The military training movie inside you
Ready for recruits
Our bodies take homeland security very seriously.
The immune system is made up of organs, glands, lymph, and specialized cells programmed to carry out specific tasks to identify, attack, and kill foreign invaders.
T cells are one type of immune cell tasked with finding and killing invaders. Before they can carry out special ops missions, they go through rigorous training, Top Gun style, in your thymus, a small gland near your heart.
Here’s a little bit about what happens:
T cells are first created inside our bone marrow.
The baby T cells then migrate from bone marrow to the thymus, where they go through multiple rounds of training.
In Phase 1, the thymus tests the T cells ability to grab onto things — crucial during combat when fighting foreign bodies, because they attack by attaching via a lock and key mechanism.
Some T cells won’t pass this phase. They’ll be killed off.
Phase 2 is about teaching the T cells what to attack and most importantly, what NOT to attack.
This is where things get philosophical. The T cells key to success is their ability to detect what is self and what is not self. They must attack microbes that are foreign and specifically leave everything else that isn’t foreign (our own cells and tissues) alone.
How does the thymus test these T cells’ ability to know the difference between ourselves and not ourselves? It creates a “shadow self” (link) - a fake version of every type of cell in the body to fake out these newly formed t cells and put them to the test. If they attack the fake “shadow self”, they’re gone - the thymus orders them to die by suicide.
The T cells that successfully discriminate between foreign and domestic pass training. They get released into the body to carry our their mission of protecting us from foreign invaders for the rest of their little T cell lives.
The drama of it all.
