quality CBD products from legitimate and reliable brands. The majority of companies that manufacture the best CBD oil products grow their hemp from their own farm, or they purchase from licensed hemp producers.
- Research product reviews before buying from an online store. When purchasing from a physical store or dispensary, check whether the store is authorized by the government to sell CBD.
- One important thing to look for in CBD products is certification codes. Several certification authorities approve certain products only after some thorough screening tests.
- Compare company claims about their products’ potency with that of the third-party lab reports. Look for a certificate of analysis for every product purchased.
- Consulting with a trusted medical professional experienced in CBD use is ideal before one purchases his or her first bottle of CBD.
CBD Dosage to Help with the Immune System
There are few studies done with cannabidiol only in human autoimmune diseases, and there is no specific dose recommended for a particular disorder linked to the immune system.
However, CBD as Epidolex for epilepsy in children is being used as high as 20 mg/kg, but CBD doses as high as 300 mg/kg have been evaluated and have not exhibited significant adverse effects(34).
Autoimmune disorders have long been known as potential causes of seizures(35).
How to Take CBD Oil to Boost Immunity
One of the great things about CBD oil is its versatility. Individuals can consume it in oil or tincture form either sublingually (by dropping it directly under the tongue) or adding it to food or drink to help boost the body’s immune functions.
CBD oil tinctures or drops may be a practical option for those who seek fast results and maximum dosage control. Sublingual application allows for results to be experienced within 30 to 60 minutes after its use, and the effects can be felt for 4 to 6 hours.
Meanwhile, a topical CBD cream or CBD patch is ideal when dealing with inflammation or pain in a specific area of the body. When applied on the skin, the CBD cream or patch can interact with local clusters of cannabinoid receptors, instead of the ECS as a whole.
Many CBD creams and patches are also infused with other elements, such as essential oils, that may supplement CBD’s anti-inflammatory properties.
CBD oil capsules and edibles, such as brownies, gummies, and lozenges, are a convenient and straightforward way to take CBD oil, especially for beginners.
Medical cannabis (also called medical marijuana) is defined as a herbal drug derived from the cannabis plant that is used as part of the treatment for a specific symptom or disease(36).
Cannabis sativa L. (Cannabaceae) is a type of cannabis that is one of the most recognized ancient plants. Sativa is Latin for “useful”, and it is a term that is commonly used in plant names.
CBD oil may be derived from either a hemp plant or marijuana plant, although most CBD oil products in the market are hemp-derived.
CBD is non-psychoactive, making it favorable to those who want to experience its health benefits without the ‘high’ induced by tetrahydrocannabinol (THC). In general, a level of about 1% THC is considered the threshold for cannabis to have an intoxicating effect(37).
CBD Immune System Effects and Mechanisms
The immune system has evolved to discriminate between the body’s self-proteins from those of pathogens (organisms that cause diseases) in order to build a healthy immune response when there are foreign organisms(38).
An appropriate immune response requires a balance between normal reactions against non-self proteins, but limited or no reactions against self-proteins.
If an innate response is insufficient, specific innate cells can activate the adaptive immune response, composed predominantly of T and B cells.
T cells (thymus cells) and B cells (bone marrow-derived cells) are the primary cellular components of the adaptive immune response. Humoral (antibody-mediated) immunity depends on the B cells, while cell immunity depends on the T cells(39).
T cells and B cells are types of white blood cells (also called leukocytes or WBC). The white blood cell may be used to look for conditions such as infection, inflammation, allergies, and leukemia(40).
A high white blood cell count is usually indicative of an infection or immune system disorder(41).
T cells can then provide signals that recruit and activate other immune cells, or directly destroy or induce apoptosis (cell death) of infected cells. T-cells play a significant role in detecting and eliminating cancer cells in cancer patients(42).
Communication between the various cell types, as well as the natural and adaptive immune responses, is done through proteins called cytokines or chemokines.
Inflammation is the process usually linked to the natural immune response since pathogen destruction can also cause tissue damage. Many cell types produce cytokines in response to inflammation.
One important mechanism by which CBD acts to control immune responses is by generating regulatory T cells (Tregs)(43).
Regulatory T cells act to suppress the immune response, maintaining homeostasis and self-tolerance. It has been shown that Tregs are able to inhibit T cell and cytokine production and play a key role in preventing autoimmunity(44).
Autoimmunity is the system of immune responses of an organism against its own healthy cells and tissues.
Autoimmune disorders manifest when the body’s immune system attacks and destroys healthy body tissue by mistake(45).
The immunosuppressive and neuroprotective mechanisms of CBD make it an ideal therapeutic candidate for multiple sclerosis (MS).
MS is a neurodegenerative autoimmune disease of the central nervous system (CNS) that affects approximately 2.5 million people in the world(46). Further research is necessary to understand the potential benefits of using CBD with MS.
The Importance of a Strong Immune System in this Time of COVID-19 Pandemic
At the time of this writing, the rapid spread of the virus that causes Coronavirus Disease 2019 (COVID-19) has sparked alarm worldwide, prompting the World Health Organization (WHO) to declare this outbreak a pandemic(47).
The elderly and older people with chronic medical conditions, especially cardiovascular disease, high blood pressure, diabetes, and lung disease are more likely to have severe disease or death from COVID-19 and should engage in strict social distancing without delay.
People with compromised immunity because of a condition or treatment that weakens their immune response are also vulnerable.
According to WHO, to date, there is no vaccine and no specific antiviral medicine to prevent or treat COVID-19. However, possible vaccines and some specific drug treatments are under investigation, and they are being tested through clinical trials.
The immune system is the body’s defense system. Thus, individuals must keep their immune system healthy.
When a harmful invader, such a cold or flu virus, or the coronavirus that causes COVID-19, gets into the body, the immune system mounts an attack. This attack, known as an immune response, involves various cells and unfolds over time.
Keep the Immune System Strong
The best way to keep the immune system strong and healthy is to follow general health guidelines.
The immune system functions better when protected from environmental assaults and bolstered by healthy-living strategies, such as:(48)
- Do not smoke.
- Eat a nutritious diet rich in vegetables, fruits, and whole grains.
- Supplement with a multivitamin to include all the nutrients in the diet.
- Exercise regularly.
- Maintain a healthy weight.
- Control stress level.
- Control blood pressure.
- Drink alcohol only in moderation.
- Get enough sleep.
- Take steps to avoid infection, like frequently washing hands and trying not to touch the face, since harmful germs can enter through the eyes, nose, and mouth.
“Your immune system is a complex network of cells, tissues, and organs that work together to defend against germs. Its job is to keep these foreign invaders out or find and destroy them,” says an article by the National Library of Medicine (NLM)(49).
While there are immune disorders that are non-preventable, there are ways to help the immune system function better by protecting it from environmental assaults and strengthening it by healthy-living strategies.
Studies have suggested that CBD may help boost immunity and help protect the immune system through its anti-anxiety and anti-inflammatory properties.
Cannabinoid therapies may help decrease inflammation, modulate the immune system, and help bring the system back into balance(50).
Still, before using CBD to bolster the immune system, consult with a doctor experienced with cannabis use for advice.
Nagarkatti P, Pandey R, Rieder SA, Hegde VL, Nagarkatti M. Cannabinoids as novel anti-inflammatory drugs. Future Med Chem. 2009;1(7):1333–1349. doi:10.4155/fmc.09.93.
Feghali CA, Wright TM. Cytokines in acute and chronic inflammation. Front Biosci. 1997 Jan 1;2:d12-26. DOI: 10.2741/a171.
Hammell DC, Zhang LP, Ma F, et al. Transdermal cannabidiol reduces inflammation and pain-related behaviours in a rat model of arthritis. Eur J Pain. 2016;20(6):936–948. doi:10.1002/ejp.818; Rudroff T, Sosnoff J. Cannabidiol to Improve Mobility in People with Multiple Sclerosis. Front Neurol. 2018;9:183. Published 2018 Mar 22. doi:10.3389/fneur.2018.00183; Hanson R. (2019, June 4). CBD: A Promising Aid for HIV Patients? Retrieved from https://hivatis.org/cbd-a-promising-aid-for-hiv-patients/; Peres FF, Lima AC, Hallak JEC, Crippa JA, Silva RH, Abílio VC. Cannabidiol as a Promising Strategy to Treat and Prevent Movement Disorders?. Front Pharmacol. 2018;9:482. Published 2018 May 11. doi:10.3389/fphar.2018.00482.
MedlinePlus. (2020, March 12). Autoimmune Diseases. Retrieved from https://medlineplus.gov/autoimmunediseases.html.
Nichols J and Kaplan B. Immune Responses Regulated by Cannabidiol. Cannabis and Cannabinoid ResearchVol. 5, No. 1. 27 Feb 2020. https://doi.org/10.1089/can.2018.0073.
Russo S. op. cit.
Nagarkatti P. op. cit.
Feghali CA, Wright TM. op. cit.
Hammell DC et al. op. cit.
MedlinePlus. op. cit.
Massi P, Solinas M, Cinquina V, Parolaro D. Cannabidiol as potential anticancer drug. Br J Clin Pharmacol. 2013;75(2):303–312. doi:10.1111/j.1365-2125.2012.04298.x.
Guzmán, M., Sánchez, C. & Galve-Roperh, I. Control of the cell survival/death decision by cannabinoids. J Mol Med 78, 613–625 (2001). https://doi.org/10.1007/s001090000177.
Nichols J and Kaplan B. op. cit.
Russo S. op. cit.
Hao S et al. Low dose anandamide affects food intake, cognitive function, neurotransmitter and corticosterone levels in diet-restricted mice. Eur J Pharmacol. 2000 Mar 31;392(3):147-56. DOI: 10.1016/s0014-2999(00)00059-5.
Reggio PH. Endocannabinoid binding to the cannabinoid receptors: what is known and what remains unknown. Curr Med Chem. 2010;17(14):1468–1486. doi:10.2174/092986710790980005.
ECHO. (2017, April 18). Retrieved from https://echoconnection.org/look-endocannabinoid-systems-cb1-cb2-receptors/.
Turcotte C, Blanchet MR, Laviolette M, Flamand N. The CB2 receptor and its role as a regulator of inflammation. Cell Mol Life Sci. 2016;73(23):4449–4470. doi:10.1007/s00018-016-2300-4.
ECHO. (2017, March 29). Retrieved from https://echoconnection.org/differences-cbd-thc/.
WHO. Expert Committee on Drug Dependence. (2017, Nov 6-10). Cannabidiol (CBD). Retrieved from https://www.who.int/medicines/access/controlled-substances/5.2_CBD.pdf.
Nora Volkow. NIDA. Researching Marijuana for Therapeutic Purposes: The Potential Promise of Cannabidiol (CBD). National Institute on Drug Abuse website. https://www.drugabuse.gov/about-nida/noras-blog/2015/07/researching-marijuana-therapeutic-purposes-potential-promise-cannabidiol-cbd. July 20, 2015. Accessed January 31, 2020.
Bauer, B. (2018, Dec 20). What are the benefits of CBD — and is it safe to use? Retrieved from https://www.mayoclinic.org/healthy-lifestyle/consumer-health/expert-answers/is-cbd-safe-and-effective/faq-20446700.
Iffland K, Grotenhermen F. An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies. Cannabis Cannabinoid Res. 2017;2(1):139–154. Published 2017 Jun 1.
Peachman, RB. (2019, Feb 26). Can CBD Help Your Child? Retrieved from https://www.consumerreports.org/cbd/can-cbd-help-your-child/.
Bonn-Miller MO, Loflin MJE, Thomas BF, Marcu JP, Hyke T, Vandrey R. Labeling Accuracy of Cannabidiol Extracts Sold Online. JAMA. 2017;318(17):1708–1709. doi:10.1001/jama.2017.11909.
Mayo Clinic. (2020, Jan 30). Primary immunodeficiency. Retrieved from https://www.mayoclinic.org/diseases-conditions/primary-immunodeficiency/symptoms-causes/syc-20376905.
American Psychological Association. (2006, Feb 23). Stress Weakens the Immune System. Retrieved from https://www.apa.org/research/action/immune.
Crippa, J. A. S., Derenusson, G. N., Ferrari, T. B., Wichert-Ana, L., Duran, F. L., Martin-Santos, R., … Hallak, J. E. C. (2011). Neural basis of anxiolytic effects of cannabidiol (CBD) in generalized social anxiety disorder: a preliminary report. Journal of Psychopharmacology, 25(1), 121–130. https://doi.org/10.1177/0269881110379283.
Shannon S, Lewis N, Lee H, Hughes S. Cannabidiol in Anxiety and Sleep: A Large Case Series. Perm J. 2019;23:18–041. doi:10.7812/TPP/18-041.
Peterfalvi A, Miko E, Nagy T, et al. Much More Than a Pleasant Scent: A Review on Essential Oils Supporting the Immune System. Molecules. 2019;24(24):4530. Published 2019 Dec 11. doi:10.3390/molecules24244530.
Russo S. Molecular Mimicry: The Role of Cannabis in Healing Autoimmune Disease. Retrieved from https://www.fundacion-canna.es/en/molecular-mimicry-role-cannabis-healing-autoimmune-disease.
Russo EB. The Case for the Entourage Effect and Conventional Breeding of Clinical Cannabis: No “Strain,” No Gain. Front Plant Sci. 2019;9:1969. Published 2019 Jan 9. doi:10.3389/fpls.2018.01969.
Leo A, Russo E, Elia M. Cannabidiol and epilepsy: rationale and therapeutic potential. Pharmacol Res. 2016;107:85–92.
Mayo Clinic. (2014, Sept 17). Neurology and Neurosurgery. Retrieved from https://www.mayoclinic.org/medical-professionals/neurology-neurosurgery/news/new-approach-to-autoimmune-epilepsy/mac-20430556.
Ware M. (2020, Jan 23). Medical cannabis.https://www.britannica.com/science/medical-cannabis.
E. Small and D. Marcus, “Hemp: A New Crop with New Uses for North America,” in Trends in New Crops and New Uses, ed. J. Janick and A. Whipkey (Alexandria, VA: American Society for Horticultural Science Press, 2002.
Qualls and Murray. Chapter ten – Tumor Macrophages: Protective and Pathogenic Roles in Cancer Development. Current Topics in Developmental Biology. Volume 94, 2011, Pages 309-328. https://doi.org/10.1016/B978-0-12-380916-2.00010-3.
Cano and Lopera. Chapter 5 Introduction to T and B lymphocytes. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK459471/.
National Cancer Institute. NCI Dictionary of Cancer Terms. Retrieved from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/white-blood-cell.
Mayo Clinic. (2018, Nov 30). High white blood cell count. Retrieved from https://www.mayoclinic.org/symptoms/high-white-blood-cell-count/basics/causes/sym-20050611.
Qualls and Murray. op. cit.
Nichols J and Kaplan B. op. cit.
Kondĕlková K et al. Regulatory T cells (TREG) and their roles in immune system with respect to immunopathological disorders. Acta Medica (Hradec Kralove). 2010;53(2):73-7. DOI: 10.14712/18059694.2016.63.
MedlinePlus. (2020, Mar 4). Autoimmune disorders. Retrieved from .https://medlineplus.gov/ency/article/000816.htm.
Nichols J and Kaplan B. op. cit.
Harvard Health. (2020, March 16). Coronavirus Resource Center. Retrieved from https://www.health.harvard.edu/diseases-and-conditions/coronavirus-resource-center.
MedlinePlus. (2020, March 12). Immune System and Disorders. Retrieved from https://medlineplus.gov/immunesystemanddisorders.html.
Russo S. op. cit.