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Old 06-13-2012
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Question A 4-year-old child has a history of recurrent sinopulmonary infections with...

A 4-year-old child has a history of recurrent sinopulmonary infections with Staphylococcus aureus and Streptococus pneumoniae since the age of 17 months. He also developed an arthritis that cleared with immunoglobulin therapy. On physical examination, he is at 30th percentile for height and weight. His temperature is 37.9 C. There is no lymphadenopathy, and lymph nodes are difficult to palpate. There is no hepatosplenomegaly. Laboratory studies show total serum protein of 5.1 g/dl and albumin 4.6 g/dl. A lymph node biopsy specimen shows lymph nodes with rudimentary germinal centers. Over the next 10 years, the child develops arthralgias and erythematous skin rashes and has a positive ANA result. Which of the following types of cells has most likely failed to differentiate to produce this patient's disease?

A) CD4+ lymphocytes
B) CD8+ lymphocytes
C) Follicular dentritic cells
D) Monocyte
E) Natural killer cells
F) Pre-B cell
G) Stem cell
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Old 06-13-2012
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I would go with F
immunodeficiencies increases the risk for autoimmun disease, in this case i think its a juvenile arthritis,
agammaglobulinemia (0.7g/dl of proteins other than albumin), poor germinal centers indicate B cell disorder.
Bruton's ?
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Old 06-14-2012
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Quote:
Originally Posted by Casandra View Post
A 4-year-old child has a history of recurrent sinopulmonary infections with Staphylococcus aureus and Streptococus pneumoniae since the age of 17 months. He also developed an arthritis that cleared with immunoglobulin therapy. On physical examination, he is at 30th percentile for height and weight. His temperature is 37.9 C. There is no lymphadenopathy, and lymph nodes are difficult to palpate. There is no hepatosplenomegaly. Laboratory studies show total serum protein of 5.1 g/dl and albumin 4.6 g/dl. A lymph node biopsy specimen shows lymph nodes with rudimentary germinal centers. Over the next 10 years, the child develops arthralgias and erythematous skin rashes and has a positive ANA result. Which of the following types of cells has most likely failed to differentiate to produce this patient's disease?

A) CD4+ lymphocytes
B) CD8+ lymphocytes
C) Follicular dentritic cells
D) Monocyte
E) Natural killer cells
F) Pre-B cell
G) Stem cell
Probably from specific Ig deficiency resulting recurrent attack of sinopulmonary infections with Staphylococcus aureus and Streptococus pneumoniae.
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Old 06-14-2012
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F.......brutons may be....
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Old 06-14-2012
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F...i'm thinking!!!
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Old 06-14-2012
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Default correct answer :)

Correct answer is F) Pre-B cell

This child has features of X-linked agammaglobulinemia of Bruton. In this condition, B-cell maturation stops after the rearrangement of heavy-chain genes, and light chains are not produced. Complete immunoglobulin molecules with heavy and light chains are not assembled and transported to the cell membrane. The lack of immunoglobulins predisposes the child to recurrent bacterial infections. Because T-cell function remains intact, viral, fungal, and protozoal infections are uncommon. CD$ and CD8 lymphocytes differentiate from precursors in the thymus, which is not affected by BTK gene mutation that gives rise to Bruton agammaglobulinemia.
Follicular dendritic cells are a form of antigen presenting cell that is not affected by B-cell and T-cell disorders.
Monocytes may leave the circulation to become tissue macrophages, a process not dependent on B-cell maturation.
Natural killer (NK) cells are a part of innate immune system and respond to antibody coating abnormal cells - a process diminished by reduced antibody production- but the NK cells themselves are not directly affected by lack of immunoglobulin.
Lack of stem cell differentiation is incompatible with life.

Bruton's agammaglobulinemia sum up:
why? mutation in BTK gene (X-linked recessive)
what? failure of pre-B cells to become mature B-cells (antibody production)
so? recurrent sinopulmonary infections
when? after 6th month of age (till 6th month baby is protected by mother's antibodies)
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