Immune-mediated disease

Question 1

What are the different types of immune-mediated disease

Answer 1

hypersensitivity (allergic disease)
autoimmune diseases
immune system neoplasia
immunodeficiency diseases/ disorders

Question 2

what are the 2 categories of immune-mediated disease

Answer 2

primary (idiopathic)
secondary

Question 3

what causes a primary immune mediated disease

Answer 3

caused by underlying dysfunction or imbalance in the immune system
diagnosis by exclusion of causes of secondary disease

Question 4

what causes secondary immune mediated disease

Answer 4

infection
inflammatory disease
drugs
neoplasia
environment

Question 5

define immunodeficiency

Answer 5

a functional problem with the immune system

Question 6

what is typically seen with a primary immunodeficiency

Answer 6

repeated infections in young aniamls

Question 7

which factors is most relevant in predisposing a dog to a primary immunodeficiency disorder

Answer 7

genetic

Question 8

What is the most sensitive test for a diagnosis of immune mediated haemolytic anaemia

Answer 8

Coombs test/ direct antiglobulin test (DAT)

Question 9

what 3 molecules can antibodies bind to causing IMHA/IMTP

Answer 9

normal self antigen
infectious agents bound to cell surface
non-biologic Ag bound to cell surface

Question 10

List 6 reasons RBCs may be destroyed in IMHA

Answer 10

idiopathic
alloantibody present
autoantibody to RBC membrane antigen
cross-reacting antibody against infectious agent
antibody against drug adherent to RBC
drug or infection modifies RBC antigen

Question 11

What is the trigger for primary IMHA

Answer 11

no known causative trigger

Question 12

what breeds of dog tend to get primary IMHA

Answer 12

cocker spaniels
springers spaniels
poodles

Question 13

what type of IMHA to cats tend to get

Answer 13

secondary- usually due to infections (e.g. mycoplasma)

Question 14

what type of IMHA do dogs tend to get

Answer 14

primary

Question 15

what is intra vascular haemolysis

Answer 15

direct lysis of RBCs due to antibody binding and complement activation –> releases free haemoglobin in to plasma

Question 16

what do you tend to see with intravascular haemolysis

Answer 16

red/pink plasma
red/pink urine

Question 17

what is extravascular haemolysis

Answer 17

antibody binding to RBCs stimulates phagocytosis by mononuclear cells in the liver and spleen
haemoglobin metabolised by liver –> haemoglobin processing produces bilirubin

Question 18

how can you tell the difference between intravascular and extravascular IMHA

Answer 18

intravascular will have haemoglobinaemia and haemoglobinuria.
extravascular will have billirubinaemia and billirubinuria

Question 19

which type of IMHA forms spherocytes

Answer 19

extravascular haemolysis

Question 20

what do you tend to see with extra vascular haemolysis

Answer 20

jaundice
because the haemoglobin processing produces bilirubin

Question 21

what do we seen on haematology in IMHA

Answer 21

PCV low
regenerative anaemia
neutrophilia
spherocytes may be present

Question 21

Describe how to test for IMHA

Answer 21

Saline agglutination test or coombes test

Question 22

describe how to perform a saline agglutination test

Answer 22

4 drops of saline to 1 drop EDTA blood and mix by rocking the slide
- agglutination occurs if IMHA is present

Question 23

Describe the coombes test

Answer 23

identifies antibodies on the surface of the patient RBCs- add a load more antiserum antibodies to the sample to test if the RBCs stick

Question 24

what is a spherocyte

Answer 24

small densely staining spherical RBCs, lack central pallor indicator of immune-mediated haemolytic anaemia in dogs

Question 25

what biochemistry results might you see with IMHA

Answer 25

raised liver enzymes - ALT and ALP high billirubin and a low PCV bilirubinaemia or haemoglobinaemia

Question 26

what urinalysis results might you see with IMHA

Answer 26

bilirubinuria or haemoglobinuria

Question 27

what infectious diseases should you screen for in IMHA patients

Answer 27

CATS- mycoplasma haemofelis DOGS- babesia

Question 28

Describe how IMHA is treated

Answer 28

treat the underlying trigger where possible- antibiotics? Immunosuppression- glucocorticoids

Question 29

what adjuvant therapy can you give with glucocorticoids in IMHA

Answer 29

azathioprine Mycophenolate Mofetil cyclosporin leflunomide

Question 30

what is primary IMTP

Answer 30

autoimmune disorder with production of antibodies directed against normal platelet antigens

Question 31

What is secondary IMTP

Answer 31

antibodies target nonself antigens absorbed onto the surface of platelets or immune complexes bound to platelet surfaces associated with: infection, drugs, neoplasia

Question 32

list the clinical signs of IMTP

Answer 32

petechiae, echymoses, haematomas (bleeding in subcut tissues and skin) epistaxis gingival bleeding melaena/ haematochezia haematuria retinal haemorrhage

Question 33

List the lab findings seen in IMTP

Answer 33

low platelet count- make sure to check smear +/- anaemia

Question 34

what disease should you screen for in IMTP

Answer 34

ehrlichiosis rocky mountain spotted fever anaplasmosis histoplasmosis leishmaniasis distemper

Question 35

Describe how to treat IMTP

Answer 35

immunosuppression- prednisolone initially transfusion

Question 36

what are 3 indications to transfuse

Answer 36

rapidly falling PCV clinical signs- MOST IMPORTANT (tachycardia, poor pulse, weakness, tachypnoea, collapse) PCV <20% in dogs PCV<15% in cats

Question 37

why do we have to be very careful when treating for IMHA

Answer 37

it can lead to pulmonary thromboembolism - we should therefore provide a thromboprophylactic therapy as well

Question 38

what is an autoimmune disease

Answer 38

failure of self tolerance- rare influenced by: age, hormones, genetics, environment