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Once Mast Cells activate and degranulate, they also release cytokines that call for allergy reinforcements by another special cell:
The Basophil. Basophils patrol the body in the blood until they get called in. They also have receptors for IgE that they charge up after the initial exposure to the antigen.
These two cells are responsible for the immediate hypersensitivity.
The Eosinophil makes sure that the symptoms of an allergic reaction stay around for a while—only
IgE Antibodies
are the immune system’s superweapons against large parasites that are too big for your phagocytes, your Macrophages, and your Neutrophils to swallow.
when the worm is recognized for the first time—probably close to the border regions of the body—the special B Cells stationed near the skin or in the respiratory or intestinal tracts begin the preparation by making large amounts of IgE Antibodies. These IgE Antibodies “prime” your Mast Cells—if
Parasitic worms that have adapted to humans are able to modify and recalibrate almost every facet of their host’s immune system. They employ a wide range of immunosuppressive mechanisms.
This might be a protein on the surface of a liver cell, an important molecule that keeps you alive like insulin, or a structure that is part of a nerve cell, for example. If misguided T and B Cells connect to these self-antigens, your adaptive immune system mounts an immune response against your own body.
your MHC molecules actually need to be physically able to bind to your own self-antigen efficiently. This is mostly genetic, and as everything that is etched into our genetic code, bad luck.
The second thing that needs to happen for an autoimmune disease to develop, is that you need to produce either a T or a B Cell that is actually able to recognize self-antigen and that does not get killed by your own body.
Step one: There are individuals who have a genetic predisposition. (Which is not a required step but it greatly enhances your chances.) Step two: They make B or T Cells that are able to recognize a self-antigen. Step three: An infection provokes the Innate Immune System into activating these faulty B or T Cells.
a popular idea among immunologists is called molecular mimicry. It basically means that the antigens of microorganisms can be similar in shape to the proteins of your cells, your self-antigens.
maybe a virus that has an antigen that is similar to a self-antigen. For example, it could be similar to a common protein that is inside your cells.
In the closest lymph node, your Dendritic Cell may then find a Helper T Cell or a Killer T Cell that can connect extremely well to the antigen of the enemy. And because it is similar to a self-antigen, the T Cell receptor also is pretty OK-ish at connecting to the self-antigen that the antigen is similar to.
anergy, which is a passive and pretty ingenious tactic your immune system deploys to deactivate T Cells that are autoreactive, meaning able to recognize your own cells.
So, as constant background noise when you are not sick or injured, your Innate Immune System uses its free time to low-key fight autoimmune diseases.
It seems like you can draw a direct line from how developed and rich a society is to how much of its population suffers from some kind of allergy or autoimmune disorder.
The number of new cases of type 1 diabetes is ten times higher in Finland than it is in Mexico, and 124 times higher than in Pakistan.
As many as one in ten of all preschool children in Western countries suffer from some form of food allergy while only around two ...
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Today many scientists are quite upset how the Hygiene Hypothesis has permeated popular culture and thinking. Because it leads to “gut feeling”
virtually every infectious disease we know today arose in the last ten thousand years. From cholera, smallpox, measles, influenza, and the common cold to chicken pox.
Surviving the measles does not make you tougher, it just makes your life bad for two weeks. And if your immune system is not in good shape it might also just kill you.
When you are born, your immune system is like a computer. It has hardware and software and is in theory able to do a lot of things. But it doesn’t have a lot of data.
If it does not get enough microbial data and can’t learn enough, the risk rises that it will grow up to be overly aggressive and will later go on to attack harmless substances like peanuts
The rates of asthma and other allergic disorders are four times higher in Hutterites than in the Amish. So it seems growing up in a less-urban environment offers some protection against allergic disorders. Also, it is fair to conclude that a little bit of dirt does not harm you, in fact it might be good for you.
until very recently in human history, people lived in houses made from natural materials like wood, mud, and thatch, all full of microbes that were all too familiar to our immune systems.
Evolution made sure that newborns get plenty of face time with the old and proven microbiome. Both C-sections and the lack of breastfeeding are correlated with a higher rate of immune disorders like allergies.
Fiber is an important power food for a lot of useful and friendly commensal bacteria, and the fact that we just eat less and less of it means that we can’t sustain these little bacteria buddies in the numbers that we might need them.
The transition of our microbial microenvironment and stunted microbiomes was probably a gradual one that happened only in the last century or
Over time the average diversity of the microbiome in developed countries seems to have fallen considerably, especially compared to humans still living a more traditional and rural lifestyle.
wherever humans grow up with more access to microorganisms that are old friends, our immune system should fare much better, and indeed there are a lot of observations that support this notion.
while it doesn’t seem to make a difference if a house is clean or not, it does make a difference if it is surrounded by cows and trees and bushes and if dogs roam freely.
The drug was an artificial antibody that was able to connect to and stimulate the CD28 molecule on T Cells—we already met CD28 before without naming it—one of the signals T Cells need to be activated.
Stress also releases hormones like cortisol that shut down and suppress your immune system,
cancer is when cells in a certain part of your body begin to grow and multiply uncontrollably.
When cancer cells form in solid tissue, like your lungs, muscles, brain, bones, or sexual organs, they form tumors.
“liquid” cancers affect your blood, bone marrow, lymph, and lymphatic system and often start in your bone marrow,
when a mutation switches these oncogenes on again, the corrupted cell can begin to divide and proliferate rapidly, just like when it was trying to create a new human inside a womb.
The second key mutation has to happen in the genes that are responsible for fixing your broken genetic code, appropriately named tumor suppressor genes. These genes produce safeguards and control mechanisms that continuously scan your DNA for mistakes and copying errors and fix them right away.
If cells lose the ability to kill themselves when it is time, when they become unable to fix the mistakes that are naturally amassing in their genetic code, and when they begin to grow without restraint, they become cancerous
cancer cells always come with a certain set of genetic corruptions, which lead to corrupted proteins. Some of your adaptive immune cells have receptors that are able to connect to these proteins.
one of the genius and horrifying methods cancer cells have to protect themselves from the immune system is targeting inhibitor receptors on Killer T Cells and on Natural Killer Cells. Inhibitor receptors inhibit these cells from, well, killing. They are a sort of off switch that deactivates Killer Cells before they can attack a cell and destroy it—which
Cigarette smoke is saturated with over 4,000 different chemicals, many of them with unknown properties and interactions with each other. But we know for sure that nicotine, the magic and vile substance that makes smoking addictive, suppresses your immune system.
it affects your Alveolar Macrophages we met briefly before. They are basically just Macrophages that are more chill and patrol the surface of your lungs to pick up trash and the occasional pathogen.
Given enough time these Macrophages high on nicotine can destroy large amounts of the functional tissue of the lung, creating wounds that turn into scar tissue.
The coronavirus targets a specific and very important receptor called ACE2. This receptor has a few vital jobs in your body, specifically regulating your blood pressure,
the ACE2 receptor also sits on cells in a variety of tissues and organs around your body. Your blood vessels and capillaries, your heart, your gut, and your kidneys. All of them have ACE2.
In many serious COVID-19 cases, a coagulation cascade is triggered that leads to blood clotting,
One of the reasons why some people are able to deal better with the coronavirus than others is the genetic variability and the difference in MHC molecules
