📝 Immune, by Phillip Dettmer
This is an incredible book and the brief notes I took below do not do justice to how well it is written.
White blood cells is a too vague a term for the varied kinds of defenses we have.. Too simplistic.
Innate Immune System
- First line of defense
- Can differentiate Self vs other. Anything that is not Self is a threat
- Simple blueprints for vast patterns of attacks (all bacteria for example)
- Activates the 2nd line of defense if needed
Important players:
- Macrophage - Think of them as giant tanks: they engulf their prey and break them down. will come and rip cells to pieces.
- Dendritic cell - These have tentacles to probe what is going on, and pick up critical bits of information and send it all the way to the thymus where the Adaptive Immune system analyzes the signatures and prepares targeted attacks.
- Neutrophil - explodes and creates nets to trap everything around it. Dangerous to self as well, not just the other. So they have a short life.
- Basophil - causes inflammation, what else?
- Eosinophil - related to allergies I think
- Mast cell - large cells that cause inflammation
- Natural killer cell - this is trained to kill pathogens and infected cells but unlike T cells I think they are already trained and ready to deploy in the Innate part of the immune system. They see if MHC class 1 molecules are present in a cell. If not, they tell the cell to kill itself. Reason: some viruses that take hijack a cell have a camouflage where they hide the MHC class 1 and therefore from the outside it is not clear what is being built inside the cell. So absence of this information implies a hostile takeover.
Adaptive Immune System
- Blank slate, filled up over a person's lifetime
- Targeted attacks, like a large encyclopaedia containing every possible threat
Important players:
- T cell - Helper, Killer, Memory, Regulatory T Cells etc. Helpers enrage macrophages and accelerate their work, coordinate orchestrate and activate the heavy weapons
- B cell - once antigens are presented to virgin b cells, it makes copies of itself, breaks down the antigens into smaller pieces and presents them in its 'window' i.e. MHC class 2 molecules. Dendritic cells pick up these and activate corresponding T cells. Then when a B cell later meets its corresponding T cell, it gets activated into a plasma cell (?)
- Plasma cell - creates antibodies and releases them rapidly in the infection
- MHC class 1 molecules: It is a 'window' on each cell to see what kind of proteins it is making.. and if the immune system sees something it doesn't like (e.g. a virus has taken over the cell and is making copies of itself), it tells that cell to kill itself.
- Antibodies - really tiny spikes that rip apart pathogens.
Skin
Constantly created and pushed upwards. Then there is a spiky layer of 'defensins' which can rip holes in specific targets like bacteria and fungi.
Upper layers are all dead cells, so not hospitable for viruses. An acid (and salty layer) above it, which is again very corrosive.
pH – Power of Hydrogen – each -1 implies 10x more hydrogen I.e acidic. Similarly high pH I.e. alkaline means there is 10x less hydrogen ions. Both less and more pH are corrosive to life.
The Immune System
Things that 'boost' the immune system: nothing really, boosting is bad if you've read this book .. The immune system will turn on the body and needs to be carefully regulated and released only during serious attacks.
So a healthy diet (incl fiber) is all you need. For preventing allergies it appears that breast milk, natural deliveries and a farm-like upbringing (cows/dogs running around) make a difference.
On the other hand, things that weaken or suppress your immune system: stress! smoking.
Apoptosis
Cells neatly kill themselves in a self recycling manner. Killer cells do their job by sending a signal to infected cells to do this. They look through a 'window' to see what kind of proteins these cells are building. If they see the bad kind e.g. Viruses, they tell the cell to self destruct.