X-linked Agammaglobulinemia Flashcards Preview

Medical Immunology Bios 443/843 > X-linked Agammaglobulinemia > Flashcards

Flashcards in X-linked Agammaglobulinemia Deck (7):
1

Why is the presence of this disorder on the X chromosome initially confusing?

Because genes encoding the structure of immunoglobulin polypeptide chains are encoded on autosomal chromosomes and not on the X chromosome.

2

Does x-linked agammaglobulinemia effect T-cell production?

No. Males with x-linked agammaglobulinemia have normal T cell levels. People with the condition have the ability to combat viral infections and infections with intracellular organisms, but are less adept at combating extracellular microbes.

3

What type of bacteria are the major cause of infection for people with x-linked agammaglobulinemia?

pyogenic bacteria (Pus forming)

4

Why are recurrent infections with pyogenic bacteria a source of concern?

pyogenic bacteria, and host phagocytes, release proteolytic enzymes (elastase) that can cause damage to tissues. The airway of the lungs are a major recipient of harm. chronic inflammation occurs with recurring infections with pyogenic bacteria, and patients have a risk of death associated with chronic lung disease.

5

What is the genetic basis of x-linked agammaglobulinemia?

1) gene defect in the long arm of the X chromosome at Xq22. 2) Actual gene BTK.

6

Why is BTK important for the functioning of B cells?

1) BTK tyrosine kinase found in pre-B cells, B cells, and neutrophils. 2) BTK is required to mediate survival and further differentiation of progenitor B cells, and survival of mature B cells.

7

What is the most important receptor in the phagocytosis of pyogenic bacteria?

iC3b. iC3b is produced when IgG2 antibodies coat the surface of a pathogen; IgG2 recruits and deposits C3b on the bacterial surface; C3b is cleaved by factors H and I. iC3B works best when it associated with Fc receptors for IgG1 antibodies.

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