Disorders Associated With The Immune System |
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1. Define:
2. Describe Type I hypersensitivity. 3. Differentiate between and describe systemic and local anaphylaxis reactions. 4. Describe how anaphylactic reactions can be prevented. 5. Describe the desensitization process to prevent allergic reactions. |
Hay fever, transplant rejection, and autoimmunity are examples of harmful immune reactions.
Infection and immunosuppression are examples of failure of the immune system.
Superantigens activate many T-cell receptors, resulting in the release of excessive amounts of cytokines that can cause adverse host responses.
Hypersensitivities are altered immune reactions (in response to an antigen) leading to tissue damage, pretty much the same thing as an allergy.
An allergen is an antigen that stimulates a hypersensitivity response.
Classes:
Anaphylaxis reactions involve adjacent IgE antibodies bound to basophils and/or mast cells that are cross-linked by binding to antigen.
This results in the release of mediators (histamine, leukotrienes and prostaglandins) that cause inflammation.
There are two basic kinds of reactions: systemic anaphylaxis and localized reactions.
Systemic anaphylaxis is anaphylactic shock and can be counteracted by epinephrine injection.
Localized reactions include allergic rhinitis (hay fever) accompanied by itchy and teary eyes, congestion, coughing and sneezing; asthma, accompanied by wheezing and shortness of breath; and hives, a skin rash usually due to food allergies.
Anaphylactic reactions can be prevented by determination of the specific allergens that a patient is sensitive to and injecting small amounts of the allergens over an extended period of time (desensitization). This causes the production of blocking antibodies, which are IgG.
The only other treatment is symptomatic, such as with antihistamines.
The Mechanism of Anaphylaxis
Localized Anaphylaxis
Skin Test to Identify Allergens
