Immunodeficiency diseases

Question 1

Immunodeficieny occurs when what happens?

Answer 1

Generally when a component from our immune system is missing

Question 2

What are primary or congenital immunodeficiencies?

Answer 2

These are genetic defects that result in an increased susceptibility to infection
Often manifested in infancy and early childhood

Question 3

What are secondary or acquired immunodeficiencies?

Answer 3

These develop as a consequence of malnutrition, disseminated cancer, treatment with immunosuppressive drugs or infection of cells of the immune system

Question 4

T/F Toll-like receptors (TLRs) are conserved across widely diverse species? What does this mean?

Answer 4

True

This means that any loss of function mutation affecting a TLR has negative consequences for survival

Question 5

Why are TLRs so important for immune function?

Answer 5

The TLRs are what recognize all of the foreign bacteria and microbes that can invade the body

Question 6

What is the principal consequence of an immunodeficiency?

Answer 6

Increased susceptibility to infection

Question 7

What helps doctors predict the type of immunodeficiency?

Answer 7

The types of recurring infections that the patients presents with

Question 8

If you have deficient humoral immunity (B cell related), what are you more susceptible to?

Answer 8

Pyogenic bacteria

Question 9

Where are TLRs found?

Answer 9

On macrophages, dendritic cells and mast cells- the sentinels of the innate immune system

Question 10

If you have deficient cell-mediated immunity (T-cell related), what are you more susceptible to?

Answer 10

Viruses and other intracellular pathogens

Question 11

How is deficient humoral immunity treated?

Answer 11

It’s routine- prophylactic antibiotics and/or gamma-globulin therapy

Question 12

How is a deficient cell-mediated immunity treated?

Answer 12

Can’t really do anything- if you have this you die during childhood

Question 13

What is an example of a deficiency of humoral immunity?

Answer 13

X-linked Agammaglobulenemia (XLA)

Question 14

Tell me about XLA.

Answer 14

All antibody isotopes are very low- even IgM or IgD
Circulating B cells are usually absent
Fewer pre B-cells in bone marrow than normal
Lymph nodes and tonsils are small (due to lack of germinal centers)

Question 15

Why are XLA individuals fine for the first 6 months or so of life?

Answer 15

Because they are protected by passive immunity given them by their mother

Question 16

Tell me briefly about XLA.

Answer 16

Circulating B cells are usually absent

Pre-B cells are present in the bone marrow, but in reduced quantities

Question 17

What is the defect that causes XLA?

Answer 17

The Bruton Tyrosine Kinase that is important for pre-B cell expansion and maturation into Ig-expressing B cells doesn’t work

Question 18

What is the difference between X-linked immunodeficiency with hyper-IgM and XLA?

Answer 18

Well, X-linked immunodeficiency with hyper-IgM has low every other Ig but high counts IgM. Also, X-linked immunodeficiency with hyper-IgM has hyperplasia of the lymphoid tissues (enlarged)

Question 19

What is the defect in X-linked immunodeficiency with hyper-IgM?

Answer 19

Isotype switching doesn’t occur so an abundance of IgM results.
This happens because the CD40 ligand that is expressed on helper T cells is broken

Question 20

What is an example of cell-mediated immunodeficiency and what does it resemble?

Answer 20

DiGeorge’s syndrome and it resembles fetal alcohol syndrome

Question 21

What causes DiGeorge’s syndrome?

Answer 21

The thymus does not develop

Question 22

X-linked recessive severe combined immunodeficiency disease (XSCID) is rare and characterized by profound deficiencies in what?

Answer 22

T and B cell function (boy in the bubble)

Question 23

What are the current treatments of immunodeficiencies and what are their aims?

Answer 23

Aims to minimize and control infections and replace the defective or absent component of the immune system by adoptive transfer and/or transplantation.
The treatments are:
Passive immunization with pooled gamma globulin
Bone marrow transplants

Question 24

What is the result of aids?

Answer 24

Destruction of lymphoid tissue and depletion of CD4+ T cells