Allergy

Front 1

Define:

Allergy

Back 1

a specific type of immune response elicited by exposure to an antigen

Front 2

antigen

Back 2

a substance that can generate an immune response

Front 3

What are the four types of hypersensitivity reactions/allergy?

Back 3

I. Immediate
II. Antibody Mediated
III. Immune Complex Mediated
IV. Cell Mediated

Front 4

What is the mechanism of Immediate Hypersensitivity (Type I)?

Typical diseases:
Typical Symptoms:

Back 4

1. Initial exposure to allergen triggers B-cells to make IgE
2. IgE bind to surface of mast cells
3. Upon subsequent exposure, allergen binds to IgE on mast cells, triggering release of granules (mediators) from mast cells

Diseases: asthma, hay fever, anaphylaxis
Symptoms: runny nose, sneezing, congestion, wheezing, coughing

Front 5

What is the mechanism of Antibody Mediated Hypersensitivity (Type II)?

Typical diseases:
Typical Symptoms:

Back 5

1. IgG or IgM produced by B-cells
2. Antibody binds to host tissue
3. Host tissue targeted for destruction by neutrophils (phagocytosis), Natural Killer Cells, or lysis by complement proteins

Diseases: autoimmune disorders, Goodpasture syndrome
Symptoms: dependent upon organ involvement (i.e. blood- cytopenias)

Front 6

anaphylaxis

Back 6

severe and potentially lethal manifestation of immediate hypersensitivity

consists of hypotension and respiratory distress

treatment is with epinephrine

Front 7

Describe the long-term pathophysiology of asthma

Back 7

1. hypersensitivity causes bronchoconstriction and huge amounts of mucous in airways
2. repeated episodes of bronchoconstriction lead to smooth muscle hypertrophy

Front 8

How does circulatory failure occur in anaphylaxis?

Back 8

hypotension due to
1. vasodilation
2. low circulating volume caused by vascular leakage

Front 9

How does respiratory failure occur in anaphylaxis?

Back 9

obstruction of airways due to:
1. bronchoconstriction from smooth muscle contraction
2. obstruction from laryngeal edema (accumulation of mucous)

Front 10

What are the five types of antibodies?

Back 10

MADGE

Front 11

Describe the pathophysiology of Goodpasture Syndrome

Back 11

Type II Hypersensitivity

1. auto-antibodies bind proteins in the basement membrane of the lung and kidney
2. respiratory and renal failure result due to compromise of air exchange and filtration

Front 12

Describe the pathophysiology of Lupus

Back 12

Type III hypersensitivity

1. auto-antibodies bind to proteins in nuclei of cells forming immune complexes
2. immune complexes deposit in blood vessels of organs
3. deposited immune complexes stimulate tissue destruction

Front 13

What is the Arthus reaction?

Back 13

Type III hypersensitivity

some people who were vaccinated with horse serum developed arthritis, skin rash, and fever after subsequent immunizations

Front 14

What is the mechanism of Immune Complex Mediated Hypersensitivity (Type III)?

Typical diseases:
Typical Symptoms:

Back 14

1. formation of immune complexes (globs of antibody bind to antigen)
2. Immune complexes deposit in small blood vessels
3. Deposited immune complexes stimulate local inflammation and tissue destruction

Diseases: Lupus, Arthus reaction
Symptoms: rash, inflammation, arthritis, fever, tissue damage

Front 15

What is the mechanism of Cell Mediated Hypersensitivity (Type IV)?

Typical diseases:
Typical Symptoms:

Back 15

1. Activated T-cells directly kill targeted cells or helper T-cells activate macrophages

Disease: dermatitis (poison ivy), organ transplant rejection, granuloma formation, autoimmune diseases
Symptoms: varied

Front 16

Describe the pahtophysiology of granuloma formation.

Back 16

Type IV hypersensitivity

1. Foreign material activates T-cells
2. Activated T-cells activate macrophages
3. Macrophages enlarge and group together into a granuloma
4. The granuloma isolates and contains infections or foreign bodies

Front 17

sarcolysis

Back 17

a disease characterized by numerous granulomas, especially in the lungs, related to an excessive cell mediated hypersensitivity response

Front 18

Mast Cell

Back 18

A specialized type of WBC found in tissue near blood vessels that contain granules filled with biologically active mediators such as histamine. Surface is covered with binding sites for IgE antibodies which trigger release of granules = hypersensitivity