(8-20) Immune Disorders: Hypersensitivities

Question 1

How many types of hypersensitivities are important in microbiology?

Answer 1

Four

Question 2

What are the 3 possible disorders of the immune system?

Answer 2

1. Hypersensitivities (allergies)
2. Autoimmunity
3. Immunodeficiency

Question 3

What is the immune response that causes tissue injury?

Answer 3

Hypersensitivity (allergy)

Question 4

What causes a response against self-antigens?

Answer 4

Autoimmunity

Question 5

What causes a lack of immunological response?

Answer 5

Immunodeficiency

Question 6

Which type of hypersensitivity involves an immediate response and is IgE-mediated.

Answer 6

Type I

Question 7

Which type of hypersensitivity is cytotoxic?

Answer 7

Type II

Question 8

Which type of hypersensitivity is immune complex (Ab/Ag)-mediated?

Answer 8

Type III

Question 9

Which type of hypersensitivity is delayed cell-mediated?

Answer 9

Type IV

Question 10

Anaphylactic shock is an example of which type of hypersensitivity?

Answer 10

Type I

Question 11

Blood transfusion reactions are an example of which type of hypersensitivity?

Answer 11

Type II

Question 12

Disseminated intravascular coagulation in Gram-negative septicemia is an example of which type of hypersensitivity?

Answer 12

Type III

Question 13

Tuberculin reaction is an example of which type of hypersensitivity?

Answer 13

Type IV

Question 14

Can large parasites within the gut (ex. helminthes) be phagocytosed? Why or why not?

Answer 14

No. When a parasite is larger than a phagocytic cell it is physically impossible for phagocytosis to occur.

Question 15

How are large parasites within the gut dealt with?

Answer 15

1. Antigen from helminthes penetrates mucosa and binds (two or more) IgE on mast cells
2. Mast Cells produce inflammation of the mucosal surface
3. Leads to the “outflow” of antibody, complement, effectors cells of ADCC (NK cells and eosinophils)
4. Eosinophils produce toxic proteins against helminthes

Question 16

How do Mast Cells produce inflammation?

Answer 16

1. Mast cells have IgE antibodies on their surface.

2. IgE releases pro-inflammatory compounds (e.g., histamine) when antigen is bound

Question 17

What is the name given for IgE-mediated reaction? What type of reaction is it?

Answer 17

1. Anaphylaxis

2. Type I Hypersensitivity

Question 18

When is anaphylaxis an appropriate response?

Answer 18

During a helminth infection.

Question 19

What is Hay Fever?

Answer 19

Mast cell degranulation in the respiratory mucosa, due to IgE antibodies (on mast cells) against pollen grains. (Type I)

Question 20

What is another word for Wheal and Flare skin reaction, and what is a common cause?

Answer 20

Hives, caused by a Type I hypersensitivity to Lobster.

Question 21

If a sensitized-to antigen (IgE is on mast cells) gets widely disseminated through the entire body (via the blood), the widespread mast cell/basophil degranulation will lead to which 4 events? What is this called?

Answer 21

Anaphylactic Shock

1. Inflammation
~ Blood vessel dilation of ALL vessels
2. Rapid drop in blood pressure
3. Lack of blood (oxygen) delivered to critical tissue
4. Death

Question 22

Peanuts, bee stings, and penicillin are antigens that tend to result in what?

Answer 22

Anaphylactic Shock, a Type I Hypersensitivity

Question 23

What is the treatment for anaphylactic shock?

Answer 23

A shot of adrenalin (epinephrine)

Question 24

Complement-binding antibodies bind to the surface of cells, leading to destruction or ADCC in which type of sensitivity?

Answer 24

Type II

Question 25

What is Disseminated Intravascular Coagulation?

Answer 25

The blockage of small capillaries (ex. in kidney), due to an excess of antigen creating many small immune complexes that initiate blood clotting and inflammation.

Question 26

Delayed hypersensitivities (Type I) caused by what?

Answer 26

Cell-mediated immunity

Question 27

List 3 examples of Type IV hypersensitivities.

Answer 27

1. Poison ivy and poison oak
2. Latex products
3. Tuberculin skin test

Question 28

When does response to antigen peak in a Type IV hypersensitivity?

Answer 28

Reactions peak in 2 to 3 days

Question 29

Which type of cell is responsible for Type IV hypersensitivities and what is the mechanism?

Answer 29

T cells release cytokines that attract macrophages and add to inflammation.

Question 30

What does a positive Tuberculin skin test

result from?

Answer 30

After introduction of small quantities of protein antigens from tubercle bacillus into skin, the test injection site reddens and gradually thickens, resulting from sensitized T cells, release of cytokines, and influx of macrophages.