What is your immune system and how does it work?

Key points

• Immunity relates to many parts of your immune system.
• The immune system is extremely complex and has multiple contributing pathways. 
• White blood cells protect the body from infection and make up around 1% of your total blood.
• If your immune system is weakened, it may not respond as it should.

Have you ever wondered how you manage to catch a cold? Or how your kids can have a cold, but you somehow avoid it despite them sneezing constantly in your face?

The word immune system is thrown about a lot, but what actually is it and how does it work? 

The truth is the immune system and immunity are rather sophisticated. There are many interesting facts about the immune system that you would likely be surprised to learn.

While your neighbour may swear by vitamins for immune system health, it’s much more complex.

Let’s look at the ins and outs of immune health to help you understand what affects your immune system and how it works.

What is your immune system?

The immune system is made up of many different elements. This includes organs such as the spleen as well as white blood cells, antibodies, bone marrow and the lymphatic and complement systems.

Your skin and bodily fluids like your lung’s mucous lining, stomach acid, saliva and tears also play a role in protecting you from germs (bacteria, viruses and fungi).

Interestingly, there are two main parts to your immune system. The first is the innate immune system, which is basically your first line of defence. When a germ or virus attempts to enter your body, the innate immune system kicks in to try to prevent that from happening.

If the innate immune system fails, it calls on the adaptive immune system for back up.

While the innate immune system launches a generic response, the adaptive immune system is much more specific. It’s also slower to respond. It takes time to formulate a response that will target the particular bacteria or virus. 

What is immunity?

As the first line of defence, the innate immune system responds quickly to threats. It’s also sometimes known as the “nonspecific” immune system. The generic or nonspecific nature of the immune system means that it doesn’t retain any memory of germs. That’s not to say that it doesn’t do an amazing job. It just does an amazing job at what it’s designed to do.

The adaptive immune system works hand-in-hand with the innate immune system. There isn’t a germ that the adaptive immune system forgets. If a germ targets your body for a second time, the adaptive immune system will remember it and knows how to respond more quickly. This is sometimes referred to as acquired immunity. 

Immunity is what may stop you from catching a virus from your kids. If you’ve already had the virus, your immune system may know how to respond quickly to prevent it from taking hold. 

How does the immune system work?

We’ve already touched briefly on how the innate and adaptive immune systems work. But buckle up, because now we’re going to dive a bit deeper into the inner workings of your immune system.

Firstly, imagine that all around your body are tiny little soldiers. They’re on your skin, in your mucous membranes (in your nose and mouth) and they’re in the majority of cells within your body. These soldiers are always armed and ready, patrolling your body for any signs of germs that shouldn’t be there. These germs and toxins are called antigens. 

As soon as an antigen is identified, the soldiers spring to action like an angry nest of ants. They use all the tools in their arsenal to hold the unwanted intruder at bay. 

Behind those soldiers is a second line of soldiers. They’re more strategic and spend time analysing the attack methods of the antigen. This is the adaptive immune system in action. Once they have formulated a plan of attack against the antigen, they launch their response to destroy the antigen and remove the threat, germ or infection. This is when the innate immune system soldiers go back to their patrol job. 

Once the threat from the antigen has been suppressed, the adaptive immune system soldiers keep a record of the antigen and how it behaves. These memories are called antibodies.  

This is how a healthy immune system works. There are many other factors that may inhibit the immune system. For example, the impact of stress and the immune system are documented.

What do antibodies do?

Antibodies can be found in your blood and other bodily fluids. As already mentioned, they contain the memories of how to attack germs or antigens.

If an antigen enters your body after your immune system has already fought it off, the antibodies deploy to fight it off. They know the modus operandi of the antigen and they have the exact weapon to destroy it. Pretty incredible, isn’t it?

What do white blood cells do?

There are many different types of white blood cells in your body. White blood cells are also known as leukocytes.

Each type of white blood cell plays a very particular role. Some white blood cells play an antigen-neutralising role in the immune system. How do they do that? You could say that white blood cells eat antigens for breakfast.

As the white blood cells encounter a germy antigen, they try to destroy it. Whatever parts of it they can’t destroy are left on the surface of the white blood cell for the immune system to deal with. 

White blood cells only make up about 1% of your total blood. While they’re in the minority, they certainly play a role. A good white blood cell count is one of the many signs of a strong immune system.

Maintaining a strong immune system

Now you know how a strong and healthy immune system works. If your immune system is weakened or suppressed for whatever reason, it may not respond as it should.

So, what can you do to maintain a strong and healthy immune system? 

“There is no magic pill,” says GP, Dr Jill Gamberg, “The key to a healthy immune system is in taking care of yourself.”

Dr Jill suggests:

• getting a good amount of sleep
• moving your body more to enjoy the positive effects of exercise on the immune system
• eating a nutritious diet of wholefoods
• keeping stress levels as low as you can
• staying socially connected
• avoiding things such as smoking or excessive alcohol

“If you’re sick, stay home,” says Dr Jill, “Coughing and sneezing into your elbow is also good etiquette. Washing your hands more and touching your face less can also help you to look after yourself.”

The amazing immune system

It’s pretty cool to think that while you’re going about your day, your immune system is potentially in action fighting off germs. The fact that we’re designed with an in-built germ fighting mechanism is actually rather remarkable.

The field of immune health is one that’s always evolving. Researchers continue to do their thing to uncover new and fantastic information about how our body protects itself from germs and viruses. For example, do you know which herbs are adaptogens and the role they might play in your immune health? Or if the gluten free diet has any effects on the immune system?

At the end of the day, we all want to be well. By learning more about your immune system and how it works, you’re taking the right step forward in an empowered health journey. 

Related:

• How to boost your energy levels when you’re tired
• Sleep for women: how to get better rest and improve your health
• Is walking good for you?

Dr Jill Gamberg is a General Practitioner and one of the first Australian Lifestyle Medicine Physicians whose goal is to help prevent disease and maintain wellness with evidence-based practice, and to passionately improve health literacy.

Reviewed by the healthylife Advisory Board September 2021.