Immune Mediated Disease Flashcards
What three underlying factors can trigger an immune mediated disease to develop?
Drug usage (that includes vaccines), Neoplasia or Infection
What do we mean when we talk about a spectrum of immune mediated disease?
Immune mediated disease can be organ or non organ specific e.g. effecting a bunch of tissues vs effecting one receptor
What goes wrong in an immune mediated disease?
The Immune system overreacts to normal tissue or harmless exogenous (self) proteins
What is the one thing necessary to perpetuate the start of an immune mediated disease?
Loss of self tolerance- both humoral (antibody mediated) and cellular mechanisms cause tissue damage
What main types of neoplasia trigger Immune mediated disease? (3)
Round cell tumour, Sarcomas, Hemangiosarcoma
What are sequestered antigens and what happens to these in immune mediated disease?
Cells that are isolated from the circulation of the blood and lymph & not in contact with the cells of the immune system- in immune mediated disease they are suddenly recognised as foreign and attacked
How does Molecular Mimicry initiate an auto immune response?
Sequence similarities between foreign peptides and self-peptides result in the cross-activation of autoreactive T or B cells
Why does Polyclonal activation of B Cells lead to Auto Immune Disorders?
It increases B-cell proliferation meaning enhanced antibody production and circulating immune complexes so causes bystander T-cell activation, where enhanced cytokine production induces autoreactive T cells
What is Heptenisation of Foreign Material?
Foreign material binds to a small molecule that normally exists in the body- this makes it larger, and unrecognisable to the immune system that then destroys it and everything it has bound to
What role does infection play in the trigger of Auto Immune Disease? (4)
- Breakdown of vascular or cellular barriers allowing exposure to self antigens
- Infection promotes cell death, causing inflammation and then activating immune cells
- Polyclonal activation of T cells
- Molecular Mimicry
How can Babesia spp lead to an Auto Immune disease?
Babesia spp binds to and invades RBC- our immune system goes to destroy Babesia thereby destroying RBC too and causing Haemolytic Anaemia
What can influence whether an animal develops an auto immune disease?
Genetics, Hormonal and Infectious response
Which group tend to be diagnosed with Non associative (idiopathic) immune mediated disease?
Juveniles
What are some clinical signs of an Immune mediated disease?
Lameness, Mucocutaneous lesions, Lethargy, weight loss, seizures, behavioural changes, pustules, cardiac arrhythmia
What may we see on a Complete Blood Count (CBC) test in a patient with an Immune Mediated Disease? (4)
Anaemia, Thrombocytopenia, Leucopenia, Coagulation Abnormalites
If we use biochemistry to diagnose an Immune Mediated Disease, what may we expect to see? (5)
Azotemia, Hypoalbuminaeria, Hyperbilirubinaemia, Hypweglobinulinaemia, Increased Creatine Kinase
In immune mediated disease, if we performed a Urinalysis what may you expect to see?
Proteinuria & Haematuria
In polysystemic immune mediated disease, what lesions are common and why?
Joint lesions & arthritis due to increased inflammatory processes
How can we detect a joint lesion caused by polysystemic immune mediated disease?
Take synovial fluid and look for increased WBC, increased neutrophils, increased protein content and decreased viscosity (watery fluid)
For suspected acute immune mediated haemolytic anaemia, what’s the first test we do to confirm this diagnosis?
In Saline Agglutination test
How does an In Saline Agglutination test work?
Erythrocytes agglutinate when Ig binds to their surface- in IMD with increased Ig in the blood, they agglutinate
What is true agglutination in relation to the In Saline Agglutination test?
true agglutination means the results are still positive (erythrocytes agglutinated) after 3 washing processes with NaCl
What does the Coombs test detect?
Antibodies associated with the surface of RBCS
How do we diagnose Acquired Myasthenia Gravis?
detection of nicotinic AChR autoAB by immunoprecipitation
How do we diagnose SLE (systemic lupus erythematosus?
Look at serum ANA (antinuclear antibodies) using an indirect immunofluorescence test
