An allergic reaction defined in the lay sense is a damaging immune response to an environmental allergen.
In technical terms an allergic reaction is called a "Hypersensitivity". There are four major categories of hypersensitivity. They are called Type I, II III and IV. In each of these 4 types of hypersensitivity, the cells involved, the chemicals that are made and released, the mechanism of the reaction and how long it takes the tissue damage to be visible, distinguish one type from another.
There are links at the end of this page to learn more about all four types
Hypersensitivity, by definition, is an immune response that produces tissue injury upon subsequent exposure to an agent that is not intrinsically harmful.
There are some keys to this definition. First of all, it is the second exposure and every exposure there after that provokes this response.
The first exposure to a substance that causes a hypersensitivity causes the immune system to make some special antibodies. This takes some time. Once those special antibodies are made, they assume a "sit and wait" position on special cells in your gums or other tissue and are ready to launch an almost instantaneous attack the next time the substance is introduced. These antibodies are also floating around in your blood stream. As your body uses up antibodies, it sends chemical messengers to your bone marrow to make more. You are constantly armed against the chemical substance. This reaction does not have to be as obvious or as severe as asthma. These antibodies are chemical compounds in a class called immunoglobulins.
Secondly, the definition says that the agent is not intrinsically harmful. Pollen is not harmful, meaning it is not a biological pathogenic threat that can reproduce itself inside your body. Chemical substances are in this same category. Your body thinks that the chemical substance that you are introducing is a bacteria, virus, parasite, bacterial toxin etc. and attacks it in order to destroy it so that it cannot infect you. The recognition of the microorganisms that cause diseases occurs because they have chemicals on their surface. Your body sees the chemical and notes that it is foreign. The body then destroys the foreign invader. You must be allergic to a chemical substance for your body to attack it. That means that you are able to recognize specific chemicals or specific chemical ingredients in products and foods as foreign invaders. Allergies of this type are extremely common. Allergies are completely individualized and you can be allergic to anything.
Finally, the reaction does tissue injury.
When you put a chemical compound in your mouth and you are allergic to it, your immune system views the molecules of that substance as if it were a nasty bacteria or virus. It attacks it, right on your gum tissue, with the intent of destroying it. In the process of destroying it, it destroys some of your own tissue by releasing many chemicals. It is the release of these chemicals that cause tissue damage and inflammation. There are three things that factor into the amount of tissue damage done with each introduction of the chemical compound:
Your body has no foreknowledge that there will be ongoing introductions of the substance. Each exposure is treated as if it was an isolated event. Each exposure does more tissue damage. The body does not stop attacking when it is doing more damage than it can keep up with in repair. Eventually the tissue damage that you do exceeds your capacity to heal and your gums become chronically red, inflamed, irritated and receded. The gums recede due to bone loss. The allergic response is responsible for the bone loss.
This is also called a PK reaction or a wheal and flare reaction. The wheal part corresponds to hives and the flare part corresponds to a stinging or burning sensation and a redenning of the area. On the skin, this reaction causes a rash, burns or both. This reaction does not always produce hives and does not always produce a burn. It can produce the wheal without the flare and the flare without the wheals. This reaction on the skin frequently causes itching.
This is the same reaction that causes anaphylactic shock in people. When anaphylactic shock happens on a systemic level and the reaction is severe, it can cause death. It is the same reaction as asthma. In the case of asthma, the inflammatory reaction takes place inside the lungs. When this reaction occurs on a specific organ or tissue such as the gums, lungs or skin, it is called "local anaphylaxis". The only difference between local and systemic anaphylaxis is that local anaphylaxis occurs on a particular tissue or organ. The reaction can range from mild to severe. Some people have only mild allergies to dust, pollen and mold. It can cause an itchy scalp after using shampoo, labored breathing in the presence of fragrances, skin reactions to skin products and cleaners, hives from food or food additives and sneezing from exposure to animals. The symptoms are greatly varied and depend on the substance and how the individual reacts to it. The local reaction can be visible or evident on the exposed tissues.
The mechanism of a Type I reaction involves two types of cells, basophils and their tissue equivalents called mast cells. The antibody classe is called IgE. The IgE antibody specific to a substance binds to basophils and mast cells where it waits for the substance to show up. There are hundreds of thousands of these cell-antibody complexes waiting for the substance. When the substance is introduced, it binds to the specific IgE antibody and the complex causes the cell to release chemical substances that have destructive properties. One of these substances is histamine. You can feel a histamine release on the skin or gums, it causes a burning or stinging sensation. This is what makes an allergy to something like mouthwash difficult to distinguish because many mouthwashes sting upon exposure. You really have no way of knowing how much it stings you vs. how much it stings someone that is not allergic to it. The stinging or burning sensation occurs immediately or anytime within about 20 minutes. The inflammation is controlled by chemical substances called leukotrines and prostaglandins. Leukotrines are released by mast cells and basophils. T cells are additional immune cells that arrive on the scene to assist the reaction and make different leukotrines. Antihistamines can block the binding of IgE to the mast cell and help prevent the release of the histamine. Aspirin and Ibuprofen are NSAIDs or non steriodal anti inflammatory drugs. These drugs can block the action of prostaglandins that cause inflammation. The leukotrines are powerful chemical messengers that regulate both the pro and anti inflammatory response. Cytokines and interleukins are also released and induce special cells on the mandibular bone called osteoclasts to break down bone.
The histamine release causes your capillaries to become very permeable. This part of the reaction causes a reddening of the area. This increased permeability allows the immune cells in your blood stream to enter your tissues, such as macrophages and neutrophils. Macrophages and neutrophils are not selective. These cells are not programmed to attack a specific substance but rather will destroy any foreign invader they encounter. These cells will release more chemical compounds in the process of destroying the invader that they capture. Monocytes which become macrophages will release more leukotrines and prostaglandins.
Chemical messengers and chemical destroyers are released as part of the response. Some of these chemical messengers go to your bone marrow to let your bone marrow know that an invader has been encountered and more immune cells will be needed. The attack on the invader does tissue damage. Chemical substances are released to destroy or even dissolve the invader. Your own cells are destroyed and damaged in the process. Enzymes are released that breakdown protein or your own tissue. In addition to histamine, seratonin is also released. Both of these compounds cause smooth muscle contraction. A Type I reaction can have manifestations in seconds to several minutes.
The result is that your gums will be inflamed, red, irritated and damaged. It is almost equivalent to having thousands of little cuts in your gum tissue along with the associated inflammation that occurs with any single tissue injury.
Pus is made from white blood cells or immune cells. When the histamine release occurs, the capillaries get more permeable so that the fighting cells in your blood can get out of the blood stream and into the tissue. Once they are in the tissue, they encapsulate the foreign invader molecule and release chemicals to dissolve it. When you press on your gums, if you get pus, this is your white blood cells that consumed the invader molecules. It is also non selective white blood cells that are cleaning up the cellular debris left behind by the tissue damage done by the allergic reaction. Pus is mostly composed of cells of your immune system.
The poison ivy reaction is called a Type IV reaction. In this reaction type, you may not see the signs of a reaction for up to 3 days after the exposure. All of the visible signs of poison ivy are due to your own immune system doing damage to your own tissues. There is nothing in poison ivy that causes it to replicate and do tissue damage. There is nothing in poison ivy that can directly kill or injure your tissue. The chemical compound in poison ivy binds to your own cells, because your own unique tissue type allows that to happen. Your immune system destroys your own cells because your own cells no longer look like your normal tissue. Any chemical compound that your body allows to bind to your own cells can cause this reaction. It can take place anywhere in your body because you have different tissues throughout your body. This reaction type is also called delayed type hypersensitivity because it takes a long time to see the reaction. It is also called contact dermatitis. This reaction takes longer to be visible because it depends entirely on cells and not on antibody. The cells responsible for initiating the reaction are called T cells. Specific T cells are made to attack specific invaders. The skin reaction produced by a T cell mediated process and a Type I, IgE mediated process may be indistinguishable by visual inspection. They both induce the release of histamine and this is why poison ivy reactions itch. Topical Benadryl is an antihistamine designed to control the itch. T cell mediated reactions can also cause diabetes mellitus, rheumatiod arthritis and multiple sclerosis which are considered autoimmune diseases. The visible symptoms of a T cell mediated reaction take longer to appear because reactions mediated entirely by cells are slower than those that are mediated by antibodies.
A Type III reaction is generally slower than a Type I reaction. Type III reactions sometimes require more substance to provoke this reaction and you may appear to be mildly sensitive to a substance. The reaction takes longer to show up than in a Type I Hypersensitivity. This reaction will generally manifest itself anywhere from 4 to 12 hours after the substance is introduced, but it can actually show up days later. This reaction can be responsible for many auto immune disorders. When the immune system antibody combines with the substance, the resulting complex consisting of those two items is carried by the blood stream and can be deposited on a variety of tissues. Where it is deposited, it causes some special cells to release their destructive chemicals. These chemicals do tissue damage. Common places that the complex is deposited are blood vessels, the skin, joints and kidneys. This class of reactions is known as Immune Complex Disorders. Among the diagnosis of this condition are: Rheumatoid Arthritis (RA) , Sjogren's Syndrome (SS) (not enough saliva, dry eyes), Systemic Lupus Erythematosus (SLE), Progressive Systemic Sclerosis (PSS), Mixed Connective Tissue Disease (MCTD). This reaction manifests itself hours to days after the offending agent is introduced. This class of reaction activates a destructive system known as complement. The antibody-antigen-complement complex attracts basophils and mast cells which release histamine and leukotrines. The IgG class of antibodies is responsible for mediating this reaction. This reaction has much in common with Type I. T cells arrive on the scene and are responsible for the cytokine production and chronic inflammation. They recruit macrophages which do more tissue damage. It shares attributes of a Type IV hypersensitivity.
A Type II reaction involves any substance that can adsorb or attach to cell membranes. Adsorb means it can get into the cell membrane but may not be absorbed by the cell. Your immune system recognizes your own cells with this foreign substance integrated as a foreign invader and destroys them. This mechanism is responsible for many autoimmune or immune mediated diseases. This mechanism involves immune system antibody and this is a distinction from Type IV. Common places that this mechanism occurs is on the skin or endocrine glands. Endocrine glands are tissues that secrete hormones directly into the blood stream, like your thyroid. This reaction manifests itself in hours to a day after the offending agent is introduced. The antibody classes that mediate this response are the IgG and IgM classes. The complement sequence is induced and contributes to the tissue damage.
The attack on pathogens, such as bacteria is taking place 24 hours a day, 7 days a week unless the individual is immune compromised. There are two mechanisms of defense which are classified as humoral and cellular. Humoral defenses use the same antibodies that are involved in any of the hypersensitivity responses. The classes of antibodies that are involved in your normal defenses against foreign invaders are IgA, IgE, IgM, IgG and IgD. Antibodies are specific to a particular substance. The substance may be a particular toxin that the bacteria makes that the antibody neutralizes. The substance can be a part of the bacteria itself that the antibody can attach to and render the bacteria motionless or unable to function properly. The cellular response includes the same cells mentioned above that are not selective and will attack anything that they encounter. T cells are selective or specific to a particular substance. The inflammatory response provoked as a result of a constant attack on bacteria is always present in small way and is virtually continuous. This attack is taking place on all of the tissue throughout your body, constantly, and keeps bacterial colonies and their toxins under control. IgA is the predominant antibody type in bodily secretions. It is found in tears, skin secretions, and the saliva. Gum tissues have both selective and non selective cells as well as the humoral defenses present continually to continually fight bacterial infections and their harmful secretions. Bacteria are microscopic. If you rinsed your mouth twice a day with the same amount of bacteria as you use mouthwash or toothpaste, you will likely get your tissues into a chronically inflammed state from all the tissue damage done by the immune response against the foreign invader.
A chemical irritant or chemical poison can do tissue damage and cause subsequent inflammation. Chemical irritants and poisons kill the cells of your tissue. Even if they do not do this on contact, they start the process. Your immune system then has to clean up all the dead cells and debris. The non selective cells of your immune system clean up this debris. Your immune system and other cells release chemicals in response to the sudden tissue damage. This causes the same signs of inflammation. If your tissue type makes you particularly sensitive to a chemical irritant, then you are going to do a lot more damage, much more quickly than someone that is not.
Each of the four reaction categories may have similar or overlapping manifestations and visual inspection is sometimes inadequate to determine the exact immune response. Determination of the exact immune response is extremely important especially when medications are used to mitigate its effects. The response has an effect on many bioregulatory mechanisms. The wrong medication taken to alleviate symptoms can result in interferring with many bioregulatory mechanims in a negative manner. It is important to get an accurate diagnosis before attempting to treat any inflammation. Masking or effecting the inflammation does not mean the reaction itself is blocked. A physician will assess all of the symptoms, take into account medical history and knowledge of the four immune categories before prescribing medication to subdue the reaction. The physician may refer the patient to an immunologist or a dermatologist to gain more information. An immunologist or a dermatologist may do scratch or patch testing and biopsy the reaction which is the only way to accurately determine which immune players are involved in it. In order to do any testing, the individual must be medication free for a specified period of time depending on the medication. It is better to figure out what is causing the reaction and terminate exposure to it.
Allergies and immunology is a very complex topic. Unfortunately, there was no web site found that does not use some technical terminology. An immunologist or allergist requires 2 additional years of medical education after they are a MD to specialize in this field. The following web site describes allergies and "local anaphylaxis". This is one type of reaction that you can be experiencing on your oral tissues. You may also be damaging your oral tissues by any one or more of the four mechanisms listed. You may be damaging much more than just your oral tissues and not realize it yet. You can react to any chemical substance according to one or more of the four mechanisms.
A definition of allergies. Local Anaphylaxis is discussed shortly after the introduction of the four classes of immune responses.
allergies and chronic Inflammation:
To read more about hypersensitivity in the Journals, this well organized web site from CliniWeb can direct you to various topics of interest:
A description of hypersensitivity using technical terminology:
Many symptoms of allergies:
Piece together the following for a laymans presentation and apply the same principles to your oral tissues:
From the American Medical Association, an overview on hypersensitivities:
Since we are mainly concerned with local reactions to chemical compounds, from this site select: Allergic Skin Reactions and Role of the Allergist/Immunologist
Type II, III Hypersensitivity