The Four Types of Allergy

The term allergy was coined by a Viennese pediatrician, Claude von Pirquet, in 1906, to explain the sneezing of children exposed to pollen. The clearest translation of its meaning is “altered reactivity,” and it soon became clear that allergy involves excessive and abnormal activation of the immune system.

During the 20th century, scientists identified four types of immune activation that lead to allergic reactions.7 All four types can occur in people with allergic disorders.8 Each type requires that your immune system recognize a specific allergen because of a previous exposure to it. In the first three types, that previous exposure caused your immune system to make antibodies directed against the allergen. The usual function of antibodies, which are proteins made by cells of your immune system, is to create immunity, helping you resist infection; allergy turns this protective effect into a harmful one. The fourth type of allergy, the type that occurs with nickel dermatitis, does not require antibodies to produce its effects.

Type 1 Allergy

Type 1 allergic reactions, the most common form, result from formation of an antibody called IgE (immunoglobulin E). When IgE attaches to an allergen, it stimulates mast cells to release mediators like histamine into your tissues with explosive force. Standard blood tests for allergies look for the presence of IgE antibodies directed against specific allergens. Skin tests for allergies attempt to measure the swelling produced in your skin when IgE antibodies attach to an allergen that’s being injected.

Type 1 is the kind of allergic reaction that occurs with anaphylaxis, eczema, hives, hay fever, and allergic asthma. It has two phases, early and late. Symptoms of the early phase allergic response are caused by the release of mast cell mediators. They can occur within seconds of exposure to an allergen and may last for a few hours. Some mast cell mediators also attract Eos to the inflamed tissues.

Activation of Eos creates the late phase allergic response. The most potent mediators released by Eos are enzymes that damage cells. They’re capable of killing parasites and can inflict the same kind of damage on your own tissues. The late phase reaction may last for days and can cause long-lasting changes to your tissues and your immune system: damaged tissues may heal with scarring, and your immune system may shift so that your lymphocytes further increase their production of IgE antibodies. It’s a dangerous cascade that can allow allergies to spin out of control.

If you suffer from allergic eczema, you can see the difference between the early and late phase responses in your own skin. When you eat a food to which you’re allergic, your skin becomes red, somewhat swollen, and very itchy. Once this early phase reaction subsides, your skin becomes  thickened and scaly, still red and itchy but with less intensity. That’s the late phase response, and if it lasts long enough, your skin does not readily return to normal.

Type 2 and Type 3 Allergy

Type 2 and Type 3 allergy depend upon another class of antibody, called IgG (immunoglobulin G), to amplify the allergic signal. IgG is the main class of antibodies circulating in your blood. IgG is essential for a normal immune response, and its deficiency predisposes people to recurrent or chronic bacterial infections. Type 2 and 3 reactions are the main mechanisms involved in drug allergies and may occur in some people with food allergy, especially when migraine headache, abdominal pain, or arthritis are the allergic symptoms.

Two factors make Type 2 or Type 3 allergy to foods or drugs hard to detect. First, IgE antibodies are not involved, so standard allergy tests, which measure IgE, will not detect this kind of allergy. Second, the onset of the allergic reaction is often delayed, sometimes occurring 24 hours or more after exposure to the triggering allergen. You have to be a really good detective to track down these reactions. The same is true for Type 4 allergy, which is known as delayed hypersensitivity.

Type 4 Allergy

Type 4 allergic reactions do not require antibodies. The triggering allergens directly activate immune cells called helper lymphocytes, which amplify the response themselves, attracting so-called killer lymphocytes to the area where the antigen is found. Killer cells are just as effective as Eos at causing tissue damage.

Type 4 reactions occur in a number of infectious diseases, such as tuberculosis, where they help to control the spread of the infection. They also contribute to the damage that occurs in several autoimmune disorders, including rheumatoid arthritis, Crohn’s disease, type 1 diabetes, multiple sclerosis, and Hashimoto’s thyroiditis.

The most common allergic disorder employing the Type 4 mechanism is poison ivy, an allergic skin rash caused by exposure to oils from plants in the genus Toxicodendron. Allergic contact dermatitis (like Flip’s allergy to nickel, for example) usually involves a Type 4 reaction. For some people, Type 4 reactions may cause asthma. As I describe in Chapter 12, up to 15 percent of asthmatic reactions may occur because of Type 4 allergy. Food allergy may also be caused by Type 4 reactions, especially when the allergic reaction affects the gastrointestinal tract or the skin.

Anaphylaxis: Allergy That Can Kill

The term anaphylaxis was coined in 1901 by the French scientist Charles Richet, who received the Nobel Prize for his research in 1913. Richet coined a new word for what he believed to be a new concept: hypersensitization, or, as he expressed it, “the opposite of a protective response.” With an anaphylactic reaction, your body is flooded with chemicals that cause instantaneous, massive swelling of the affected tissues, dilation of blood vessels, contraction of the smooth muscles that line your airways or intestines, and irritation of nerve endings. If the reaction involves your tongue, throat, or respiratory tract, you may be unable to breathe. If it involves your circulatory system, your blood pressure can drop profoundly, producing anaphylactic shock. Swelling of your face, your lips, your eyes, or any part of your skin, as well as wheezing, abdominal cramps, and diarrhea, are other symptoms that may occur with anaphylaxis.

The usual triggers for anaphylaxis are insect stings, specific foods such as peanuts, or medication such as penicillin. Emergency treatment is essential and starts with an injection of adrenaline, which raises blood pressure, constricts blood vessels and dilates bronchial tubes.

Anyone with a history of anaphylactic reactions should carry a device for rapid self-injection of adrenaline at all times and have an emergency action plan worked out with his or her personal physician.

The incidence of anaphylactic reactions has doubled over the past decade, with an estimated 1,500 fatalities a year in the United States, yet most patients receiving emergency treatment for anaphylaxis at U.S. hospitals do not receive an adrenaline auto-injector or an allergist referral when discharged, a missed opportunity for preventing further reactions.

Studies in many different countries have all reached the same conclusion: people prone to anaphylaxis are not adequately armed with adrenaline. As severe as it is, life-threatening anaphylaxis is still underdiagnosed, underreported, and undertreated.

Peanut Allergy

Peanut allergy is one prevalent cause of anaphylaxis. Peanuts contain at least 12 allergenic proteins, two of which can cause anaphylaxis in sensitive individuals. A telephone survey of more than 4,000 U.S. households in 1997 concluded that peanut or tree nut allergies affected 1.1 percent of those surveyed (which translates to about three million people in the U.S. population). A follow-up study five years later found a doubling of peanut allergy among children.14 By 2007 the prevalence of peanut allergy among schoolchildren in the United States had tripled, and researchers were using the term epidemic to describe the increase. A British study documented a tripling in the rate of allergic skin-test reactivity to peanut extract among schoolchildren during the 1990s and a doubling of clinical allergic reactions to peanuts.

The reasons for the increase in peanut allergy are not clear. Most children with peanut allergy get sick immediately on their first known exposure to peanuts. For this to happen, the child must already have been exposed to peanuts, so that his immune system became sensitized to peanut allergens. Researchers at Imperial College London attempted to identify factors that separated children with  proven peanut allergy from children with other allergies or no allergies. The most significant  difference was that children who developed peanut allergy had been rubbed with skin care products containing peanut oil (arachis oil) twice as often as children who did not develop peanut allergy.

Peanut oil is a common component of skin care and infant care products in the United States as well as the United Kingdom. The list of commonly used topical preparations that contain arachis oil includes Cerumol (for removing earwax), Siopel barrier cream, zinc and castor oil ointment, calamine oily lotion, Dermovate (a potent topical steroid cream used for difficult eczema), and Naseptin cream.

The British researchers also found that peanut allergy was more likely to occur if other family members ate peanuts. Their theory is that exposure to peanut allergens through the skin is the main risk factor for peanut allergy. This theory might explain why children with eczema are at increased risk for developing anaphylaxis from peanuts. The inflamed and broken skin of eczema allows increased absorption of peanut antigens through the skin.

There is at present no specific treatment that can reverse peanut allergy.

Source: The Allergy Solution: Unlock the Surprising, Hidden Truth about Why You Are Sick and How to Get Well Paperback by Leo Galland M.D. and‎ Jonathan Galland J.D. (Aug 2017)

Allergies on the Brain

There’s no topic in the field of allergy as controversial among doctors as the notion that allergic reactions can have a direct impact on your brain. I’m amazed at the controversy, because I’ve seen the effects of brain allergy in so many of my patients, children and adults alike. The reactions have ranged from spaciness and lack of concentration to depression, anxiety, and mental confusion. Patients of mine with brain allergy have often been previously diagnosed with attention deficit disorder, hyperactivity, autism, and bipolar disorder. For these patients, eliminating the allergic trigger can often help relieve the mental disorder.

Research on Brain Allergy

The earliest published report on brain allergies appeared in the Southern Medical Journal in 1943. Dr. Hal Davison, an Atlanta physician, made the following observations:

For a long time it has been noted that symptoms of bizarre and unusual cerebral disturbances occur   in allergic patients. . . . Later it was observed that when the allergic symptoms improved, the cerebral symptoms improved also. . . . Further observations and experiments showed that at times the cerebral symptoms could be produced at will, by feeding patients certain foods. It was also observed in rarer instances, that ingestion of a drug, inhalation of powdered substances or even odors would produce these symptoms.40

Davison then described 87 patients seen in his allergy practice over an eight-year period with symptoms that included blackouts, insomnia, confusion, and changes in personality, all clearly provoked by specific foods or inhalants. As is always the case with allergy, different triggers affected different people. One of the patients, a lawyer, had a progression of symptoms that would start with a headache, followed by itching and hives, then blurred vision, drowsiness, and impaired speech, ending with loss of consciousness. The food triggers were eggs, crab, oysters, and strawberries. Avoiding these foods completely resolved his symptoms.

Medical journals today rarely publish the kind of detailed clinical observations made by Dr. Davison, although they are real and reproducible. In 1985 I spent a day with Professor Roy John, founder of New York University’s Brain Research Laboratory and a pioneer in the creation of electronic maps of brain activity. He told me that when patients were connected to his brain mapping device and then injected with extracts of foods, molds, or chemicals to which they were allergic, the injections produced dramatic changes in brain electrical activity, accompanied by the symptoms for which the patients had initially sought care.

Later in this book, in the chapter on nasal and sinus allergies, I’ll describe experiments done in Europe in which pollen exposure provoked impairment of brain function comparable to the effects of sedative drugs or alcohol.

Allergy and ADHD

Important scientific research on food allergy and the brain comes from England. Dr. Josef Egger, a neurologist, found that food allergy could lead to ADHD.

Dr. Egger and his colleagues identified 40 children with severe ADHD whose behavior improved when they avoided specific foods.41 Half the children then underwent an allergy desensitization procedure designed by a colleague of mine, Dr. Len McEwen. They received injections of low doses of food allergens mixed with an enzyme that stimulates an immune response. The other half received injections of the carrier solution without the allergens; this was the placebo control. At the end of six months, 80 percent of the children receiving the allergen injections were no longer reactive to the foods that had caused behavioral changes. Only 20 percent of the children receiving placebo had become nonreactive to the foods they’d been avoiding. This clearly indicates that allergy—a reaction in which your immune system amplifies the response to a trigger—is an important mechanism of food-induced ADHD. Egger’s study was published in The Lancet, which is the oldest medical journal in the world and the leading medical journal in the United Kingdom. If you experience neurologic or psychiatric symptoms that you believe may be provoked by a dietary or environmental exposure, know that science is on your side. Find a doctor who respects your observations—and who understands that allergy comes in more guises than ever in our rapidly changing world.

Conclusion

In this chapter, I revealed the many and surprising ways allergy can impact health. Julia’s case showed us how a hidden allergy, in her case an allergy to sulfites found in food, can lead to unexplained joint pain, stomach pain, fatigue, and difficulty with mental focus.

For Cora, the attorney, an allergy to nightshade plants (tomatoes, peppers, and potatoes) turned out to be the surprising cause of her mouth sores, which healed when she avoided eating these foods. A mysterious case of hives was a real curveball for Bruce, the professional baseball player, until we discovered that the yeast in beer and wine was the cause.

These cases illustrate the Four Game-Changing Truths about Allergies that I believe can transform how we approach health. That is why it is so important that you bring this book with you to see your doctor, to share this information with him or her. Ultimately, it is for your doctor to evaluate and decide how the ideas in this book may inform your journey of healing.

Source: The Allergy Solution: Unlock the Surprising, Hidden Truth about Why You Are Sick and How to Get Well Paperback by Leo Galland M.D. and‎ Jonathan Galland J.D. (Aug 2017)