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October 20, 2022 - January 9, 2023
They orchestrate others and directly activate your heaviest weapons.
T Cells are travelers that start their lives out in the bone marrow, where they mix and match the gene fragments that create their unique T Cell receptors, before they visit the Murder University of the Thymus to be educated.
what are the odds that a Dendritic Cell carrying a specific antigen, will find exactly the right T Cell that has the matching receptor for a specific enemy?
it is not just a single Dendritic Cell, in an infection at least dozens will make the trip. And on top of that the system is helped by fast travel. T Cells traverse the whole of your lymphatic superhighway once per day—imagine
The Helper T Cell can’t stay alone if it wants to help beat back the infection, so its first job is to make more of itself.
called the Clonal Selection Theory
Once enough clones have been made, the individual cells split into two groups:
Let us follow the first group right now!
they follow the chemical track to the battlefield as quickly as they can.
Although Helper T Cells don’t do any active fighting themselves, they considerably boost the fighting ability of the local defense cells,
are powerful and dangerous monsters and the decision to fully unleash their might should be the result of careful consideration.
Helper T Cells order them to become really properly angry,
Macrophages that fight in battle-frenzy mode are on a timer and will kill themselves after it runs out. This is another one of these safety mechanisms to make sure the immune system is limited to a degree.
When the battle is won, the last thing most Helper T Cells do at the battlefield is to kill themselves,
Except, a few don’t. Some Helper T Cells become Memory Helper T Cells. Whenever you hear that you are immune to a disease, this is what this means. It means that you have living memory cells that remember a specific enemy.
this makes the long trip of the Dendritic Cell to the lymph node unnecessary
There was a second group that remained
The mighty B Cell, your living weapon factories.
Cells are large, blob-like fellows that share a few characteristics and properties with T Cells, namely that they originate in the bone marrow and that they have to undergo the same brutal and deadly education—only it doesn’t happen in the Thymus but directly in the bone marrow.
they produce the most potent and specialized weapon the immune system has at its disposal: Antibodies.
are basically B Cell receptors
Once a B Cell is activated it begins to produce thousands of new Antibodies
to 2,000 per second.
B Cell activation and their life cycle are complicated.
they have to undergo a harsh and deadly education to make sure that they are not able to connect their unique receptors to the proteins and molecules of your own body. The survivors become traveling virgin B Cells, inactive cells that move through your lymphatic system every day, just like T Cells,
B Cells are very dangerous cells, so they need a strict two-factor authentication to be truly activated—one by the Innate Immune System and another one by the Adaptive Immune System!
A considerable number of bacteria pieces and carcasses float around at the site of infection, many of them covered by complement proteins.
inflammation ordered by the immune cells and caused by other dying cells diverts a lot of fluid from your blood to an infection,
it consistently washes them away, right into the Lymphatic System.
the lymph flowing through you is a liquid information carrier. And this information is headed towards the next immune system base, the megacities and intelligence centers of the lymph nodes.
The virgin B Cells look specifically for antigens they can connect to with their special and unique B Cell receptors.
There is no Dendritic Cell involved here,
a huge difference between T Cell receptors and B Cell receptors
Both T and B Cell receptors are each made to recognize a specific antigen, but your B Cells are far less restricted.
And B Cells do not need an MHC molecule, they don’t need to get a presentation from another cell like T Cells do. No, B Cells can pick up large antigen chunks (the turkey drumsticks) directly from the lymph that flows through your lymph nodes.
But there is more: B Cells do have more direct help from the Innate Immune System.
B Cells cannot just recognize the dead bacteria antigens, they also have special receptors that are able to recognize complement proteins.
So complement proteins attached to an antigen makes it about 100 times easier to activate a B Cell than it would be to activate it without the complement.
these simple mechanisms that happen on their own because the lymphatic system is always draining your tissue, are creating a relatively fast response.
What does this early activation look like? Well, first of all the activated B Cell moves to another area in the lymph node and begins cloning itself.
These B Cell clones begin producing Antibodies
Without a second step, without activation number two, most of these B Cell clones will kill themselves within a day.
And this one is provided to the B Cells by their colleagues from the Adaptive Immune System, or more precisely, by activated Helper T Cells.
In a nutshell, an activated T Cell needs to find an activated B Cell and BOTH cells need to be able to recognize the same antigen!
And only then, in this absurdly specific and seemingly impossibly unlikely case will your immune response fully be activated?
Basically, a B Cell takes a complex antigen and turns it into many processed, simpler pieces that are then presented to the Helper T Cell.
The B Cell is not just presenting a single specific antigen. It is presenting dozens or even hundreds of different ones in its MHC molecules!
Step 1: A battle needs to occur and dead enemies, which are big chunks of antigens (turkey drumsticks), need to float through the lymph node. Here, a B Cell, with a specific receptor needs to connect to the antigen.
This will activate the B Cell, which makes a lot of copies of itself and produces low-grade antibodies,
Step 2: In the meantime, a Dendritic Cell needs to pick up enemies at the battlefield and turn them into antigens (wieners) which are put in the MHC class II molecules (hot dog buns) and travel to the T Cell dating area in the lymph node. Here it needs to find a Helper T Cell that is able to recognize the antigen with its unique T Cell receptor (eat the wiener from the bun). If this happens the Helper T Cell is activated and makes a lot of copies of itself.
