Your Body Already Has a Defense for Germs That Do Not Exist Yet
Billions of unique commander cells wait in your lymph nodes, and scout cells search them for a match.
Kurzgesagt – In a Nutshell · How The Immune System ACTUALLY Works – IMMUNEYou already carry a weapon for germs a century away on Mars.
That is possible because you carry billions of helper T cells, a kind of commander cell in your immune army, and each one is unique. The body's helper cells are believed to cover nearly any germ, from the Black Death, the coronavirus, and diseases that do not exist yet.
Your body finds the right one through a delivery and search system. While front line soldiers are fighting at a wound, a dendritic cell, the intelligence officer of the immune system, collects samples. It rips bacteria into tiny parts and coats itself with the scraps.
The loaded dendritic cell then leaves the battle and enters the super highway that connects your tissues to your lymph nodes, the headquarters of the immune system. There it goes looking for one helper T cell, not just any helper T cell, but the one that happens to carry just the right weapon for those bacteria parts.
The search is physical and slow. The dendritic cell, still covered in bacteria parts, rubs itself against every helper T cell it meets. Most are not interested. After hours of checking, one helper T cell finally recognizes the fragments, and the dendritic cell activates it.
Activation means copying. The activated cell divides repeatedly until there are thousands of identical copies. Only then does your powerful second line of defense rise, and it rises very slowly.
You do not need to have met a germ to be ready for it. Somewhere among those billions of commanders, the match is already waiting.
Questions people ask
Where are lymph nodes, and what do they do?
Lymph nodes are small, bean shaped filters found in places like your neck, armpits, and groin. They trap germs and damaged material carried in lymph fluid, and they house large numbers of immune cells so scouts and commanders can meet.
Why does it take hours just to find the right helper cell?
A few hours is normal for the first match because one scout must physically test many helper T cells one by one. Once the match is found, building thousands of copies takes additional days, which is why the stronger second defense is powerful but slow.
How does the body make billions of different weapons in the first place?
Your body shuffles pieces of DNA as immune cells develop, creating billions of different receptors by random combination. Each new helper T cell ends up with a different shape, and cells that would attack your own body are mostly removed before they are released.