Autoimmunity

Question 1

What is an autoimmune disease?

Answer 1

Damage due to autoreactive T or B cell

Question 2

What is autoimmunity?

Answer 2

Self reacting cells present, not necessarily damaging/disease causing

Question 3

What are causes of immunopathologies?

Answer 3

• Defect response (Immunodeficiency)
• Excessive response (Inflammation if innate, hypersensitivity if adaptive)
• Inappropriate response against self (autoimmunity)

Question 4

What is a type I hypersensitivity?

Answer 4

Immediate hypersensitivity mediated by innocuous antigens (IgE response TH2 mediated)

Question 5

What is a type II hypersensitivity?

Answer 5

Cell associated, antibody-dependent cytotoxicity

Question 6

What is a type III hypersensitivity?

Answer 6

Immune complex mediated

Question 7

What is a type IV hypersensitivity?

Answer 7

Delayed type hypersensitivity

Question 8

What are some mechanisms of immune tolerance?

Answer 8

Deletion
Anergy
Ignorance
Failure of regulation

Question 9

What are some ways autoimmunity is developed?

Answer 9

• Mimicry
• Polyclonal B cell stimulation
• Exposure of previously sequestered self antigens
• Cytokine induction post infection

Question 10

What are some possible symptoms of a type I hypersensitivity?

Answer 10

• swollen lips
• difficulty breathing
• pruritis
• tachypnoea

Question 11

What is the pathogenesis of a type I hypersensitivity?

Answer 11

• Allergen activates Th2 response
• B cells create IgEs
• Mast cells degranulate
• Histamine release

Question 12

How could you treat type I hypersensitivity such as walnut allergy?

Answer 12

• adrenaline
• High flow O2
• ß2 agonist (bronchodilator)
• IV steroids
• anti-histamines

Question 13

A patient presents with fever, impetigo, pansystolic murmur and painful swollen right knee and left ankle. What would you expect from the gram stain and plates of a pathogen that contributed to this presentation?

Answer 13

Strep. pyogenes so:
gram +ve dipplococci

HBA O2 better growth, ß haemolytic

Question 14

What are some possible complications of strep pyogenes infection?

Answer 14

• septicemia
• endocarditis
• toxic shock syndrome
• septic arthritis

Question 15

What is the basis of autoimmune endocarditis?

Answer 15

• M proteins in the cardiac tissue cross react post strep pyogenes infection
• Cause B and T cell response against own cardiac tissue

Question 16

What is rheumatic fever?

Answer 16

Autoimmunity following strep infection that can present in many ways such as polyarthritis or carditis

Question 17

What are some long term treatments for a patient with autoimmune endocarditis?

Answer 17

Long term penicillin to prevent recurrence of a strep pyogenes infection

Question 18

A patient presents with a florid rash on her cheeks and face as well as joint pain. What is your likely diagnosis?

Answer 18

SLE

Question 19

What type of hypersensitivity is SLE?

Answer 19

Type III

Question 20

A patient with SLE has not travelled recently and has not been unwell. What is a possible trigger for this disease in this patient?

Answer 20

Sunlight which causes necrosis and the release of nuclear antigens to which antibodies are produced causing immune complexes

Question 21

What tests are appropriate for SLE?

Answer 21

• Anti-nuclear test which is for antibodies against dsDNA which is normally within cells
• Dipstick to look for nephritis

Question 22

A patient presents with diarrhoea and fever. A gram -ve rod is found in faecal specimens which is a non-lactose fermenter but is a mannitol fermenter. What is the pathogen?

Answer 22

Yersinia Enterocolitica

Question 23

How do you treat Yersinia Enterocolitica?

Answer 23

Gentamicin, NSAIDs if there is reactive arthritis

Question 24

What is Righter’s syndrome?

Answer 24

Reactive arthritis, where post infection cross-reacting antibodies cause disease

Question 25

Are anti-nuclear antibodies sufficient to diagnose SLE?

Answer 25

No, predictive value is too low