Immunology 2

Question 1

Major consequence of immunodeficiency

Answer 1

Increased susceptibility to infection
Susceptible to cancer
Increased risk of autoimmunity

Question 2

Define primary immunodeficiency

Answer 2

Genetic, congenital disorders
When part of the immune system is either missing or functioning abnormally
Can be caused by mutations or autoimmunity

Question 3

For primary immunodeficiency where can the abnormality occur?

Answer 3

• components of the innate immune system eg Chronic granulomatous disease affects the phagocytes
• stages of lymphocyte development

-responses of mature lymphocytes to antigenic stimulation
Eg hyper-IgM syndromes

Question 4

If you are B cell deficient what kind of infection are you susceptible to?

Answer 4

Pyogenic bacteria (eg otitis, pneumonia, meningitis, osteomyelitis),
Enteric bacteria
Viruses
Parasites

Question 5

If you are T cell deficient what kind of infection are you susceptible to?

Answer 5

Pneumocystis jiroveci,
Viruses,
Atypical mycobacteria,
Fungi

Question 6

If disease presents with encapsulated bacteria what is the likely immunodeficiency

Answer 6

B-cell defects

Complement defects

Question 7

If disease presents with neisseria what is the likely immunodeficiency

Answer 7

Complement defects

Question 8

If disease presents with:
-Invasive fungi
Staphylococcus,
Gram negative bacteria

what is the likely immunodeficiency

Answer 8

phagocyte defects

Question 9

If disease presents with:

• low-virulence mycobacteria
• cytomegalovirus
• EBV/ lymphoma
• HHV8/ Kaposi sarcoma
• pneumocystis
• TB
• Candida
• Reactivation of herpes simplex and herpes zoster

what is the likely immunodeficiency

Answer 9

T-cell defects

More intracellular pathogens

Question 10

Causes of primary immunodeficiency?

Answer 10

Mutations (permanent alteration in the DNA sequence) 
Polymorphism (involves one of two variants of a DNA sequence)
Polygenic disorders (disorders caused by the combined action of more than one gene)

Question 11

What is a SCID

Answer 11

Severe Combined ImmunoDefiency
Group of disorders that affect both T and B cells

Can be autosomally inherited or X-linked

Question 12

Treatment for SCID

Answer 12

Immediate Stem cell transplant
Or gene therapy

Avoid live vaccines until treatemtn
Prophylaxis against pneumocystis jiroveci

Question 13

Example of a SCID

Answer 13

DiGeorge Syndrome (22q11 deletion)

Bare lymphocyte syndrome (defects in transcription factors)

MHC class I deficiency (mutations in TAP1, TAP2 and TAPASIN)

Question 14

Common polygenic disorders that affect antibody production

Answer 14

Common Variable Immunodeficiency (CVID),
IgA deficiency,
Specific antibody deficiency

Question 15

Describe CVID

Answer 15

Common Variable ImmunoDeficiency
Most common primary immunodeficiency requiring treatment

Patients have low levels of total IgG
IgA, IgM and B and T cell levels are variable

Causes recurrent respiratory tract infection
Can also cause infections of the gut, skin, nervous system

Suggestive autosomal-recessive inheritance

Question 16

Name an example of primary immunodeficiencies caused by autoimmunity

Answer 16

Autoimmune Polyendocrinopathy Candidiasis Ectodermal Dysplasia (APCED)

Have a defect in central tolerance and experience many types of autoimmunity

normally frequently experience severe recurrent Canadia infection
(Can’t fight as body produces autoantibodies against IL-17)

Some produce autoantibodies against IFN-y (these patients have problems with mycobacteria please infection)

Question 17

Clinical presentation and history of SCID

Answer 17

Develop infection in first week of life,
Unusual or recurrent infection,
Diarrhoea,
Unusual rashes

Low lymphocyte count

History:

• FH of neonatal death
• FH of consanguinity

Question 18

Treatment of primary immunodeficiency

Answer 18

Prophylactic antibiotics

Immunoglobulin replacement therapy

Question 19

In primary immunodeficiency what criteria must be met for gene therapy

Answer 19

Genetic mutation must be identified,
Transferred gene must confer a proliferation or survival advantage
Must not cause malignancy

Question 20

What is secondary immunodeficiency

Answer 20

Synthesis of key components is suppressed (eg bone marrow infiltration or infection) or their loss is accelerated