Immune Disorders

Question 1

Reactive arthritis

Answer 1

Infection with certain bacteria presents antigens that cross-react with antigens in the joints

Question 2

Sympathetic ophthalmia

Answer 2

Damage to the good eye after trauma or surgery to the other – these antibodies are normally hidden or sequestered from the immune system. A type of frank autoimmune disease.

Question 3

Autoimmune orchitis

Answer 3

Damage to the testicles following mumps or testicular trauma due to release of sperm antigens. A type of frank autoimmune disease.

Question 4

Rheumatic fever

Answer 4

Due to cross-reaction between streptococcal pyogenes antigens and antigens in cardiac muscle (and elsewhere)

Question 5

Thyrotoxicosis

Answer 5

Caused by antibodies against the TSH receptor which mimic the action of TSH and stimulate the thyroid gland (Graves)

Question 6

Pernicious anaemia

Answer 6

Due to malabsorption of vitamin B12 due to autoimmune destruction of the parietal cells in the stomach which produce intrinsic factor or antibodies against intrinsic factor itself

Question 7

Idiopathic thrombocytopenic pupura

Answer 7

Due to antibodies against platelets

Question 8

Addison’s disease

Answer 8

Due to destruction of the adrenal cortex

Question 9

Myasthenia gravis

Answer 9

Due to autoantibodies blocking the acetylcholine receptor on the neuromuscular endplate

Question 10

Rheumatoid arthritis

Answer 10

Type III hypersensitivity reaction

Soluble antigen and antibody complex precipitates and deposits in vessels and joints

Question 11

Goodpasture’s syndrome

Answer 11

Antibodies against type IV collagen in glomerular basement membrane, eventually leading to bleeding from the lungs and kidney failure

Question 12

Hashimoto’s disease

Answer 12

Antibodies against thyroid tissue itself, causing destruction of the thyroid rather than upregulation of the function as seen in Graves

Question 13

SLE treatment

Answer 13

Immunosuppressive drugs e.g., corticosteroids, azathioprine, cyclophosphamide

Question 14

SLE

Answer 14

Associated with deficiencies of complement components, thought to be due to impaired clearance of immune complexes. Systemic –symptoms include fever, rash, joint pain and fatigue.

Question 15

Urticaria

Answer 15

Itchy, raised, transient weals

Can be acute or chronic, often seen in anaphylaxis

Question 16

Bullous pemphigoid

Answer 16

Autoimmune reaction against two proteins in the hemidesmosomes which help stick the epidermis to the dermis
Can be neural, skin or muscular and these can cross-react to cause symptoms in more than one area

Question 17

Pemphigus vulgaris

Answer 17

Autoimmune reaction against desmogleins in the desmosomes that help keratinocytes stick to each other
Produces shallow blisters and skin erosions

Question 18

Pemphigus vulgaris treatment

Answer 18

Rituximab: depletes B cells

Question 19

Example of viral live attenuated vaccine

Answer 19

MMR, oral polio and chickenpox

Question 20

Example of bacterial live attenuated vaccine

Answer 20

TB and typhoid

Question 21

Example of reassorted live attenuated vaccine

Answer 21

Rotavirus

Question 22

4 types of inactivated vaccine

Answer 22

Whole/fractioned
Protein-based
Polysaccharide-based
Conjugate polysaccharide

Question 23

Examples of whole viral vaccine

Answer 23

Influenza, injected polio, rabies, Hep A

Question 24

Examples of whole bacterial vaccine

Answer 24

Pertussis, typhoid, cholera

Question 25

Examples of fractional vaccines

Answer 25

Subunits: Hep B, influenza
Toxoids: diptheria, tetanis

Question 26

Negatives of inactivated vaccines

Answer 26

Can’t get lifelong immunity just from one dose, repeat immunisation necessary

Question 27

How is the Hep B vaccine made?

Answer 27

Hep B is a recombinant vaccine where a segment of the Hep B virus gene is implanted into the yeast expression system

Question 28

LAIV

Answer 28

Live attenuated influenza vaccine

Recombinant vaccine engineered to replicate effectively the mucosa of the nasopharynx but not the lungs

Question 29

Tetanus

Answer 29

Caused by clostridium tetani, an anaerobic, spore-forming, gram-positive bacillus that is penicillin-sensitive
Spores are wide-spread, particularly in manure and soil
Easily introduced at time of injury, especially deep, penetrating, dirty wounds
Bacteria produces toxin called tetanospasmin toxin. Causes severe, painful muscle rigidity. Symptoms start about 10 days after exposure

Question 30

Neonatal tetanus

Answer 30

Entry via umbilicus to infant from unimmunised mother
Infant has no passive IgG immunity
Generally failure of aseptic technique during birth in developing world

Question 31

Passive immunisation for tetanus

Answer 31

Human or equine tetanus immunoglobulin – acquire immunity by transfer of serum from a donor to a non-immune person
Neutralises unbound toxin and shortens the course, lessens the severity of the disease and improves survival

Question 32

Passive immunisation advantages and disadvantages

Answer 32

Advantages: immediate protection
Disadvantages: no long-term protection, risk of transmission of other disease from donor, expensive, serum sickness risk

Question 33

Bordatella pertussis

Answer 33

Whooping cough
Deposited in respiratory tract by aerosol droplets produced by cough
3 stages: catarrhal phase (runny nose, conjunctivitis), paroxysmal phase (whooping), then convalescent phase (recovery, lasts weeks to months)

Question 34

Whooping cough treatment

Answer 34

Erythromycin – does little when illness already established, may shorten illness if started early but main advantage is decreased infectivity

Question 35

Whooping cough complications

Answer 35

Secondary bacterial infections such as pneumonia

Encephalopathy, seizures, apnoea

Question 36

Pertussis vaccine

Answer 36

1) Whole cell vaccine (old) – local and systemic reactions possible
2) Acellular vaccine – 3 dose primary schedule with 2 booster doses

Question 37

Poliomyelitis

Answer 37

Destroys lower motor neurons resulting in paralysis due to poliovirus

Question 38

Polio vaccine

Answer 38

Oral version is live and used in epidemics, however, inactivated polio vaccine is incredible effective and has lower risk of vaccine-associated paralytic polio disease

Question 39

Classifications of immunodeficiency

Answer 39

Congenital vs acquired

Primary vs secondary

Question 40

When should you suspect immunodeficiency?

Answer 40

When a patient has recurrent bacterial infections or infections with unusual organisms

Question 41

When should you suspect secondary immunodeficiency?

Answer 41

In patients taking steroid or cytotoxic drugs
In patients with known disease in other organ systems
In patients with lifestyle risk factors for HIV

Question 42

Antigen and antibody effects on immune responsiveness

Answer 42

The nature of the antigen affects the sorts of responses that are generated
How an antigen is processed and the nature of the MHC presentation structures affect which epitopes are available for recognition by T and B lymphocytes
Antibodies present in an individual at the time of antigen exposure can either enhance immune responses against the antigen by opsonisation or diminish responses by leading to rapid antigen removal

Question 43

Link between the nervous system and the immune system

Answer 43

Brain controls autonomic nervous system and the endocrine system. The endocrine system releases hormones, which is also regulated by the autonomic nervous system by feeding information through nerves. Nerves and hormones both affect the immune system, which releases cytokines, which affect the brain and the endocrine system.

Question 44

Effect of corticosteroids on the immune system

Answer 44

Corticosteroids produced by the adrenal cortex have profound immunosuppressive effects by depressing in vivo responses, depressing phagocytosis, inhibiting macrophage activation, inhibiting B and T cell activation and decreasing the number of cells in the thymus.