Autoimmune disease, Allergy and Diagnosis Flashcards
(32 cards)
What is positive selection in central tolerance?
T cells undergo positive selection in the thymus
T cells need to be able to bind to MHC in order to survive .
What is negative selection in central tolerance?
B cells and T cells undergo negative selection in the bone marrow and thymus respectively
B cells and T cells that react with self antigens are eliminated
Which genes encode for MHC class I?
genes in HLA-A, HLA-B, HLA-C
Which genes encode for MHC class II?
genes in HLA-DP, HLA-DQ, HLA-DR
mutation of FoxP3 causes what?
mutation of FoxP3 causes failure to develop regulatory T cells – severe autoimmunity from birth
Associated with:
Immune dysregulation, polyendocrinopathys, enteropathy
mutations in PTPN22 cause what?
mutations in PTPN22 cause T cells to be activated more easily – stronger immune response in general
Associated with:
Type 1 diabetes, Rheumatoid arthritis, autoimmune thyroid disease
What is an example of an infection causing autoimmunity due to molecular mimicry?
Rheumatic fever
antibodies against M protein of Streptococcus A also react against the glycoproteins of the heart
Which parts of the immune system are involved in autoimmunity?
Adaptive immunity B and T cells Break down of self tolerance Autoantibodies present Continuous progression of clinical features
eg. Rheumatoid Arthritis and SLE
Which parts of the immune system are involved in autoinflammation?
Innate immunity
Neutrophils and macrophages
Few or no autoantibodies
Recurrent, seemingly unprovoked attacks
eg. Crohn’s diease
What is sensitivity of a diagnostic test?
measure of how good is the test in identifying people with the disease
What is specificity of a diagnostic test?
measure of how good is the test at correctly defining people without the disease
What is the positive predictive value of a diagnostic test?
The proportion of people with a positive test who have the target disorder
What is the negative predictive value of a diagnostic test?
The proportion of people with a negative test who do not have the target disorder.
What is C- reactive protein?
CRP is produced in the liver during an acute phase reaction in response to IL-6.
It binds to the phosphocholine expressed on the surface of dead or dying cells and some bacteria.
This activates the complement system, promoting phagocytosis by macrophages
How is C-reactive protein useful as a diagnostic marker of inflammation?
Measuring and charting CRP values can prove useful in determining disease progress or the effectiveness of treatments
CRP is a more sensitive and accurate reflection of acute phase response than ESR
What are the ENA’s ?
Extractable Nuclear antigens (ENAs)
The six main antigens used in immunological laboratories for detection are:
Ro, La, Sm, RNP, Scl-70 and Jo1,
Which autoantibody is more sensitive for diagnosing SLE and which is most specific?
ANA is most sensitive (>95%)
but less specific (60%)
dsDNA is less sensitive (70%)
but most Specific (95%)
Which autoantibody is most specific for rheumatoid arthritis?
Anti-citrullinated protein antibody (ACPA)
95% specificity
ACPA positive patients tend to have more severe and erosive disease
What antigen is most likely to be the target of autoantibodies in Cytoplasmic ANCA?
PR3 (90%) in cANCA
What antigen is most likely to be the target of autoantibodies in Perinuclear ANCA?
MPO (70%) in pANCA
What are the ANCA associated systemic vasculitidies? (AASV)
Microscopic polyangiitis
Granulomatosis with polyangitis
(Wegener’s granulomatosis)
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
What are anti-mitochondrial Ab specific for?
Primary biliary sclerosis
What are anti-smooth muscle and anti-Liver kidney microsomal type 1 (LKS) autoantibody found in?
autoimmune hepatitis
What autoantibodies are found in Type I diabetes mellitus?
islet cell antibodies
anti-GAD65, anti-GAD67
anti-insulinoma antigen 2 (IA-2)
insulin autoantibodies (IAAs)
Disappear with progression of disease and total destruction of β islet cells
