Immune Disorders

Question 1

What is a hypersensitivity reaction?

Answer 1

A reaction due to an exaggerated or inappropriate adaptive immune response to an antigen/immunogen causing tissue damage

Question 2

How many hypersensitivity reactions are there?

Answer 2

4

Question 3

What are the 4 types of hypersensitivity reactions?

Answer 3

Immediate (type I)
Cytotoxic (type II)
Complex mediated (type III)
Delayed (type IV)

Question 4

What is immediate hypersensitivity?

Answer 4

An immediate reaction after contact with an immunogen (allergen)

Question 5

What is anaphylaxis?

Answer 5

A generalised type I reaction, leading to vasodilation and constriction of bronchial smooth muscle that can result in death

Question 6

Which antibody mediates type I hypersensitivity?

Answer 6

Ig E

Question 7

What is an allergen and give examples?

Answer 7

An immunogen that causes an allergy

EG. pollen, animal dander and drugs like penicillin

Question 8

What are the type of mast cell granules?

Answer 8

Histamine
Eosinophil chemotactic factor
Neutrophil chemotactic factor

Question 9

What is type II hypersensitivity?

Answer 9

Antibodies are directed against antigens on the surface of specific cells or tissues

Question 10

What antibodies mediate type II hypersensitivity

Answer 10

Ig M

Ig G

Question 11

What are the consequences of an antibody binding to an antigen?

Answer 11

Complement activation

Question 12

What does compliment activation lead to?

Answer 12

Cell lysis
Deposition of complement components (opsonisation)
Macrophage and neutrophil activation

Question 13

What are some examples of type II hypersensitivity?

Answer 13

Blood transfusion
Hyperacute graft rejection
Haemolytic disease of newborns
Goodpasture’s syndrome

Question 14

What is haemolytic disease of the newborn?

Answer 14

Rhesus incompatibility

Question 15

What are the effects of rhesus incompatibility

Answer 15

Spontaneous abortion

Born with mild jaundice or HDN

Question 16

What is type III hypersensitivity?

Answer 16

Antibodies are directed against soluble antigens in serum
Can also be directed against widely distributed antigen
Deposited antigen-antibody complexes then lead to damage in affect organs

Question 17

What are some examples of type III hypersensitivity?

Answer 17

Persistent infections where antibodies are formed against microbial agents (Chronic hep B)
Autoimmunity where antibodies formed against self antigens and immune complexes

Question 18

What are the nature of immune complexes?

Answer 18

Can be precipitates which cause problems locally

Can be soluble, which cause problems mainly in kidney, blood vessels and joints

Question 19

What is intrinsic allergic alveolitis?

Answer 19

An occupational disease due to inhalation of immunogenic proteins or spores

Question 20

What are examples of intrinsic allergic alveolitis?

Answer 20

Farmer’s lung
Mushroom worker disease
Coffee worker disease

Question 21

What is Farmer’s lung?

Answer 21

Mild cough that progresses into emphysema
Sensitisation to spores of thermophilic actinomycetes which grow in damp hay
Years of exposure lead to high levels of Ig G
Immune complexes then precipitate in lungs

Question 22

How does precipitate in farmers lung cause emphysema?

Answer 22

Complement activates
Initiates inflammation
Destroys alveolar tissue
Fibrosis (tissue repair)

Question 23

What is the treatment for Farmer’s lung?

Answer 23

Early diagnosis
Avoidance
Corticosteroids

Question 24

What is serum sickness?

Answer 24

Sickness following treatment of an active infection with antibodies
For example, treating diptheria using serum from a horse immunised against diptheria

Question 25

How long does it take to develop serum sickness symptoms and what are they?

Answer 25

``` 7 days Weakness Pains Fever Rash Oedema ```

Question 26

How long does it take for type IV hypersensitivity reactions to occur?

Answer 26

72 hours to weeks

Question 27

What is contact hypersensitivity mediated by?

Answer 27

T lymphocytes | Macrophages

Question 28

What is contact hypersensitivity?

Answer 28

Dermatitis caused by exposure to biological stains, hair dye, poison ivy, nickel salts and mercuric salts (tattoos)

Question 29

What is the treatment for type IV hypersensitivity?

Answer 29

Avoidance Corticosteroid creams Desensitisation

Question 30

What is sensitisation

Answer 30

Initial contact leading to a cell mediated immune response

Question 31

What is autoimmunity?

Answer 31

A breakdown of self tolerance

Question 32

What is self tolerance?

Answer 32

Failure to respond to self antigens

Question 33

What are two types of self tolerance?

Answer 33

Central tolerance | Peripheral tolerance

Question 34

What is self tolerance?

Answer 34

Deletion of self reactive T cells

Question 35

What is peripheral tolerance?

Answer 35

Clonal anergy Deletion Active suppression Presence of autoreactive B cells

Question 36

What causes the stimulation of self reactive lymphocytes?

Answer 36

Failure to eliminate self reactive lymphocytes Failure of suppression Occur after microbial infections

Question 37

What are the two types of autoimmunity?

Answer 37

Organ specific | Systemic

Question 38

What is organ specific autoimmunity?

Answer 38

Auto antigen localised to one organ

Question 39

What factors influence susceptibility to autoimmunity?

Answer 39

Genetics Environment Hormonal

Question 40

What are the two types of immunodeficiency?

Answer 40

Primary | Acquired/secondary

Question 41

What is primary immunodeficiency?

Answer 41

T cell defect B cell defect Phagocytosis defect Complement defect

Question 42

What causes secondary immunodeficiency?

Answer 42

Malnutrition Treatment (X-rays) Infection (HIV)