Hypersensitivity

Question 1

Hypersensitivity is dependent on

Answer 1

Presence of an antigen and T cell sensitized to antigen

Question 2

Hypersensitivity Type 1 is an …

Answer 2

IgE mediated immediate hypersensitivity reaction

Question 3

3 types of type 1 hypersensitivity

Answer 3

1. Allergic reaction
2. Anaphylaxis
3. Atopic hypersensitivity

Question 4

Type 1 hypersensitivity reaction time

Answer 4

15-30 mins

Question 5

Biphasic reaction

Answer 5

A second reaction, that usually occurs within 8 hours of the initial reaction, but may occur 24 to 72 hours post exposure

Question 6

Hypersensitivity Type 1 reaction manifestations (7)

Answer 6

Itching, localized swelling, throat tightness, wheezing, SOB, tachycardia, hypotension

Question 7

List 6 Steps to Hypersensitivity Type 1 Pathogenesis

Answer 7

1. First exposure to antigen results in APC attaching to helper T cell, presenting antigen on MHC2
2. Class switching results in antibody IgE production instead of IgG or IgM
3. All of the IgE antibodies bind to Fc receptors on mast cells (mast cell sensitization)

Second exposure

4. Antigen (allergen) binds to mast cells and cross links with other antibodies
5. Degranulation of mast cells and lots of release of histamine
6. Signs and symptoms of inflammation

Question 8

Primary early response symptoms of hypersensitivity type 1(3)

Answer 8

Vasodilation
Vascular damage
Smooth muscle spasm

Question 9

Second late response symptoms of hypersensitivity type 1 (5)

Answer 9

mucosal edema
mucous secretion
leukocyte infiltration
epithelial damage
bronchospasm

Question 10

Hypersensitivity Type 2 is a …. reaction… also known as ….

Answer 10

immediate hypersensitivity reaction also known as cytotoxic or cytolytic hypersensitivity

Question 11

Hypersensitivity Type 2 reaction time

Answer 11

15-30 mins

Question 12

Two examples of type 2 hypersensitivity reaction

Answer 12

ABO transfusion reaction
Hemolytic disease of the newborn

Question 13

3 Steps of Hypersensitivity Type 2 Patho

Answer 13

1. Triggers by exposure to antigen on surface of foreign cells
2. IgG or IgM antibodies bind to antigens to form antigen-antibody complex
3. Antigen-antibody complex initiates the complement cascade via classic pathway. MAC (C5-C9) lyses the foreign cells

Question 14

Hypersensitivity type 3 is also known

Answer 14

as an immune complex mediated hypersensitivity reaction

Question 15

Why does hypersensitivity type 3 occur?

Answer 15

Typically occurs due to exposure to an excessive amount of antigen usually over a prolonged
period of time such as in the case of a persistent infection

Question 16

Where can hypersensitivity type 3 occur?

Answer 16

glomerulonephritis (kidney), rheumatoid arthritis (joint), and
in systemic lupus erythematosus (many organs)

Question 17

Pathogenesis of type 3 hypersensitivity

Answer 17

1. Antigen forms antigen-antibody complexes that precipitate out of fluid and deposit into tissue
2. Most antigen-antibody complexes are removed before they can cause harm, but in this instance they don’t and lead to tissue injury
3. Deposition of immune complexes on tissue result in enzymes being released and activation of complement = surrounding cells get injured too

Question 18

Glomerulonephritis patho example

Answer 18

Small complexes are removed more easily from the body but in the case of glomerulonephritis the complexes are not able pass through the glomerular basement membrane and into the urine.

The large Ag-Ab complexes become lodged in the glomerular
capillary wall and are phagocytized because they are easily marked due to their size causing injury to the glomerular basement membrane

Question 19

What is type 4 hypersensitivity?

Answer 19

Cell mediated hypersensitivity response controlled by T lymphocytes, no antibodies involves

Question 20

Time line of hypersensitivity type 4?

Answer 20

The reaction peaks 24 to 72 hours but can last as long as 14 days after exposure to the antigen

Question 21

4 examples of hypersensitivity type 4

Answer 21

1. contact dermatitis
2. tb skin test
3. granuloma formation
4. graft vs host disease

Question 22

Blank

Answer 22

need to delete