Immunodeficiencies

Question 1

Define the term immunodeficiency

Answer 1

One or several parts of the immune system is dysfunctional

Question 2

What is a primary immunodeficiency?

Answer 2

Genetic/congenital and may also be hereditary

Question 3

What is a secondary immunodeficiency?

Answer 3

Occurs due to secondary factors e.g. drugs or infection

Question 4

What are the 4 main types of inherited defects?

Answer 4

• single gene
• multiple genes
• chromosomal
• mitochondrial

Question 5

What is an autosomal recessive genetic disease?

Answer 5

One gene copy inherited from the mother and one from the father
The problem allele is only dangerous when expressed in a homologous manner
When heterozygous the animal is a carrier but isn’t ill

Question 6

Why is an autosomal recessive genetic disease usually only expressed when 2 carriers reproduce?

Answer 6

Affected animals often do not get to breed as the outcome is often fatal to neonates

Question 7

What occurs in animals that are complement deficient?

Answer 7

C3 deficient so lack the crucial point at which all 3 pathways converge

Question 8

What is leukocyte adhesion deficiency?

Answer 8

Phagocyte deficiency caused by failure of granulocytes to leave blood and enter sites of infection

Question 9

What enables normal cell migration?

Answer 9

Increased expression of adhesion molecules due to cytokines

Question 10

Neutrophils express which integrin molecule which allows passage into tissues?

Answer 10

CD11b/18

Question 11

Why is CD11b/18 needed to enable passage into tissues?

Answer 11

It binds to ICAM-1 on vascular endothelium

Question 12

What is deficient in animals with leukocyte adhesion deficiency, what is the result of this?

Answer 12

Interferon CD11b/18 - so no cell adherence to blood vessel walls - inability to leave circulation

Question 13

What result on a blood test would be indicative of leukocyte adhesion deficiency?

Answer 13

Very high WBC count because neutrophils fail to emigrate into tissues

Question 14

What protein mutations occur in CLAD and BLAD?

Answer 14

CLAD = cysteine changes to serine
BLAD = single aa change

Question 15

Describe equine severe combined immunodeficiency

Answer 15

• Defect prevents DNA repair so they fail to form functional antigen binding regions
• No functional T or B lymphocytes
• Foals sicken after MDA have gone from circulation

Question 16

Describe canine severe combined immunodeficiency

Answer 16

• Thymus has low numbers of lymphocytes
• Low T-cell numbers in circulation, no IgG or IgA
• X-linked so only males can express the disease whilst females are carriers

Question 17

What are the most important secondary immunodeficiencies?

Answer 17

Retroviruses

Question 18

Describe the disease stages of feline immunodeficiency virus

Answer 18

• Fever
• Virus goes to lymph nodes
• Replicates in T-cells
• Bone marrow suppression
• Death