Immunity: definition and components

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Immunity is the way your body keeps you safe from disease. Your immunity is supported by your immune system, which is a complex system of cells, specialised proteins and tissues which protect you from potentially harmful invaders like bacteria and other microbes.

Read on to learn more about what immunity is, why it’s important, what components make up your immune system and the different kinds of immunity.

What is immunity?

Immunity is your body’s ability to resist and fight infection and disease. This is done by your immune system. Your immune system is made of several special components that work together to protect your body from potentially harmful foreign substances that you may encounter in your environment.

Why is immunity important?

Your health relies on your immunity and your immune system. It is crucial for keeping you from getting sick by keeping potential infections under control.

Some people struggle with immunity and may have a weakened immune system or are immunocompromised. This means that their immune system does not function as it should, and it has a reduced ability to fight infections and viruses. Common causes include cancer, HIV/AIDS and transplant patients (who may be taking medicine to suppress their immune system).

In some cases, your immunity may be too active, resulting in an autoimmune disease. This is when your immune system targets and attacks itself. Having an overactive immune system is also what causes allergies, which happen when your immune system attacks usually harmless substances like pollen.

What are the components of immunity?

The biggest component of immunity is your immune system. Your immune system is a complex collaboration between cells, tissues and proteins that work together to protect your body against microbes, viruses, and other harmful substances.

The immune system is formed a range of parts, including:

  • Antibodies – antibodies work to fight microbes by recognising antigens on the microbe’s surface. They may then mark the microbe to be destroyed by other cells.
  • White blood cells – white blood cells move through your body searching for foreign pathogens like viruses and bacteria. They then launch an immune attack upon these substances.
  • Thymus gland – makes white blood cells known as T lymphocytes, or T Cells. They are responsible for fighting infections.
  • Bone marrow – the tissue found inside our bones which is a major site of white blood cell production.

The lymphatic system, although not solely part of your immune system, is also very important. It’s made up of your lymph nodes and lymph vessels. It helps to move fluids from tissues into blood circulation and helps gets rid of waste that cells make. It also contains structures called lymph nodes that can help make or activate lymphocytes, which are a kind of white blood cell that help to fight infection.

Another important tool that your body has for keeping you well, are the physical barriers which keep harmful pathogens out of your body. This includes things like the cough reflex, your skin, the digestive system and stomach acid (which destroys ingested pathogens), mucus (which traps particles) and the antimicrobial enzymes found in tears. These physical barriers are your body’s first line of defence against illness.

All of the components of your immune system need to be working properly to give you good immunity and to ensure your body launches an immune response process when it encounters harmful foreign substances.

What are the kinds of immunity?

Immunity can be split into several different subgroups. The two main kinds of immunity are innate immunity and adaptive immunity. Adaptive immunity is then split into active and passive immunity. Active immunity can be grouped into natural or vaccination-induced immunity, and passive immunity is grouped into maternal immunity and artificial immunity.

All kinds of immunity mean that your body has an active response to harmful substances.

Innate immunity

Adaptive immunity


Active immunity

Passive immunity






Innate immunity is the defence system you were born with. This includes things like inflammation, fever, and the histamine response your body can produce when you encounter an allergen. Unlike adaptive immunity, your innate immunity doesn’t involve antigens. If a pathogen manages to evade your body’s physical barriers and your innate immune system, it may also encounter the adaptive immune system.

Adaptive immunity, sometimes called acquired immunity, is when the immune response involves antibodies. This can be either through active or passive immunity.

Active immunity happens when your immune system comes into contact with and recognises pathogens with antibodies that help to recruit immune cells, help destroy or remove foreign pathogens. This can be through natural immunity, which happens after you’ve been exposed to a pathogen naturally, or vaccination-induced immunity, which is when you were exposed to a dead or weakened version of the disease through a vaccination (also called immunisation).

Through these kinds of active immunity, your body can learn to defend against a virus that it encounters several times, acting as a kind of “memory”.

Conversely, Passive immunity is when you are given the antibodies rather than producing them yourself. This is split into maternal immunity (for example a newborn baby receiving antibodies through their mother’s breastmilk) or artificial immunity (for example, hospital treatment with blood products that contain antibodies).

It’s important to make sure you’re looking after your body to ensure the proper function of your immune system. There are a lot of resources available for supporting your immune system. One way you can look after it is to ensure you’re eating a healthy, balanced diet which includes plenty of fruits and vegetables so you’re getting all the nutrients you need every day. For more information on how you can look after your immunity, why not check out our blog on immune support?

If you want to support your immune system you could try adding Berocca Immuno to your daily routine! Berocca Immuno contains 10 immune support vitamins and minerals* to help support the normal function of your immune system. Simply drop Berocca Immuno tablet into a glass of water, wait for it to fizz, and enjoy!

*Berocca Immuno contains vitamins D, C, A, B6, B9 & B12, and minerals zinc, copper, iron & selenium, all support your immune system.


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*Contains caffeine which helps improve alertness. Do not exceed 400mg of caffeine per day. Not suitable for those pregnant or breastfeeding.