A Brief Tour of Your Immune System

For the past 10 years, I’ve spent my free time and creative energy learning and teaching about neuroscience and the human nervous system. It’s why our office has evolved to integrate neuroplasticity in our clinical practice.

However, there was a time where I was a major in Microbiology/Molecular Biology, and I was enamored with the study of the immune system.

With all of the time we have social distancing because of the spread of COVID-19, I wanted to see if there was interest in people learning about the immune system and the brief intro on Instagram really took off, so today we’re going to take a brief tour of your immune system and how it protects us from bacteria and viruses.

Innate vs Adaptive Immunity

Your immune system has 2 major divisions: innate immunity and adaptive immunity. They’re made up of different cells and attack germs in different ways. Both are equally important, and both rely on each other for a comprehensive response to potential infection.

Innate Immunity – The first line of defense

The innate immunity is considered your first line of defense. It includes physical barriers like your skin and nose hairs which provide a wall to prevent entry from foreign invaders. It also includes things like mucous and stomach secretions which can entrap or inactivate proteins that may cause us harm.

From a cellular stand point, we have groups of white blood cells that are the first to show up whenever a bacteria, virus, or organism that breaks through the physical barriers. Your innate immune response acts immediately, and is usually responsible for the initial inflammation and swelling you see after you have a cut on your skin.

You can see the main players in the image below:

The different cellular components of your innate immune system

These cells form a general response to anything thing that isn’t part of your own body. Some cells like macrophages and neutrophils can literally eat bacteria on the spot.

A neutrophil engulfing a rogue bacteria.

Other cells like basophils, mast cells, and natural killer cells have granules that acts as chemical weapons that can contain or slow down an infection, or act as a controlled demolition if a cell gets infected.

All of these cells work together in harmony to contain or eliminate an infection before the big guns of the adaptive immune system get involved. They also act as the scouting report or reconnaissance team of the immune system because they teach your other immune cells what the germs look like, and the potential weaknesses of the germ.

In a perfect world, the innate immune response eliminates the threat and doesn’t allow germs to spread. The innate immune system encounters germs all the time and we don’t get sick, because the infection is small enough to keep to keep from spreading.

Adaptive Immunity – The Big Guns

If a virus or bacteria gets through the first line of defense, then adaptive immunity has to kick into gear which involves an extensive process of finding a germ’s weakness and creating an army of cells to dominate it.

A simplified breakdown of the adaptive immune response.

The adaptive immune response uses a different type of white blood cell called lymphocytes. Lymphocytes are like the equivalent of a military special forces team. Each cell is trained to recognize just one type of threat and to neutralize or eliminate it with brutal efficiency.

These lymphocytes can be divided into two types: T-cells and B-Cells. While these cells are very potent, they take days or weeks to develop an effective response to eliminate a new infection.


T-Helper cells are specialized T-cells which act like generals for the immune system. They patrol your body looking for any signs of the infectious organism, and they emit chemicals called cytokines to recruit the other immune cells to go in and attack infected cells or the organism itself. These are the cells that are destroyed by HIV, so when you lose these helper cells, it is extremely detrimental to the immune system as a whole.

Cytotoxic T-Cells are the immune systems demolition team. When the cells of your body get infected by a virus, it’s critical to prevent the spread of the virus that occurs when a virus overwhelms a cell. Fortunately, your cells have a self-destruct button that allows a cytotoxic T-Cell to come in and turn on the self-destruct switch which takes the viruses down with it.

How a Cytotoxic T-cell limits the spread of viruses.


B-cells are the immune cells that have the important job of making antibodies to fight infection. Antibodies are the immune systems primary weapon for overwhelming or inactivating a virus or bacteria.

While it’s not full proof, one of the ways a lab can tell if you are immune or have been exposed to a virus is by testing you for antibodies against the virus. For most cases, if you can produce antibodies against an infection, you are much less likely to get sick from that infection (HIV being one of the important exceptions to this rule)

When your immune system knows what type of infection to attack, it turns your B-cells into plasma cells which are basically antibody factories. Your plasma cells go on to flood your blood stream with these special weapons designed to target a specific virus, bacteria, or toxin to get an infection under control.

The evolution of a B-cell to a plasma cell for antibody defense.

Memory Cells

Probably the coolest part about about your adaptive immune system is that it can retain a memory of previous infections through memory cells. If you have successfully fought off a virus, you are unlikely to get sick from the same strain of the virus again. All of the activated Plasma cells and B-cells that fought off the germ will start to die off because you don’t want your immune system in staying in war mode all of the time or else you will be more prone to autoimmune illness.

Your B-cells and T-cells will just form memory cells that are not actively fighting, but just hanging out in your tissues. If your innate immune system or your memory cells encounter the same strain that made you sick before, the memory cells will quickly form activated plasma cells and T-cells

Instead of taking days or weeks to form a response, your immune system uses these memory cells to form a response within hours.

That’s why if you get sick from a strain of the seasonal flu, the same strain of the flu won’t make you sick again that season because these cells are ready to go.

Final Thoughts

This is just a very basic run down of the big players in your immune system. The levels of complexity that go into how this system operates are far beyond the confines of this article.

At the end of the day, here’s what matters:

  • Your body is constantly fighting off viruses and developing immunity and most of us have the tools to do this effectively.
  • Persistent stress is known to be immunosuppressive. Getting stress under control and avoiding panic is a critical part of having a robust immune response.
  • Besides Vitamin C and Vitamin D, we don’t really know what “Boosts” the immune system. Protect yourself from charlatans who are trying to boost your immune system when we really have no idea because of the insane complexity of this system.
  • The same things that you would do to maintain a healthy body are the same things that help your immune system stay healthy. Don’t simply try to do things to boost your immune system. Maintain a healthy body, don’t be an insane germaphobe so your immune system can have routine exposure, and maintain a reasonable amount of hygiene so your immune system doesn’t get overwhelmed.
0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published. Required fields are marked *

* Copy This Password *

* Type Or Paste Password Here *