Term
| What is hypersensitivity? |
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Definition
| It's excessive undesirable reactions produced by normal immune system that requires revious exposure to offending antigen. |
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Term
| What are two different types of Antigens? |
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Definition
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Term
| What are exogenous antigens? |
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Definition
| Antigens from the ouside of the body such as flea saliva, dust mites, and pollen... can lead to allergic dermatitis |
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Term
| What are endogenous antigens? |
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Definition
They are self antigens that the body does not recognize as Self
EXAMPLE: antigens ont he patient's own RBC leads to Autoimmune Hemolytic Anemia |
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Term
| What are hypersensitivity reactions? |
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Definition
They are allergic disorders that can be more than one type of hypersensitivity inovlved in a particular clinical condition.
Types I, II, III, IV |
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Term
| What is Type 1 Hypersensitivity (immediate/anaphylactic) |
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Definition
It's mediated by IgE and mast cells or basophils
On first contact: IgE is produced in tissues exposed to antigents and becomes fixed to the surfaces of mast cells
On first contact, IgE is not released into the general circulation, however on re-exposure, the Ag-Ab complexes form on the surfaces of mast cells, causing them to degranulate and occurs immediately
Degranulation of mast cells releases histamine which causes increased vascular permeability and edema because of an accumulation of inflammatory cells.
Eosinophilia results and response occurs within 10-12 hours after reexposure to antigen |
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Term
| List Type 1 Hypersensitivity Examples: |
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Definition
1. hay fever in people
2. People allergic to cat dander
3. Allergic dermatitis
4. Anaphylactic shock |
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Term
What is Type II Hypersensitivity
(Cytotoxic Sensitivity) |
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Definition
It's mediated by IgG, IgM and complement
The antigens are usually endogenous an react with antigenic body cell membranes and results in lysis |
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Term
List some Examples of Type II Hypersensitivity
(Cytotoxic Sensitivity) |
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Definition
Hemolytic anemia
Transfusion Reactions |
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Term
Describe Type III Hypersensitivity
(Immune Complex Hypersensitivity) |
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Definition
Mediated by immune complexes formed by antigens and antibodies (IgG/IgM)
These complexes are soluble and reaction may be generalized or they may be deposited in and affect specific organs and causes acute inflammation |
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Term
| How can type III hypersensitivity be demonstrated? |
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Definition
| With Immunofluorescence microscopy |
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Term
| List examples of Type III Hypersensitivity: |
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Definition
Serum Sickness in People given Horse Serum
Systemic Lupus Erythematosus
(ag-ab complexes deposited in kidneys, joints, skin) |
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Term
Describe Type IV Hypersensitivity
(Cell-mediated/Delayed Type Hypersensitivity) |
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Definition
| Characterized by erythema and induration (localized hardening of tissue) |
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Term
| List some examples of Type IV hypersensitivity: |
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Definition
Tuberculin Reaction
Contact Dermatitis -- Poison Ivy |
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Term
| What's involved in Type IV Hypersensitivity? |
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Definition
Involves T cells, monocytes, macrophages
Cells and antigens accumulate at the site to cause granulomas and contains mononulcear inflammatory cells (lymphocytes/macrophages) |
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