You and what army?

Did you know we offer a Winter School course in Communicating Science? If you’re interested in science writing for both specialist and non-specialist audiences, presenting to communicate science and the use of emerging online social media in science communication, this is a great course for you. If you’re interested, check out “Communicating Science” in course outlines for more details.

Over the coming weeks we’ll be showcasing blog posts written by Communicating Science students during their course last year. The next blog in the series is “You and what army?” by Jacinta Frater.

The answer is simple- me and mine.

You have your own personal army. Every moment of every day your own loyal soldiers are fighting and dying for you. I’m talking about your immune system, the different cells through your body that act as a defence system against infection and bacteria. And I’ll tell you why your best friend can also be your worst enemy.

But what exactly is the immune system?

Well the army analogy is actually a pretty good way of looking at it. The immune system is made up of many different types of cells that form a complex and ever changing network throughout your body. Different cells focus on communication, killing or both. I’m going to cover some of the most common types of immune cell and some of their secretions then take a look at two examples of ‘friendly fire’ and why no matter how amazing your personal army is, armies cause destruction, and sometimes they pick the wrong target.

B cells

These are your sentry posts. They secrete antibodies (Ab), which act as an alarm system. Each B cell secretes a different Ab that is in charge of checking for a different problem.

Ab- antibodies or immunoglobulin (Ig) are signals. Their job is to grab a hold of something that doesn’t fit and go ‘here I am HERE, COME HERE, SOMETHING”S WRONG!!’ Basically they set the alarm off. Each Ab checks for different things, or concentrates in different parts of the body. IgE checks for parasites, IgA concentrates in body fluids like tears and spit and guards the respiratory and digestive tract ect

T cells

There are two different types of T cell;

Helper T cells; these cells help regulate and coordinate the immune system. They signal to B cells and other T cells and some call in phagocytes (I’ll talk about them later). Essentially Helper Ts join up with B cells to make up the signal system. They span across the body and pass messages back and forth- things like- Ab x needed in the lower lungs or Killer Ts needed here stat!

Killer T cells; these cells do your dirty work for you. They are your own personal SWAT team, constantly patrolling your body. If they come into contact with a cell that needs to die they kill it. No second chances, no begging for mercy, just a quick silent death. There are 2 subtypes of Killer T cells; Natural Killer cells who look for the antigens your body produces naturally and attaches to all its own cells, if they find a cell without these antigens they kill it. The other type is Cytotoxic T Lymphocytes (CTLs), these look for cells that have been flagged by an antigen from a B cell, they are particularly good at killing cells that have been invaded by a virus before the virus can spread.



The most common phagocytes are macrophages; think of these cells like ghosts (or your army’s bureaucracy), they are large white cells that swallow and consume foreign things and microbes.


There are several different types of granulocytes that carry a set of chemicals called granules around. They use these granules to destroy microorganisms like parasites by spraying them. For your body they act like crop dusters that spray the parasites with chemicals. Neutrophils are both granulocytes and phagocytes; they have granules but they consume the microorganism and break it down inside, like the acid in your stomach breaks down the food you eat.


Cytokines are the chemical messengers that the immune system uses to talk to itself. All sorts of cells in the immune system release cytokines. They use then to turn cells on, tell them where to go and even to tell themselves to keep talking.

Friendly Fire

And now to the dark side- autoimmune diseases or disorders.

Autoimmune disorders are when your immune system mistakes your own cells as foreign invaders and begins attacking your own body. They include a wide range of diseases and conditions that you have probably already heard of, along with some that you haven’t but are particularly nasty all the same. The causes are complex and in many cases unknown, as are the triggers.

Today I’ll cover the top 2 that you are likely to have heard of;

Type 1 Diabetes

So everyone knows that type 1 Diabetes is when your body doesn’t produce the insulin you need to regulate your blood sugar levels. But why does the body not produce insulin? Well there are different causes in different people but one of the most common is that the person immune system attacks the insulin producing cells (B-cells) in the pancreas and destroys them. You know your friend SWAT squad the T cells? Yeah, sometimes they get confused and the B-cells of your pancreas can come under friendly fire.

Multiple sclerosis

This is an immune disease that targets the central nervous system. The trigger is unknown but the immune system starts to attack the myelin or protective sheath that surrounds the nerves in the brain and spinal cord. The disease is unpredictable and variable and causes a progressive breakdown of communication by the nerves throughout your body resulting a loss of motor control and cognitive problems amongst other issues.


But although our immune system can destroy our lives, and even kill us, it is still our best defence against the rest of the world. What we need to focus on now is in learning more about how all the components of the immune system work together and interact so we can learn how to avoid the friendly fire.


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