Autoimmunity Flashcards
What is an autoimmune disease?
Damage due to autoreactive T or B cell
What is autoimmunity?
Self reacting cells present, not necessarily damaging/disease causing
What are causes of immunopathologies?
- Defect response (Immunodeficiency)
- Excessive response (Inflammation if innate, hypersensitivity if adaptive)
- Inappropriate response against self (autoimmunity)
What is a type I hypersensitivity?
Immediate hypersensitivity mediated by innocuous antigens (IgE response TH2 mediated)
What is a type II hypersensitivity?
Cell associated, antibody-dependent cytotoxicity
What is a type III hypersensitivity?
Immune complex mediated
What is a type IV hypersensitivity?
Delayed type hypersensitivity
What are some mechanisms of immune tolerance?
Deletion
Anergy
Ignorance
Failure of regulation
What are some ways autoimmunity is developed?
- Mimicry
- Polyclonal B cell stimulation
- Exposure of previously sequestered self antigens
- Cytokine induction post infection
What are some possible symptoms of a type I hypersensitivity?
- swollen lips
- difficulty breathing
- pruritis
- tachypnoea
What is the pathogenesis of a type I hypersensitivity?
- Allergen activates Th2 response
- B cells create IgEs
- Mast cells degranulate
- Histamine release
How could you treat type I hypersensitivity such as walnut allergy?
- adrenaline
- High flow O2
- ß2 agonist (bronchodilator)
- IV steroids
- anti-histamines
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?
Strep. pyogenes so:
gram +ve dipplococci
HBA O2 better growth, ß haemolytic
What are some possible complications of strep pyogenes infection?
- septicemia
- endocarditis
- toxic shock syndrome
- septic arthritis
What is the basis of autoimmune endocarditis?
- M proteins in the cardiac tissue cross react post strep pyogenes infection
- Cause B and T cell response against own cardiac tissue
What is rheumatic fever?
Autoimmunity following strep infection that can present in many ways such as polyarthritis or carditis
What are some long term treatments for a patient with autoimmune endocarditis?
Long term penicillin to prevent recurrence of a strep pyogenes infection
A patient presents with a florid rash on her cheeks and face as well as joint pain. What is your likely diagnosis?
SLE
What type of hypersensitivity is SLE?
Type III
A patient with SLE has not travelled recently and has not been unwell. What is a possible trigger for this disease in this patient?
Sunlight which causes necrosis and the release of nuclear antigens to which antibodies are produced causing immune complexes
What tests are appropriate for SLE?
- Anti-nuclear test which is for antibodies against dsDNA which is normally within cells
- Dipstick to look for nephritis
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?
Yersinia Enterocolitica
How do you treat Yersinia Enterocolitica?
Gentamicin, NSAIDs if there is reactive arthritis
What is Righter’s syndrome?
Reactive arthritis, where post infection cross-reacting antibodies cause disease
