Immune Mediated Disease

Question 1

What three underlying factors can trigger an immune mediated disease to develop?

Answer 1

Drug usage (that includes vaccines), Neoplasia or Infection

Question 2

What do we mean when we talk about a spectrum of immune mediated disease?

Answer 2

Immune mediated disease can be organ or non organ specific e.g. effecting a bunch of tissues vs effecting one receptor

Question 3

What goes wrong in an immune mediated disease?

Answer 3

The Immune system overreacts to normal tissue or harmless exogenous (self) proteins

Question 4

What is the one thing necessary to perpetuate the start of an immune mediated disease?

Answer 4

Loss of self tolerance- both humoral (antibody mediated) and cellular mechanisms cause tissue damage

Question 5

What main types of neoplasia trigger Immune mediated disease? (3)

Answer 5

Round cell tumour, Sarcomas, Hemangiosarcoma

Question 6

What are sequestered antigens and what happens to these in immune mediated disease?

Answer 6

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

Question 7

How does Molecular Mimicry initiate an auto immune response?

Answer 7

Sequence similarities between foreign peptides and self-peptides result in the cross-activation of autoreactive T or B cells

Question 8

Why does Polyclonal activation of B Cells lead to Auto Immune Disorders?

Answer 8

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

Question 9

What is Heptenisation of Foreign Material?

Answer 9

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

Question 10

What role does infection play in the trigger of Auto Immune Disease? (4)

Answer 10

• 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

Question 11

How can Babesia spp lead to an Auto Immune disease?

Answer 11

Babesia spp binds to and invades RBC- our immune system goes to destroy Babesia thereby destroying RBC too and causing Haemolytic Anaemia

Question 12

What can influence whether an animal develops an auto immune disease?

Answer 12

Genetics, Hormonal and Infectious response

Question 13

Which group tend to be diagnosed with Non associative (idiopathic) immune mediated disease?

Answer 13

Juveniles

Question 14

What are some clinical signs of an Immune mediated disease?

Answer 14

Lameness, Mucocutaneous lesions, Lethargy, weight loss, seizures, behavioural changes, pustules, cardiac arrhythmia

Question 15

What may we see on a Complete Blood Count (CBC) test in a patient with an Immune Mediated Disease? (4)

Answer 15

Anaemia, Thrombocytopenia, Leucopenia, Coagulation Abnormalites

Question 16

If we use biochemistry to diagnose an Immune Mediated Disease, what may we expect to see? (5)

Answer 16

Azotemia, Hypoalbuminaeria, Hyperbilirubinaemia, Hypweglobinulinaemia, Increased Creatine Kinase

Question 17

In immune mediated disease, if we performed a Urinalysis what may you expect to see?

Answer 17

Proteinuria & Haematuria

Question 18

In polysystemic immune mediated disease, what lesions are common and why?

Answer 18

Joint lesions & arthritis due to increased inflammatory processes

Question 19

How can we detect a joint lesion caused by polysystemic immune mediated disease?

Answer 19

Take synovial fluid and look for increased WBC, increased neutrophils, increased protein content and decreased viscosity (watery fluid)

Question 20

For suspected acute immune mediated haemolytic anaemia, what’s the first test we do to confirm this diagnosis?

Answer 20

In Saline Agglutination test

Question 21

How does an In Saline Agglutination test work?

Answer 21

Erythrocytes agglutinate when Ig binds to their surface- in IMD with increased Ig in the blood, they agglutinate

Question 22

What is true agglutination in relation to the In Saline Agglutination test?

Answer 22

true agglutination means the results are still positive (erythrocytes agglutinated) after 3 washing processes with NaCl

Question 23

What does the Coombs test detect?

Answer 23

Antibodies associated with the surface of RBCS

Question 24

How do we diagnose Acquired Myasthenia Gravis?

Answer 24

detection of nicotinic AChR autoAB by immunoprecipitation

Question 25

How do we diagnose SLE (systemic lupus erythematosus?

Answer 25

Look at serum ANA (antinuclear antibodies) using an indirect immunofluorescence test