THE ALLERGIC RESPONSE
Allergic responses occur due to an overstimulation of the immune system upon renewed exposure to an antigen (allergen). This reaction to the allergen causes symptoms such as inflammation that can range from mild to severe which would otherwise be harmless to others. Allergens can be exposed to the body and its immune system by different mediums such as ingestion by food, ingestion by inhalation, contact by skin and by injection. When the body first comes into contact with the allergen, B cells differentiate into plasma cells and produce a large amount of a specific antibody.
Upon first detection of the allergen by the immune system, an antibody called immunoglobulin E (IgE) is produced in large amount by B cells that have differentiated into plasma cells. The IgE antibodies bind to mast cells, basophils and other white blood cells lining the respiratory and digestive systems. When the allergen is introduced in the body and detected subsequently, it will bind to the IgE antibodies located on the mast cells. This causes the mast cells to be stimulated or primed and cause them to release a compound known as histamine which is also required in inflammatory responses. The increased concentration of histamine causes the expansion of blood vessels, causing an increase in blood flow and thus, inducing inflammatory effects. When the allergen is encountered by the body, it will bind to the IgE located on the mast cells, causing a release of previously stored histamine. The histamine released causes inflammatory responses such as the contraction of smooth muscle as a result of dilated blood vessels, causing increased blood flow and reduced airways to the lungs, decreasing the ease of breathing. In a normally functioning immune system, allergens would be harmless to the body and will not induce inflammatory responses.
An extreme allergic reaction is known as anaphylaxis. During anaphylaxis, large amounts of histamine are released, leading to symptoms such as swelling of the throat tissue, fall in blood pressure.
Allergic reactions can be treated by desensitising, antihistamines, anti-inflammatory drugs and steroids. Desensitising involves exposure to the allergen in small doses and gradually increasing the doses. Injected allergens will bind to IgE antibodies on mast cells. On a second encounter with the allergen, no response is carried out as there are no vacant antibodies for the allergens to attach to. Antihistamines are drugs designed to inhibit the body’s receptors for histamine, suppressing the response of the allergen but not the rest of the immune system.
Allergic responses occur due to an overstimulation of the immune system upon renewed exposure to an antigen (allergen). This reaction to the allergen causes symptoms such as inflammation that can range from mild to severe which would otherwise be harmless to others. Allergens can be exposed to the body and its immune system by different mediums such as ingestion by food, ingestion by inhalation, contact by skin and by injection. When the body first comes into contact with the allergen, B cells differentiate into plasma cells and produce a large amount of a specific antibody.
Upon first detection of the allergen by the immune system, an antibody called immunoglobulin E (IgE) is produced in large amount by B cells that have differentiated into plasma cells. The IgE antibodies bind to mast cells, basophils and other white blood cells lining the respiratory and digestive systems. When the allergen is introduced in the body and detected subsequently, it will bind to the IgE antibodies located on the mast cells. This causes the mast cells to be stimulated or primed and cause them to release a compound known as histamine which is also required in inflammatory responses. The increased concentration of histamine causes the expansion of blood vessels, causing an increase in blood flow and thus, inducing inflammatory effects. When the allergen is encountered by the body, it will bind to the IgE located on the mast cells, causing a release of previously stored histamine. The histamine released causes inflammatory responses such as the contraction of smooth muscle as a result of dilated blood vessels, causing increased blood flow and reduced airways to the lungs, decreasing the ease of breathing. In a normally functioning immune system, allergens would be harmless to the body and will not induce inflammatory responses.
An extreme allergic reaction is known as anaphylaxis. During anaphylaxis, large amounts of histamine are released, leading to symptoms such as swelling of the throat tissue, fall in blood pressure.
Allergic reactions can be treated by desensitising, antihistamines, anti-inflammatory drugs and steroids. Desensitising involves exposure to the allergen in small doses and gradually increasing the doses. Injected allergens will bind to IgE antibodies on mast cells. On a second encounter with the allergen, no response is carried out as there are no vacant antibodies for the allergens to attach to. Antihistamines are drugs designed to inhibit the body’s receptors for histamine, suppressing the response of the allergen but not the rest of the immune system.