Immunodeficiency

Question 1

What does primary immunodeficiency commonly present as, and what are some other examples?

Answer 1

• As recurrent infection in young
• Also: - allergy
• autoimmunity
• cancer
• abnormal lymphocyte proliferation

Question 2

What sort of deficiencies can primary immunodeficiency present?

Answer 2

As B cell deficiencies, T cell deficiencies and innate immune deficiencies.

Question 3

What are the types of primary immunodeficiency?

Answer 3

1. Combined immunodeficiencies
2. Combined, with syndromic features
3. Antibody deficiencies
4. Immune disregulation
5. Phagocyte defects
6. Defects in innate immunity
7. Autoinflammatory disorders
8. Complement deficiencies
9. Phenocopies of PID

Question 4

What are secondary immunodeficiencies?

Answer 4

-Not genetic, are circumstantial
-Eg’s. HIV;depletion of CD4 helper T cells
Protein calorie malnutrition
Spleen removal
cancer metastases to bone marrow

Question 5

What is X-linked SCID?

Answer 5

Caused by mutations in cytokine receptors IL-2RY chain. T cells and NK cells fail, B cells normal BUT no help for efficient antibody responses.
So there is no common gamma chain.

Question 6

What is hyper IgM syndrome?

Answer 6

High IgM, low no. of other antibodies due to fault in class switching
The fault lies on the CD40L molecule on T cells.

Question 7

What is FOX NI Deficiency?

Answer 7

An example of combined immunodeficiency (with syndromic features).
No T cells, B cells normal but no help.
No hair and thymic epithelium fails to develop.
Therefore thymus fails to develop so no T cells.

Question 8

What is an eg of the congenital defects of phagocytes?

Answer 8

Defects of neutrophil function

Question 9

What is an eg of defects in innate immunity?

Answer 9

Myd 88 deficiency- bacterial infections

Chronic mucocutaneous candidiasis

Question 10

What is an eg of autoinflammatory disorders?

Answer 10

Defects affecting the inflammasome

Question 11

What are eg’s of antibody deficiencies?

Answer 11

• Brutons tyrosine kinase deficiency
• CD40L deficiency
• IgA deficiency

Question 12

What happens in brutons tyrosine kinase deficiency?

Answer 12

• Caused by mutation in bruton’s tyrosine kinase gene
• Prevents B cell development
• Results in low serum antibody levels

Question 13

What happens in IgA deficiency?

Answer 13

B cells unable to switch from producing IgM to IgA.

IgA needed to fight intestinal bacteria.

Question 14

What does lack of antibody lead to?

Answer 14

• Recurrent sepsis
• Bacterial infections, often in airways
• Chronic gastroenteritis
• Failure to thrive