Immune deficiencies

Question 1

Briefly describe the classification of primary immune deficiency disorders

Answer 1

Adaptive Immune Disorders
- Antibody deficiencies (B-cell dysfunction)
- Cellular immunodeficiencies (mainly T-cells)
Innate Immune Disorders
- Phagocyte defects
- Complement deficiencies
- Absence/polymorphisms in Pathogen Recognition Receptors

Question 2

What is SCID?

Answer 2

Severe Combined Immune Deficiency
- defect in pluripotent stem cells, lymphoid stem cells or mature T/Bcells
Requires intensive supportive therapy
Cured by bone marrow transplant only

Question 3

What is DiGeorge syndrome?

Answer 3

22q11 deletion syndrome

CATCH22 clinical features

Question 4

Give four diseases caused by phagocyte defects.

Answer 4

Congenital neutropenia (absence of neutrophils)
Chronic Granulomatous Disease (Impaired intracellular killing of pathogens)
Leukocyte adhesion defect (phagocytes cannot adhere to vascular endothelium)
Myeloperoxidase deficiency

Question 5

Which cell type is most often implicated in phagocyte deficiency diseases?

Answer 5

Neutrophils

Question 6

What are the most common clinical presentations of phagocyte disorders?

Answer 6

Pneumonia
Osteomyelitis
Skin/mucous membrane infection
Liver abscess
Suppurating lymph nodes

Question 7

What is hereditary angioedema?

Answer 7

Disease caused by C1-inhibitor deficiency/inactivity

- complement pathway is active even though there is no allergen

Question 8

What are the signs and symptoms of hereditary angioedema?

Answer 8

Recurrent episodes of swellings which are:

• painless
• non-pitting
• non-pruritic
• non-erythematous

Question 9

Describe the general therapies for treating immune-deficiency disorders

Answer 9

• Identification and treatment of any underlying causes
• Appropriate antimicrobial therapy for infectious complications
o Some cases may require prophylaxis in certain situations
• Avoid risks
o T-cell deficiency  avoid immunisation with live vaccines
o Cell-mediated defect  avoid blood transfusion
• Genetic counselling
• Prenatal diagnosis where possible

Question 10

Describe the specific therapeutic options for treating immune-deficiency disorders

Answer 10

•	Immunoglobulin replacement
o	Intravenous
o	Subcutaneous
•	Transplantation
o	Bone marrow  especially for SCID
o	Thymus
•	Gene therapy
•	(anti)cytokine therapy