X-linked Agammaglobulinemia Flashcards
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.
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.
What type of bacteria are the major cause of infection for people with x-linked agammaglobulinemia?
pyogenic bacteria (Pus forming)
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.
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.
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.
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.
