How does my immune system work? 

If you have tuned in it is probably because you have Hashimoto’s thyroiditis. If you have Hashimoto’s it is because your immune system has gone wonky. In future episodes, I will cover why this happens in more detail but to understand autoimmunity you first need to understand your immune system in general. 

The main purpose of your immune system is to keep out bacteria, viruses, parasites, and fungi. Our body has the perfect environment for all of these things to flourish which is why we have an immune system. The body has barriers such as skin, mucous membranes, and even stomach acid to keep these bacteria, viruses, parasites, and more from fully entering the body. If the body doesn’t keep out these bugs because one or more of the first lines of defense are not working well then your immune system gets to work to keep them from wreaking havoc. 

When something enters and gets past the first lines of defense, the immune system has to distinguish between self and non-self. It asks the question, ARE YOU ME? and ARE YOU DANGEROUS?  When your immune system is healthy, it will be able to tell the difference between self and non-self, so it doesn’t attack your tissue and just sets out to destroy actual invaders.  Your cells are marked as self and should not be attacked. When the immune system encounters cells or other organisms such as viruses or bacteria that are marked as non-self or foreign, an attack will be launched. 

The chemical triggering that attack is called an antigen and the response is called an immune response. Antigens can be a microbe like a virus, it can even be just part of a microbe. Other human tissues or cells will have foreign markers as well which is why organ transplants have a risk of rejection. 

Let’s talk a little bit about how the immune system is structured.  All organs of the immune system are called lymphoid organs. They house white blood cells called lymphocytes. Tonsils, adenoids, lymph nodes, lymph vessels, the thymus gland, the spleen, Peyer’s patches, your appendix, and bone marrow. Bone marrow is where we make blood cells which include white blood cells.  The thymus gland is where T cells mature. Lymphocytes travel through the blood and through the lymphatic system which runs parallel with our veins and arteries so cells and fluids can be exchanged between the two and be on the look out for invaders.  The fluid running through your lymph system is clear and it sort of “cleanses” the tissues of the body. 

You may have felt a lymph node when it is swollen. These are clustered together along your lymph vessels but especially around the neck, armpits, stomach, and groin areas. Your immune cells hang out here waiting to catch an antigen. Antigens are a protein or chemical that the immune system responds to and it can be pretty much anything but is likely to be a bacteria, virus, worm, food, allergen, or mold.  Your response to an antigen will be or can be different than someone else’s response because we all have different immune cells that are specific for things like mold or bacteria. That is why mold really affects some people and not others. 

Invaders and immune cells go through lymph vessels, exit through the lymph nodes, and make their way to the bloodstream where they go throughout the body looking for antigens, go back through the lymphatic system, and do it all over again. They are like a 24-hour patrol center. 

In your spleen is where immune cells congregate and plan. They bring an antigen there and that’s where they deal with it or decide what to do with it. 

The immune system has the ability to recognize most of the foreign invaders we could possibly encounter and when one of these invaders is known to be in the body, the cells that recognized it multiply themselves to create an arsenal of attacking cells to get rid of the invader. Once it’s gone, they dissipate but leave a few cells around to watch for that invader to come back. Kind of like a watchman that will alert the need for supporting troops to come help. 

Lymphocytes, those white blood cells, can be split into two groups. B cells and T cells.  B cells are made in the bone marrow and they make antibodies like IgG, IgA, and IgE (immunoglobulins).  Antibodies attack antigens in the blood. This applies to autoimmunity and leaky gut. When the gut is leaking and your digestion isn’t working well, antigens from food end up in the bloodstream, your immune system attacks and you become sensitive to the food. Once the B cell has identified an invader, the T cells are called in to attack it. B cells make antibodies, but only one per cell. So a B cell discovers an antigen and it tells a plasma T cell about it. The plasma cell then makes antibodies and sends them to the bloodstream. Antigens and antibodies are like puzzle pieces- some fit exactly right and sometimes you think you have it right but it’s not quite a good fit. Either way, when they fit together, the antibody sends a signal that the antigen needs to be destroyed. 

T cells don’t go around looking for antigens just floating around in the blood but instead, they have receptors that find antigens on a cell’s surface. These special cells will either regulate and instruct an immune response or they will attack an infected cell. You may have heard of Th1 and Th2 dominance spoken about in autoimmune disease, especially hashimoto’s. That is referencing T helper cells. These cells are like the cruise director on the old tv show The Love Boat. They coordinate and communicate with other cells like telling a B cell to make an antibody, or they call in the eater cells called phagocytes or they call in the killer cells. 

Natural killer cells are a type of killer cell. They release little particles that release a chemical that kills the invading cell and can attack any kind of invader. Other killer-type cells only kill cells with a specific antigen on them. 

I mentioned phagocytes or eater cells before. These types of cells swallow and digest invaders. A monocyte is a type of phagocyte in the blood that turns into a macrophage or big eater when it makes its way into tissue. They are found in the lungs, kidneys, brain, and liver among other places. Macrophages are like scavengers that clean things up. 

You have likely heard of histamine. That is produced by a cell called a granulocyte. They release granules that are full of chemicals, histamine being one of them, that set out to kill microorganisms that cause inflammation and allergic reactions like last year when I ate a tomato for lunch and proceeded to immediately get flush in my face and on my arms and legs. It was august and I tend to have a bit of a fall allergy so that combined with the fresh garden tomato was all my body needed to have a histamine reaction. 

Other cells that have granules they release are called neutrophils, a type of phagocyte, as well as eosinophils, and basophils. Mast cells are similar to basophils but aren’t found in blood but in the lungs, skin, tongue, and in mucosal linings and they also cause allergy symptoms. 

If you have been following Covid research at all you may have heard of a cytokine storm. Cytokines are hormone or chemical messengers. They talk to each other using their chemical messages where they act on other cells to create an immune response. Interleukins, interferons, and growth factors are cytokines. Interleukin 2 will tell the immune system to make T cells and, they can boost the immune system. Cytokines are also involved in repairing damage from inflammation or fighting off an invader- a bodyguard of sorts. 

We have something called a compliment system that has proteins that work with antibodies kind of like an additional force for good. They play a role in our inflammatory responses like when we hurt ourselves. The warmth of an injury, as well as the swelling, pain, and redness, are partially from the complement system.  In an immune response, there is a cascade of reactions that result in an invading cell being sort of drilled into. 

Infections are the most common issue we have as far as disease is concerned and the bugs causing those infections to have to get past our skin, mucous membranes in the respiratory system, and our digestive system. The only way to get past the skin is through a break in the skin. If a microbe enters your nose, you will make more mucous, you may even sneeze or cough in an attempt to keep invaders out. I think about sneezing in allergy season- that is your body’s way of trying to keep those little buggers out of the body. My daughter said she must have sneezed 40 times last night in the middle of the night- she has pretty bad seasonal allergies. I also think about my husband’s smoker’s cough. I imagine that his lungs are so damaged from smoking for 40 years (he’s only 54) that anything entering his lungs may be why he coughs so regularly. 

Our stomach is supposed to be acidic. I have talked about this in episodes about digestion. You need stomach acid. It is a line of defense against microbes that we swallow with food. If something makes it past all these barriers and we know that they do because we have all been sick. Our mucosal surfaces, stomach lining, intestinal lining and even the genital area are all lined with mucosal membranes that have IgA antibodies in them. Under that layer are macrophages, B cells, and T cells just waiting to identify an invader. Then they have to get past the phagocytes, natural killer cells, and the complement system which are all set up to destroy an invading substance.  On a side note to that- all this hand sanitizer being passed around everywhere these days to avoid Covid virus exposure - what do you think that is doing to your skin microbiome?  Likely changing its makeup and causing an issue with that particular immune barrier. Maybe instead of killing off the good bugs in addition to viral bugs, we should be providing our skin with the proper bugs to keep that immune barrier strong and healthy so it can fight off the bugs. Just something to think about- critical thinking my friends. 

Bacteria live in between cells and get attacked pretty easily by antibodies. Viruses and parasites have to enter cells to survive. If a cell gets infected it has its own defense system in place to tell the immune system to kill it. There are some parasites that can live outside of a cell, if they live outside the cell it is likely because they are too big to enter the cell and so more of the immune system has to get involved. 

We have two types of immunity. Innate/non specific and specific/acquired/adaptive. 

You are born with your innate immune system and it becomes active around 3-4 weeks and you need it to live. All microbes that get into the body are monitored by this system like a surveillance team. This is where most of the immune cells are made: 

• macrophages: this cell is in every tissue of the body ready to respond to invaders at all times and are very useful in the skin, GI tract, nose, and lungs where they produce cytokines which can be toxic to some invaders but they also call in more macrophages, dendritic cells, white blood cells to help in defending against invaders.

• Neutrophils: a white blood cell and a granulocyte (releases granules that are toxic to the invader) that kills anything. It wraps itself around the invader/eats it and kills it. And they eat and eat until they die. Pus is a good example of a neutrophil that has died and is a barrier between infection and the rest of the body.

• Eosinophil: another white blood cell that eats and kills but also will present antigens to T cells and B cells, is involved in allergies.

• Basophils: Another white blood cell doing similar work as neutrophils and eosinophils and is involved in allergies but there isn’t a lot of information on this one.

• Mast cells: these hang out around blood vessels and nerves and these are what release histamine, heparin (anticoagulant), and cytokines that cause swelling and bring in more of the macrophages and neutrophils to eat things up.

This branch of the immune system is what creates inflammation and part of that inflammatory process is due to the complement system because it calls in inflammatory cells coating invaders so they get eaten. It is also quick to react which is why it isn’t super specific so every response will be very similar no matter the reason it was activated. It also doesn’t care if it is a foreign invader, a damaged cell that needs to be taken care of or a perfectly healthy cell like one near a cut on the skin for example. This non-specificity only becomes a problem when you are dealing with inflammation due to chronic stress, infections that stick around, hormonal issues, or consuming a lot of foods that create inflammation which then leads to further health problems. 

Your specific or adaptive immune system is developed over time. The flora of the gut help develop it and you won’t live well if this system doesn’t work, but you can live. It can take over when your innate immune system can’t handle the infection, injury or inflammation occurring. When innate needs help, it takes one of those eaten microbes/viruses and presents it on its surface to show a T helper cell that can recognize the antigen presented. The T helper cell then gets activated, multiplies, and further activates the specific/adaptive immune system. 

This branch is specific in what it attacks and it remembers these invaders so next time they come by they can respond faster and more aggressively. If you have had chickenpox this is why you only get them once. Your immune system remembered that virus and keeps it from reinfecting you. It differentiates between self and non-self very specifically when responding to pathogens but this branch is also what attacks our tissues in autoimmune disease. 

There are two categories of adaptive immunity. 

Humoral and Cellular Immunity. 

Humoral immunity uses B cells created in the bone marrow and sent out into blood and lymph. B cells are what produce antibodies or immunoglobulins to fight off very specific things. Your body produces millions of B cells each day and each of these cells has a specific antibody on it so as it is circulating through your blood and lymph it is looking for a match to the antibody it is specific for. Once it finds it, if it finds it, it attaches to it and releases a signal to activate cytokines (made by T helper cells- which we will learn about later). The B cells for that antigen will then multiply themselves so the rest of that antigen can be gathered up. While it is multiplying it is also making a different kind of B cell called a plasma B cell that makes more antibodies to increase the attack on the antigen/foreign invader and memory B cells so it can remember this antigen for the next time it tries to invade. The innate immune system helps out here with their macrophages or eater cells and the complement system to clear out the invader quickly. 

Cellular immunity involves the T cell white blood cells that are developed in the bone marrow but go to the thymus for training before being released into the blood and lymph. There are two classes of T cells: CD4 and CD8 and they work with the receptor on the T cell to find invaders recognizing even a fragment of a foreign invader that may have been partially broken down inside the cell already. 

There are two major types of T cells: Killer T cells and Helper T cells. 

Killer T cells are CD8 cells that attack infected cells in the body- they are looking for foreigners presented on the cell surface and can be activated by other cells like macrophages, B cells and T helper cells to kill an infected cell. These are the ones causing issues with organ transplants and killing cancer cells. 

Helper T cells you may be familiar with as Th1 and Th2 are a part of this group and you may have heard these mentioned in relation to being Th1 or Th2 dominant. These cells tell the killer cells what to kill but they also release cytokines (inflammatory chemicals). Each of the Th cells releases a different kind of cytokine to create a certain type of immune response. 

Th1 cells involve innate immune cells like macrophages and cytokines that tell T cells to turn into killer T cells. Having too many Th1 cytokines can create hypersensitivity to food. These are the most commonly made cytokines and are also effective at taking on bacteria, viruses, some parasites and cancer. Taking ashwagandha can increase Th1 and that is only good if your Th1 is low. Reishi mushrooms also increase Th1. In the case of an infection, increasing Th1 would be okay. Th1 is high in ulcerative colitis in addition to food sensitivity. Low Th1 is related to actual food allergy and colon cancer. 

Th2 cells activate B cells which multiply and create antibodies. These are made in response to worms and parasites and when these are overproduced in the gut they can lead to food allergy or anaphylaxis. High Th2 is implicated in Crohn’s disease. 

Another T helper cell called Th17 is very inflammatory and is activated when we encounter some bacteria, fungi, or parasites. This increases inflammation to help get rid of bugs and is involved in asthma. This one is implicated in autoimmune disease and can produce Th1 or Th2- it all depends on the person and what is going on with them. This is probably too much information for you but I just wanted to lay it out there. The more you know the better equipped you are. 

There is another T cell called a regulatory T cell or T reg cell which is also a CD4 T cell that helps regulate (hence the name) the specific/adaptive immune system by shutting down the immune response when appropriate. They play a role in regulating the immune system in a way that creates tolerance where it will not attack an antigen (in pregnancy- so your immune system doesn’t attack your baby) and in stopping T cells that are preparing to attack self (our tissue). It is said that T reg cells also play a role in autoimmunity. They work to keep other cells from becoming pathogenic. If Th1 is out of control, T reg cells are supposed to keep it under control. You can increase your T regulatory response which will even out Th1 or Th2 by eating well, meditation, yoga, singing with people (strange I know), and some supplementation which I am not going to tell you about because I don’t want you to just go supplementing with something because you think this is a problem for you. 

To summarize 

Your immune system, when working well or when it is healthy, plays the role of detector and defender. It is tightly regulated within the body systems. It is reparative and it is tolerant (won’t attack you or the foods you eat).  We will get to what happens when it attacks you in a future episode. 

What is an antibody? 

These are proteins and are actually immunoglobulins which are the Ig in IgA, IgG, etc. The job of an antibody is to notice when another protein is near and bind to the part of that protein and deactivate it and also will send a signal out to the rest of the immune system if it has attached to a foreign protein (one it doesn’t recognize as safe for you). This can cause the immune system to react and attack.  Antibodies are Y-shaped with each part of the Y having a specific job. The tips of the Y have an antigen-binding site meaning it binds to antigens. It is like a lock and key. The antibody won’t bind to the antigen if it doesn’t fit just right. 

Immunoglobulins have classes or types characterized by another type of protein attached to them and are named IgM, IgD, IgG, IgE and IgA. Each has a specific type of thing it looks for in the body. 

IgM antibodies: these signal a potential recent infection as they are the first thing to respond to an antigen in the body. They are secreted by the B cells which remember are there to identify the invader/antigen and tell the T cells to attack. We make IgM antibodies to everything. 

IgD antibodies: there is not a lot known about these but they work with new/immature B cells and can activate other immune cells like basophils and mast cells to produce cytokines (inflammation chemical messengers).

IgG antibodies: these are in the greatest numbers in the blood (3/4 of the antibodies circulating) creating most of our antibody type immune reactions and gives us a Th1 response. These respond to bacteria and viruses. 

IgE antibodies: these bind to allergens and cause a histamine release giving you the symptoms you feel from your allergies such as pollen, rag weed or hay fever. These also bind to parasites and worms which are more common IgE reactions in less westernized countries.  

IgA antibodies: in mucosal areas like the small intestine, respiratory tract, and basically anywhere there are secretions in the body. These respond to food and some infections. 

All of these can be found in the blood with IgA being found in all secretions. 

What do antibodies do? 

They can coat or surround a microbe or other substance so it can be eaten and disposed of. They can neutralize things like toxins which in the case of botox injections is the reason why you have to get more and more of an injection for it to work. They activate the compliment system which is a series of proteins that poke holes in bacteria. They activate other cells like mast cells to break up worms to be eaten by macrophages or eater cells. 

Your immune response will be the same whether it is food, bacteria or viruses or allergens that your body is responding to. The immune response to food is the only thing that has what is called immunological tolerance so you are not reacting to everything you put in your mouth. When you have tolerance to food that is an IgA reaction. When you have a hypersensitivity or food sensitivity that is an IgG reaction and allergy is an IgE reaction. You can react to something you are sensitive to with the same reaction as an allergic reaction, the difference is that one is an IgG reaction and one is an IgE reaction. I have been told that healing the gut can allow someone to reintroduce those IgG reactive foods again. 

Consuming foods that provoke an IgG reaction regularly will create chronic inflammation through the overproduction of reactive oxygen species and oxidative stress along with the inflammatory cascade in the gut and then into the body systemically depending on how bad it is. Chronic inflammation can also be caused by obesity, gum disease, injury, underlying infections, mood disorders (here it is a chicken or egg situation- which came first). 

Bottom line- there is a lot we don’t know about the immune system and how it acts/reacts etc. Now you have a very basic understanding of the immune system so you can be more proactive in your own health. When we know better we do better. 

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Thanks for listening.