What makes up my immune system??
Our immune systems can use different approaches to protect us against invaders, but what are these approaches and how do they work?
Here is our simple summary, including:
- The primary immune response, also known as the innate immune response.
- The secondary immune response, also known as the adaptive immune response.
- The cells involved, such as phagocytes, B-cells, antibodies and T-cells
- What is long term immunity?
First glance or round two?
The first time you are exposed to a disease-causing organism (like a virus or bacterium), your body launches its primary immune response. This response is generic and can be used against any pathogen you come into contact with – a bit like using a citronella candle to keep away all bugs.
The second time you are exposed to that organism, your body has learned about it and can launch a more targeted, secondary immune response on it. Often this means you don’t even get infected or feel unwell – this is more like using a specific anti-mosquito spray.
Phagocytes and the innate immune response
Phagocytes are important cells that are part of the general, first line of defence. These cells sniff out the chemicals left behind by bacteria as they travel through the body, and “eat” the bacteria to destroy them. Very much like an immune system pac-man.
In addition to these cells, the body can also employ methods like a fever – while you do feel poorly, higher body temperatures improve the efficiency of immune cells and may slow down pathogens.
B Cells and Antibodies
B Cells are super important in helping a body remember pathogens you’ve come into contact with before. If you are reinfected with the same pathogen, B cells recognise it from molecules on its surface and warn the rest of the immune system about its presence.
B Cells also produce plasma cells, which in turn release antibodies. Antibodies are specific to one particular pathogen, and fit them like a key to a lock. They are either attached on cells, or flow freely in the blood.
T Cells come in two forms: helper cells and killer cells. Helper cells release molecules that help other cells to recognise and track the pathogen around the body. Killer cells track down the cells of your body that are infected with the pathogen and release chemicals to remove those cells to stop further infection and spread.
Long term immunity
Although your body has these cells that remember pathogens you have encountered before, they are not always for life. Some pathogens can mutate to get around the immune memory, and other times your body’s response will dwindle over time.
This is different for each potential infection, and is the reason why people can have the same illness twice, or why some vaccines need booster shots.
Equally, some of the knowledge from one disease can sometimes be applied to related pathogens if they are similar enough. This is known as cross-reactivity and can sometimes mean you get less sick the first time you encounter a pathogen.
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