Core Immunology - Diagnosis of Autoimmune Diseases (10) Flashcards Preview

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Flashcards in Core Immunology - Diagnosis of Autoimmune Diseases (10) Deck (32)
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1
Q

Types of diagnostic tests

A
  1. Non-specific - inflammatory markers

2. Specific - autoantibody test/HLA typing

2
Q

Non-specific inflammatory markers

A
  1. ESR
  2. CRP
  3. Ferritin
  4. Fibrinogen
  5. Haptoglobin
  6. Albumin
  7. Complement
3
Q

ESR (erythrocyte sedimentation rate)

A

Blood in capillary tube, see how long takes to drop to bottom, viscosity increases during inflammation

4
Q

CRP (c-reactive protein)

A

Liver rapidly produces and uses in an inflammatory response, activates complement system, activated by IL-6 secretion

5
Q

Ferritin

A

Elevated

6
Q

Fibrinogen

A

Elevated

7
Q

Haptoglobin

A

Binds to Hb allowing it to be degraded, elevated

8
Q

Albumin

A

Lowered

9
Q

Complement

A

SLE antibody leads to increase immune complexes, C3 and C4 decrease

10
Q

Sensitivity

A

Measure of how good the test is in identifiying people with the disease

11
Q

Specificity

A

Measure of how good the test is at correctly defining people without the disease

12
Q

Positive predicitive value

A

The proportion of people with a positive test who have target disorder

13
Q

Negative predictive value

A

The proportion of people with a negative test who don’t have the target disorder

14
Q

ANA

A

Extractable nuclear antigens

15
Q

Detection of ANA

A

Detect if antibodies against nucleus, serum and fibroblast-like cells on slide, secondary antibody added, recognises IgG with fluorescent markers

16
Q

ANA present in

A

SLE, acute episode of illness (flu/infection), more in elderly

17
Q

Detection of Anti-dsDNA

A

Crithidia luciliae assay (protosoa), Farr assay, ELISA

18
Q

Detection of ENA’s

A

Immunoblots, individual ELISA’s, combination of antigens

19
Q

Detection of dsDNA and ENA’s

A

Used to work out specific target of ANA (>100 different antibodies described in SLE)

20
Q

ANA screen

A

dsDNA, Chromatin, ribosomal protein, SS-A, SS-B, Sm, Sm/RNP, Scl-70, Jo-1, Centromere B

21
Q

Multiplex assessment non-organ specific autoantibodies with novel microbead-based immunoassay

A

20/30 beads with internal colouring, attach bead to antigen e.g. dsDNA, use a secondary antibody - which antigen and what bead, use laser

22
Q

Rheumatoid factor

A

Antibody (IgM, IgG, IgA) directed against Fc portion of IgG, found in RA (70%) and chronic infections (vasculitis)

23
Q

Anti-CCP (ACPA)

A

95% specific RA, more severe and erosive disease

24
Q

Cytoplasmic (c)ANCA

A

Granular fluorescence of neutrophil cytoplasm with nuclear sparing

25
Q

(c) ANCA target antigens

A

PR3, Azurocidin, Lysozyme, MPO

26
Q

Perinuclear (p)ANCA

A

Apparent fluorescence of the nucleus only

27
Q

(p) ANCA target antigens

A

MPO, Azurocidin, B-glucuronidase, Cathepsin G, PR3

28
Q

Clinical utility of ANCA testing

A
  • Histopathology is gold standard for diagnosis
  • Neg ANCA doesn’t exclude vasculitis (10-50% neg)
  • Correlation between return of ANCA and disease flare is poor
  • Persistence of ANCA and no clinical signs - dont need treatment
29
Q

Autoimmune liver disease

A
  • Anti-mitochondrial Ab for primary biliary sclerosis

- Anti-smooth muscle and anti-liver/kidney/microsomal (LKS) Abs for autoimmune hepatitis

30
Q

How are autoimmune liver disease antibodies detected?

A

IF screening using rodent tissue block (oesophagus, liver and kidney) and antigen specific ELISA

31
Q

Autoantibodies in Type 1 DM

A
  • Islet cell antibodies
  • Anti-GAD65/67
  • Anti-insulinoma antigen 2 (IA-2)
  • Insulin autoantibodies (IAAs)
  • Disappear with progression of disease and total destruction of B islet cells
32
Q

Diagnosis and autoantibodies of Type 1 DM

A

Disease conformation, identify relatives and patients at risk

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