I've had allergies my whole life, but I've never thought about immunity until I got kids. This topic got me interested when I've seen the constant rollercoaster of disease that my kids get while attending kindergarten.
This book has amazed me in many ways. It covers all the complexities of the immune system and the pathogens that attack us - in a nutshell.
If you ever wondered why are you coughing up brown/green/yellow stuff a few days after your kid sneezes at your - then this is a book for you.
My recap
Our immune system is a complex and multilayered mechanism composed of seemingly "dumb" parts.
When our body gets attacked by a pathogen the immune system has processes in place to stop the invasion.
It starts with the Innate immune system, consisting of macrophages (massive cells that devour attackers), neutrophils
(crazy spartans that can explode if shit hits the fan and shred the attackers with spiky proteins), dendritic cells (scouts that collect information
and trigger the adaptive immune system). Innate immunity is a great generalist player, but some attacks need more specialized forces to be stopped.
Enter the Adaptive immune system. Our body constantly produces T-Cells that are good against a SPECIFIC attacker. And it's building
a sort of a library of weapons. Your body now has weapons on the shelves that can tackle species of viruses that are not even born yet.
These weapons (T-cells) lounge around our body (each of them with low body count), until they are called to arms.
When the invasion happens, the scouts of our system, the Dendritic cells, gather the intel from the battlefield and carry it around our body, searching
for a matching weapon (T-Cell). Once found the T-Cell starts replicating and storms the battlefield.
Everyhing in our body boils down to proteins. Super tiny building blocks. Each protein has a specific shape that can connect to a receptor with a matching socket.
Making these connections is what makes all those insane complexities and what gives our immunity such power.
Reading notes
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Immunity emerged 0.5 bil years ago. Humoral immunity, bodily fluids (still exists today)
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Main task of the immune system is to preserve homeostasis - a lot of things can go wrong
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Cells are filled with proteins
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Proteins are like 3d puzzles that interact with other proteins
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Sequences of interactions of proteins are called pathways - and pathways are what the cell can do
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Cells are protein robots driven by biochemistry
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Complex interactions between "dumb" protein result in less dumb cells
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Complex interactions between less dumb cells result in pretty advanced and powerful immune system
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Emergence - entities have properties that greatly surpas the properties of the single parts the entity
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Immunity is consisting of two main parts: Innate immunity and Adaptive immunity
Inate immunity
- Members of the Innate immunity:
- Macrophages (eats pathogens, cleaning service)
- Neutrophils (crazy spartans, contain granulas that shred pathogens when they explode
- Dendritic cell (ingest pathogens and carry the snapshot of the battlefield to trigger the Adaptive immune system with the correct information)
- Inflammation
- universal immune response to any kind of damage or invasion
- the goal is to stop spreading and helps remove damaged cells
- serves as a highway for immune cells to get to the attack site
- makes the blood vessels porous so they can pass proteins, immune cells, salts ...
- accute inflammation = good; chronic inflammation = bad (50% deaths are caused by chronic inflammation)
- Cytokines - proteins used for communication and navigation of the immune cells via receptors
- When Dendritic cells deliver the information the Lymphatic system starts to produce various weapons
- T-Cells: multiple roles, help out in the defense by enraging Macrophages and Neutrophils
- Antibodies: small proteins that glue themselves to the attackers so they are slower and easier to detect
- Thymuss trains the immune cells - millions of T-Cells are created every day, only 2% survive the Thymuss training
- The main requirement for the T-Cell to get out of Thymuss is to not be able to attach to the proteins that make up our body
Adaptive immunity
- Adaptive immunity activates when the Dendritic cell carries antigens from the battlefield and presents them wrapped in the MHC protein
- fun fact: MHC has differences between people and we are attracted to people with different MHC
- T-Cells
- they are created in the bone marrow and go through Thymuss that determines if they are ok or not
- there are multiple subclasses of T-Cells
- they travel around the body and on various stops across the Lymphatic system they would stop and ask "somebody needs me?"
- when they find a Dendritic cell with a corresponding receptor (meaning an antigen wrapped in a MHC that they can attach to) they get activated and start replicating
- when they replicate they are separated into two groups; the first group heads out to the battlefield (it takes ~5 days for them to reach the battlefield); the second group heads out to wake the B-Cells
- to activate B-Cells, a two factor authentication needs to happen (the B-Cell itself needs to have a receptor for an antigen and they need to have an antigen connected to that receptor PLUS an activated T-Cell needs to confirm the activation)
- for a B-Cell to become a plasma cell that produces perfect antibodies they go through the process of mutation, where cells which receive weaker cignal from the antigens are dying and cells which receive a stronger signal continue replicating and mutating
- Antibodies
- IgM (they get deployed early, can activate the complement system)
- IgG (there exists several subclasses; they cover the pathogens like a swarm of flies; help the phagocytes to devour pathogens; it gets passed down from the mother to baby via placenta)
- IgA (most spread antibody; cleans up mucous membranes; can't activate the complement system; a lot of them get produced in the gut; mother passes down to baby via breastfeeding)
- IgE (original purpose is to battle large parasites - parasitic worms; the cause god damn allergies)
Viruses
- we know of ~200 species of viruses that can attack humans
- their main advantage is super fast replication and mutation
- they use the Troyan horse tactics - the longer they are undetected the better
- Innate immunity is not efficient in battling viruses; other strategies need to be used
- the goal of the immune system is to detect viruses as early as possible
- massive role is played out by cytokines
- cells have the ability to start producing a specific type of cytokines when they realise that something is trying to take them over - Interferons
- Interferons come out of cells and notify neighbour cells
- some infections can be stopped fully by Interferons alone
- the next step in detection are special Dendritic cells that travel the body and look for alarmed cells, when found the Dendritic cell becomes a super producer of Interferons
- Pyrokines - they can pass to brain and bump up the thermostat so the body starts to heat up
- our cells are larger than viruses and bacteria, so they can survive higher temperures for a longer time
- Killer T-Cells
- they get activated with help of Dendritic cells and Helper T-Cells
- they travel the body and look through "windows" of our cells (cells present their contents via MHC 1 molecules)
- if an antigen from a cell matches a Killer T-Cell receptor, the Killer T-Cell orders the cell to self-destruct (Apoptosis; a clean and nifty way for a cell to kill itself)
- Natural Killer T-Cells
- they kill the cells that don't have MHC 1 molecules (or "windows")
- it's a cool way to find invaders, as our cells need to have those windows
- After the infection is over Memory T-Cells are created
- When the same pathogen arrives the next time, the immune system can skip the two factor authentication - so the response is faster
- Measles attach the very Memory T-Cells, and they can wipe out everything that the Immunity has learned up until that point
Allergies
- They are caused by IgE antibodies
- When an allergen enters the body, and the B-Cells that are found in skin, lungs and guy can attach to some of the protein with their receptors they start to produce IgE antibodies
- First encounter of the allergen doesn't cause any visible reactions
- IgE antibodies that get produced for that first time get collected in the Mast cells; that keep them like a bomb full of nails
- With the next encounter of the allergen Mast cells start pumping out the nails
- The nasty symptoms of allergies start to emerge
- When the Mast cells get emptied, the story continues by Basophiles which ensure the longer reaction
- And lastly the Cytokines and the Basophiles activate the Eosinophiles that are in the bone marrow - to continue the agony
- IgE antibodies are originally meant to fight large parasites (parasitic worms)
- The rise in allergies and auto immune diseases is suspected (but not 100% true) to be caused by lack of exposal to the communal bacteria that live with us for millions of years
"Boosting" immunity
- to boost immunity iss a wrong sentiment
- the immunity should be balanced (homeostasis)
- boosted immunity would mean stronger reactions - immunity can kill us faster than any pathogen
- to help balance out the immunity we can take in proper food (micro nutrients help out our body build out our cells)
- exercise - helps the bloodflow in all parts of the body (again helps get the nutrients get to the places they are needed to build cells)
Missing stuff
- [ ] Missing notes about complement system
- [ ] Missing notes about bacteria