What is Immunity?

Emma Lloyd

Immunity is a state in which the body is protected from infectious disease. It is conferred by the immune system, a complex network of cells, tissues and chemicals that fight infection and kill organisms when they invade the body. There are three categories of immune protection, all of which help protect the body from infectious diseases. It can be innate or acquired, active or passive, and natural or artificial. These categories can mix and match to produce, for example, natural passive or artificial passive immune protection.

Exposure to infectious organisms triggers an active immune response.
Exposure to infectious organisms triggers an active immune response.

The category of innate or acquired protection refers to the type of immune response that is mounted by the immune system. An innate immune response is not specific to the pathogen to which the system is responding, and it happens almost immediately when an infectious organism invades the body. In contrast, an acquired immune response is specific to the pathogen and can take several days to build up. The acquired immune response also involves the development of immunological memory, a state in which the immune system can quickly mount a response to an infectious organism that it has previously encountered.

Vaccinations can help boost immunity.
Vaccinations can help boost immunity.

Active or passive immune protection is determined by the way in which the protection is conferred. Protection that is active is conferred by contact with an infectious organism or a vaccine. This provokes an active immune response in the person who comes into contact with the organism. Passive immunity refers to the fact that an individual is protected, even though his or her immune system has not itself mounted a response. For example, the trans-placental transfer of antibodies from mother to child is a type of passive immune protection. Another example is the transfer of antibodies from mother to child in breast milk.

A mother transfers antibodies to her baby through breastfeeding.
A mother transfers antibodies to her baby through breastfeeding.

The third category, natural or artificial immunity, refers to whether the protection has developed with or without intervention. For example, trans-placental antibody transfer is a natural process, because it has occurred solely though an interaction between mother and fetus. If, after the baby was born, an antibody injection was administered, this would be an example of artificial protection, because the antibodies have been removed from one individual, purified, then injected into another. Vaccination is another example of artificial immune protection and is also an example of active acquired protection.

Vaccination and passive immune treatments are not the only ways to confer immune protection. It can be improved in many other ways, as has been demonstrated over the course of history. For example, improvements in sanitation, diet and pest control have contributed to the reduced severity of diseases and the increased life expectancy that people in developed countries enjoy now, compared to that of several hundred years ago.

Some babies may experience a fever as a result of receiving a vaccination.
Some babies may experience a fever as a result of receiving a vaccination.

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Discussion Comments


Did you know that there's also a close connection between protein and immunity?

Proper levels of protein are essential for producing white blood cells, one of the main components of the immune system.

Without having enough protein in your body, having poor protein absorption abilities, you could be riding for a fall with your immune system.

That's why it's important to eat a wide variety of foods that support each other. For instance, just upping your protein intake is good, but matching that increased protein intake with ginger is even better, since the ginger helps to break the protein down, which makes it easier for your body to absorb.

I'd suggest that anybody interested in boosting their immunity should talk to a nutritionist before they talk to a doctor -- a proper diet can go a long way in improving your health, and it's often a lot cheaper than medication.



Can anybody tell me what exactly is the importance of T cells for immunity? I keep hearing people talk about T cells, but I can't seem to get my head around what it is exactly that they do, or why they are important.

Could you help me out?


Immunity is one of those things that it's easy to take for granted -- until you get sick. Then you realize just how important immunity is to the body.

Fortunately, it's easy to keep your body in good shape, immunity wise.

First, and most importantly, get your vaccinations! Vaccinations and immunity go hand in hand, understandably. Though some people try to connect getting a vaccine with becoming immunity compromised, it's simply not true.

Nutrition also plays a key part in boosting immunity. By getting your five fruits and vegetables a day and eating a wide variety of foods, you can go a long way in boosting your innate immunity.

Finally, monitor yourself for a reduced immunity response. Just like you'd keep an eye on your car's function, pay attention to your body and listen to what it's telling you.

If you seem to be getting sick more often than usual, it could be your immune system telling you that it needs a little TLC.

So just remember to follow these few simple steps, and you'll go a long way in keeping your immune system active and effective.

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