What is an allergy - a disease or a protective reaction of the body, worked out over the centuries? Scientists have opinions differ, and probably that is why a drug that would once and for all rid us of the unpleasant symptoms have not yet been found. We invite you to an article with the interesting facts and studies that shed light on this issue.
I have never had a pronounced congenital allergy to something. One time in six years I sprinkled because I stuffed strawberries - that's all I can talk about their allergies. Some of my friends allergic reactions to certain flowering plants (poplar fluff) appeared at a mature age, and some are allergic to stop worrying after 13 years. Why is this happening, how to protect yourself from this, is it possible to avoid it and what to do if it's hereditary?
Allergy (ancient Greek. Ἄλλος - other, different, stranger + ἔργον - action) - hypersensitivity of the immune system with repeated allergen exposure to a previously sensitized with this allergen body.
Scientists still have not come to a common denominator and can not say exactly where does the allergy, but the number of people suffering from some form of it, is growing. Among allergen latex, gold, pollen (especially ragweed, pigweed and common cockle), penicillin, insect venom, peanuts, papaya, jellyfish stings, perfume, eggs, mites feces, pecans, salmon, beef and nickel.
One has only to these substances start a chain reaction as your body sends its reply to a fairly wide range of reactions - from annoying rashes to death. Rash, swollen lips may start shivering, it lays nose and burns to the eyes. Food allergies can cause vomiting or diarrhea. A very unlucky minority allergy can result in a potentially fatal reaction known as anaphylactic shock.
Medication is there, but none of them can get rid of allergies. Antihistamines clean symptoms but cause drowsiness and other not so pleasant side effects. There are drugs that actually save lives, but they need to take a very long time, and some types of allergies are treated only complex methods, that is one embodiment of the drug is clearly not manage.
Scientists will be able to find a medicine that once and for all rid us of allergies, only if they understand the underlying causes of the disease. But while they have deciphered the process only partially. In addition, there is a global issue:
Why do we suffer from allergies?
It is this fundamental question concerned Ruslan Medzhitova, a scientist who for the past 20 years has made several fundamental discoveries related to the immune system, and has received several serious prizes, including 4 million euros from the Else Kröner Fresenius Award.
Currently Medzhitov studies question that can make a revolution in immunology: Why do we suffer from allergies? The exact answer to this question yet no one has. There is a theory according to which the allergy - a reaction to the venom of parasitic worms living in our body. In the more developed countries and almost sterile, which is rare, is not accustomed to such immune system provides sharper, a massive strike in response. That is the child of a developing country, which lives almost in a hut and quietly eating unwashed fruits, may not even know what allergies, while children whose parents permanently wipe all sanitayzerami and two times a day wash the floors in the apartment are a whole bunch of "That we can not! We are allergic to it! ".
Medzhitov believes that it is wrong and that allergies - it is not just a biological error.
Allergy - a protection against harmful chemicals. Protection that helped our ancestors millions of years and helps us so far.
He admits that his theory is controversial, but he is confident that history will prove him right.
The healers of the ancient world knew a lot about the allergy. Three thousand years ago, Chinese doctors have described "allergic plant", which caused the fall of a runny nose. There is also evidence that the Egyptian Pharaoh Menes died from a wasp sting in 2641 BC, and 2.5 thousand years ago, the Roman philosopher Lucretius wrote: "What is one thing - food, for another - the poison."
And only a little over 100 years ago, scientists realized that these different symptoms can be a hydra heads. Researchers have discovered that many diseases are caused by bacteria and pathogens and our immune system is fighting with these violators - an army of cells that can release deadly chemicals and clearly targeted antibodies.
It was also found that, besides the protection, the immune system can cause harm. At the beginning of XX century, French scientists Charles Richet (Charles Richet) and Paul Porter (Paul Portier) studied the effect of toxins in the body. They injected a small dose of poison sea anemones dogs and then waited a few more weeks before you enter the next portion. As a result, the dog was prepared and anaphylaxis die. Instead, to protect animals, the immune system makes them more susceptible to this poison.
Other researchers have noticed that some medications cause rashes and other symptoms. And this sensitivity is developed on the rise - the reaction, reverse protection against infectious diseases, which provide the body antibodies. Austrian physician Clemens von Pirke (Clemens von Pirquet) studied whether a body is to change the body's reaction to incoming material. For a description of this work, he coined the word "allergy", combining the Greek words alos (other) and ergon (work).
In the following decades, scientists have discovered that the molecular steps of these reactions were surprisingly similar. The process is triggered when the allergen proved to be on the surface of the body - the skin, the eyes, nasal passages, throat, respiratory tract or intestines. These surfaces are filled with immune cells, which act as border guards. When the "border guard" is faced with an allergen, it absorbs and destroys intruders, and then completes the surface fragments of matter. Then the cell locates some lymphoid tissues, and the fragments are transmitted to other immune cells that produce the specific antibody known as immunoglobulin E, or IgE.
These antibodies will cause a response, if the newly run into allergen. The reaction starts immediately after the antibody activates components of the immune system - the mast cells, which cause a flurry of chemicals. Some of these substances can catch the nerves, causing itching and coughing. Sometimes it begins producing mucus, and contacting those substances airways may cause breathing problems.
This picture was drawn by scientists during the last century, but it only responds to the question "How?", But does not explain why we suffer from allergies. This is surprising, since the answer to this question is clear enough for most parts of the immune system. Our ancestors faced with the impact of pathogenic organisms, and natural selection has left mutations that helped them to reflect these attacks. And these mutations accumulate until now in order that we may rebuff.
See how natural selection could create allergy was the most difficult. Severe allergic reaction to the most innocuous things hardly included in the survival of our ancestors. Also, allergies can be quite strange election. Not all people are prone to allergies, and only a few substances are allergens. Sometimes people have allergic to quite adult, and sometimes children's allergies disappear without a trace (we say "evolved"). For decades, no one really could not understand why do we need IgE. He showed no special abilities that could stop a virus or bacterium. Rather, it seems that we have evolved to a special type of antibodies gives us great trouble.
The first clue came to us in 1964. Parasitology Bridget Ogilvie (Bridget Ogilvie) to investigate how the immune system responds to parasitic worms. She noticed that the rats infected with worms, began to churn out what later became known as IgE. Subsequent studies showed that the antibodies gave a signal to the immune system to attack and destroy the worms.
Parasitic worms pose a serious threat not only to the rats, but also to humans. For example, the nematode can delay the blood from the intestine. Liver fluke can damage the liver and cause cancer and tapeworms can cause cysts in the brain. More than 20% of people carry these parasites in itself, and most of them live in low-income countries.
In the 1980s, a group of scientists vigorously advocated the link between these parasites and allergies. Perhaps our ancestors developed the ability of an organism to recognize proteins on the surface of worms and responsible production of antibodies IgE. Antibodies embedded cells of the immune system in the skin and intestine, quickly reacted as soon as any of these parasites trying to penetrate into the body. The body has about an hour to ensure that the chances to bring this parasite survival to zero, according to David Dunn (David Dunne), parasitologist from the University of Cambridge.
According to the theory of parasites, helminths protein in its shape is similar to other molecules to which your body is faced in everyday life. As a result, if we are faced with harmless substances, the shape of which is similar to the shape of the protein parasites, our body raises the alarm and protection idles. Allergies in this case is simply an unpleasant side effect.
During the internship Medzhitov studied the theory of worms, but 10 years later he started to appear questionable. According to him, this theory did not make sense, so he started developing his own.
Basically he was thinking about how our bodies perceive the world around us. We can distinguish photons samples using our model eye and vibration air with our ears.
According to the theory Medzhitova, the immune system - is another pattern recognition system that recognizes the molecular signatures instead of light and sound.
Confirmation of the theory Medzhitov found in Charles Janeway (Charles Janeway), immunologist at Yale University (1989).
Meanwhile, Janeway believed that antibodies have one big drawback: it takes a few days for the immune system has developed its response to the aggressive actions of the new invader. He suggested that the immune system may have another line of defense that works faster. Perhaps she can use pattern recognition system to quickly detect bacteria and viruses, and quickly begin to eliminate the problem.
After an appeal to the Janeway Medzhitova scientists began work on the problem together. Soon they discovered a new class of sensors on the surface of certain types of immune cells. Faced with the invaders, the sensor covers the offender and include chemical alarm that helps other immune cells find and kill pathogens. It was a quick and accurate way to detect and eliminate bacterial invaders.
So they opened the new receptor, now known as Toll-like receptors, which showed a new dimension in the immune defense and which was declared a fundamental principle of immunology. It would also help to solve a medical problem.
Infections sometimes lead to catastrophic inflammation throughout the body - sepsis. Only in the United States alone it is a blow to millions of people each year. Half of them die. For many years, scientists believed that bacterial toxins can lead to malfunction of the immune system, but sepsis - is just an overreaction of the immune defense against bacteria and other invaders. Instead of acting locally, it includes a line of defense around the body. Septic shock - the result of the fact that these defense mechanisms are activated much more strongly than it actually is the situation requires. The result - death.
Despite the fact that initially studied science Medzhitov not to treat people, he made the discovery allow doctors to take a new look at the mechanisms that trigger sepsis, and thus find an appropriate treatment, which will be aimed at addressing the real cause of the disease - overreaction toll-like receptor.
Medzhitov went on. Once in the immune system have special receptors for bacteria and other intruders, possibly it has and still unknown to us, and receptors for other enemies? That's when he began to think about the parasitic worms, IgE and allergy. And when he thought about it, something did not add up.
Indeed, the immune system triggers the production of IgE, when faced with parasitic worms. But some studies show that IgE is actually not the main weapon against this problem. Scientists have observed the mice that can produce IgE, but the animals still could build protection against parasitic worms. Medzhitov rather skeptical of the idea that the allergens are proteins pretended parasites. A large number of allergens such as nickel or penicillin has no possible analogues in molecular biology of the parasite.
The more Medzhitov thought of allergens, the less important it seemed their structure. Perhaps what connects them, not their structure, and their actions?
We know that very often allergens lead to physical damage. They tear open the cells, irritate the membrane proteins break apart. Perhaps allergens cause such great harm, we need to defend them?
If you think about all of the major allergy symptoms - stuffy red nose, tears, sneezing, coughing, itching, diarrhea and vomiting - all these phenomena have a single common denominator. They are like an explosion! Allergy - a strategy to get rid of the body from allergens!
It turned out that this idea has long floats on the surface of different theories, but each time it stoked again. Even in 1991, evolutionary biologist Margie Profiles (Margie Profet) claimed that allergy struggled with toxins. But immunologists rejected this idea, perhaps because the prof was an outsider.
Medzhitov with two of his disciples Palm Noah (Noah Palm) and Rachel Rosenstein (Rachel Rosenstein) published his theory in Nature in 2012. Then he started testing it. First he checked the connection between the injuries and allergies. He and his colleagues introduced the mouse PLA2, the allergen is found in bee venom (he breaks the cell membranes). As Medzhitov predicted, the immune system does not react specifically to PLA2. Only when PLA2 damaged cells open, the body began production of IgE.
Another assumption Medzhitova stated that these antibodies would protect mice, and not just make them sick. In order to check this, he and his colleagues did a second injection of PLA2, but this time the dose was much higher. And if the first dose response in the animals was practically absent, after a second body temperature rose sharply, until death. But some of the mice is not quite understandable reasons lined up a certain allergic reaction, and their body to remember and reduce the impact of PLA2.
At the other end of the country to another scientist was doing an experiment that as a result of further confirm the theory Medzhitova. Stephen Galli (Stephen Galli), head of the department of pathology at Stanford Medical University, spent years studying mast cells, mysterious immune cells that can kill people as a result of an allergic reaction. He suggested that in fact these mast cells can help your body. For example, in 2006 he and his colleagues found that mast cells destroy toxins found in snake venom. This discovery led Galli think the same thing, what they think and Medzhitov - that allergies can actually be protected.
Gallo and his colleagues conducted the same experiments with mice and bee venom. And when they entered into mice that had never experienced this kind of venom antibody IgE, it turned out that their bodies get the same protection from a potentially fatal dose of poison, as well as the body of mice exposed to this toxin.
Until now, despite all the experiments, unanswered many questions remain. Exactly how the damage caused by bee venom, leading to a protective response IgE and IgE how protected mice? These are the questions that are currently running Medzhitov and his team. In their opinion, the main problem - is the fat cells and the mechanism of their work. Jamie Cullen (Jaime Cullen) has studied how IgE antibodies fixed mast cells, and are doing so that they are sensitive, or (in some cases) hypersensitive to allergens.