Decoding the mystery of allergies and anaphylaxis: What has knocked down the body in just a few minutes?

One day of waking up, the weather changes making you rash and rash full of people. Or more seriously, you may feel your heart beat faster, have an asthma attack and have trouble breathing after being exposed to some strange agent in the air, cat hair or pollen, for example.

These are common manifestations of allergies . It's hard to understand why the weather and a cat's hair can make your body itch and swell. In special cases, allergies also cause anaphylaxis and murder.

It is dangerous and cannot be underestimated. But what causes the allergy to cause anaphylaxis? It is still a mystery to scientists. They are taking this very seriously and carefully.

Recently, a mouse study published in Science magazine revealed for the first time what happens inside the body, after exposure to very small amounts of allergens. Find out why allergies can knock down your body in minutes?

Expression of allergy.

Dendritic cells: A center of anaphylactic shock

We know that allergy is a consequence of the confusion of the immune system , when it misidentifies a harmless substance to be harmful. After that, hypersensitive immune reactions will appear.

• If allergens come from air, such as pollen, animal hair, common symptoms are sneezing, runny nose, itching, red eyes, coughing, wheezing .
• If allergens are food , such as some people are allergic to peanuts, seafood, and some antibiotics, the common reaction is abdominal pain, fullness, vomiting, rash, itching .

But the most dangerous consequence that allergies are likely to cause is anaphylaxis. Anaphylaxis affects many organs in the body, from the respiratory system, to the digestive system to the circulatory system. Within minutes after exposure to allergens, anaphylactic shock can cause edema, rapid heartbeat, bronchospasm, hypoglycemia until coma and death.

Each year in the United States there are more than 800 deaths from anaphylaxis with agents such as insect venom, antibiotics, rubber plastics and food .

Previously, scientists knew a type of immune cell called mast cells , playing a central role in anaphylactic shock. When an allergen is detected, these cells release inflammatory molecules such as histamine and produce an inflammatory reaction as a defense mechanism.

But so far, they still do not know why the information about the presence of the allergen can be transmitted very quickly between mast cells, to cause a rapid shock response. so.

In the new study in mice, scientists finally grasped clues from a type of cell called dendritic cells .

"The main finding here is that dendritic cells, the main factors in the development of allergies, also play a direct role in activating anaphylactic shock , " the immunologist and the main author of Soman N. Abraham's study from Duke University said.

To find out, Abraham and his colleagues reduced the number of each type of immune cell in experimental mice. They then injected their bodies with anaphylaxis.

The results showed that mice could not just use mast cells to produce an allergic reaction. Because when they reduced dendritic cells, mice did not have anaphylaxis.

Dendritic cells are the center of anaphylaxis.

Beat the body in just a few minutes

To investigate further, scientists used dual photon microscopes to observe the activity of dendritic cells. They are called dendritic cells because a branch of them has long tendrils that grow out to probe into other cells.

When dendritic cells cling to the outer surface of blood vessels, they use these branches to penetrate the cell wall, searching for invading substances. If an allergen is detected, dendritic cells will transmit this information to all surrounding mast cells - and how they do this is strange.

Normally, when dendritic cells detect antigens (molecules that stimulate the body's immune response), they will receive them, process and bring information about antigen to the cell surface and transmit. It reaches the T cells of the immune system, activating a defense response.

But with allergens, dendritic cells pull it out of the blood vessels, then wrap it in a small bubble called microvesicles born from the surface itself.

"In addition to the previously known capacity of receiving, processing and presenting antigens to immune cells, dendritic cells are still actively distributing antigens that they have obtained to the cells. immune cells around, " explained immunologist Hae Woong Choi from Duke University.

It is this delivery method that helps dendritic cells spread information much faster and reach a large number of immune cells. When immune cells receive microvesicles, mast cells are strongly activated, secreting more histamines and other inflammatory mediators into the blood, triggering anaphylactic shock.

Anaphylaxis causes more than 800 deaths in the United States each year.

"Although it is harmful to identify allergens, this function may be necessary when fighting against disease," Abraham said. "Maybe these dendritic cells are designed to detect parasites, viruses or bacteria floating in the blood."

Currently, we cannot know the mechanism of causing anaphylaxis that the dendritic cells used on mice are similar to humans. But if it's like, scientists will have a way to create a way to prevent this danger.

Scientists will have to calculate to preserve the useful effect of dendritic cells, while limiting their confusion."We need to learn all the possibilities to activate dendritic cells before planning to turn them off or hinder their activity , " Abraham said.

Anaphylaxis is an extremely serious allergic reaction to the victim's life. It can happen within a few seconds or minutes of exposure to something allergic, such as venom from bee venom, peanuts . Anaphylaxis is an extremely dangerous allergic reaction. , can cause death.