The allergic response
An allergy is an abnormal reaction or hypersensitivity of the body to a previously encountered allergen. An allergen is an antigen that causes an abnormal immune response; the immune system "over-reacts" to a threat that is harmless to most individuals. Allergens cause the release of specific antibodies in the lymphoid tissues. These antibodies are called IgE and are released from B cells. These IgE antibodies bind to mast cells and the allergen. Mast cells are found in connective tissue and blood vessels and they store and release histamine.
When the same allergen is encountered for a second time it binds to the mast cell and IgE antibody which triggers the release of histamine. Histamine is responsible for the contraction of smooth muscles. Because mast cells are found in abundance in the lining of the lungs, histamine is being released near the lungs and therefore the tubules tend to decrease in diameter. This is why difficulty breathing is suffered. Histamine also causes vasodilation (dilation of blood vessels) and permeability of blood vessel walls which allows an increased blood flow to the area and allows cells to move into the surrounding tissues. This causes swelling and inflammation, both symptoms of an allergic reaction. |
Treatments for allergies include:
1. Desensitisation: involves repeated exposure of the allergen until the allergic response dies down. The dosage of the allergen starts off small but increases after every treatment. The antigen links to the IgE during treatments, which makes less IgE available for binding and therefore future reactions.
2. Antihistamines: drugs that counteract the effect of histamine. This means the allergic response is prevented
3. Cortisone: a type of steroid drugs that suppress the immune system
1. Desensitisation: involves repeated exposure of the allergen until the allergic response dies down. The dosage of the allergen starts off small but increases after every treatment. The antigen links to the IgE during treatments, which makes less IgE available for binding and therefore future reactions.
2. Antihistamines: drugs that counteract the effect of histamine. This means the allergic response is prevented
3. Cortisone: a type of steroid drugs that suppress the immune system