Immune-mediated disease in clinical practice – an overview Flashcards Preview

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Flashcards in Immune-mediated disease in clinical practice – an overview Deck (15)
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1
Q

Trigger factors

A
release of sequestered antigens
abnormal immunoregulation
molecular mimicry
polyclonal activation of T and B cells
exposure of cryptic epitopes, or haptenisation of foreign molecules to self antigens
2
Q

Role of infection

A

Break-down of vascular or cellular barriers - exposure of self-antigens
cell death by necrosis - infl
Polyclonal activation of T cells - bacterial superantigens
Molecular mimicry - cross-reactivity

3
Q

Aetiology

A

unclear in many autoimmune diseases

Genetic, infectious and hormonal influences

4
Q

History and physical exam.

A

remission and exacerbation
Lameness, mucocutaneous lesions, lethargy, dyspnoea, weight loss, PU/PD, ± seizures or behavioural changes
Effusive, painful joints; cutaneous erythema, macules, papules, pustules, erosion etc; pallor ± petechiae; cardiac arrhythmias; lymphadenomegaly ± splenomegaly

5
Q

Diagnostic tests: CBC/coags - results

A

Anaemia - Regenerative (IMHA), or non (infection,
uraemia, chronic bleeding, attack of precursors)
Thrombocytopaenia - immune-mediated (I-M) thrombocytopaenia
Leucopaenia? - Anti-leucocyte antibodies (eg. Systemic lupus erythematosus SLE, I-M neutropaenia)
Coagulation abnormalities - ↑ APTT, PT: ‘anticoagulant antibody’ (SLE), DIC

6
Q

Diagnostic tests: chem. panel - Azotaemia, ↑ inorganic phosphate - cause

A

Chronic glomerular lesions

7
Q

Diagnostic tests: chem. panel - Hypoalbuminaemia, hypercholesterolaemia - cause

A

Protein-losing nephropathy (PLN)

8
Q

Diagnostic tests: chem. panel - Hyperbilirubinaemia - cause

A

Pre-hepatic / haemolysis

9
Q

Diagnostic tests: chem. panel - Hyperglobulinaemia - cause

A

Infl disease, polyclonal B cell activation

10
Q

Diagnostic tests: chem. panel - ↑ Creatine kinase and lactate dehydrogenase- cause

A

Polymyositis and / or myocarditis

11
Q

Diagnostic tests: urinalysis

A

Proteinuria

Haematuria, pyuria, erythrocyte casts

12
Q

Radiography & arthrocentesis

A

Joint lesions common in polysystemic I-M disease
Erosive lesions suggest overlap syndrome
Arthritis is not always clinically obvious
Synovial fluid: ↑ WBC, ↑ proportion of neutrophils ± ↑ protein content, with ↓ viscosity + poor mucin clot formation

13
Q

Coombs’ test

A

If acute IMHA suspected - agglutination + osmotic fragility tests performed
Antibodies associated with surface of RBCs detected with the Coombs’ test
Primary reagent: polyvalent anti-dog or anti-cat
IgG, IgM & C3 antiserum (direct antiglobulin test)
False positive and negative reactions may occur

14
Q

Myasthenia gravis

A

auto-immune destruction of acetylcholine receptors at synapses
muscle weakness + atrophy

15
Q

Antinuclear antibodies (ANA)

A

Serum ANA – hallmark of human, canine and feline SLE
Indirect immunofluorescence or immuno-peroxidase test
False positives and false negatives may occur