66 thymus is markedly hypoplastic - okt3

[ArchivalUser]

An 11-month-old infant has had upper and lower respiratory tract infections almost continuously since the time of birth, with organisms including Pneumocystis carinii (jiroveci) and Pseudomonas aeruginosa identified. The baby also has oropharyngeal candidiasis. The baby succumbs to a cytomegalovirus pneumonitis. At autopsy, the thymus is markedly hypoplastic, and lymph nodes throughout the body are small, with absent germinal centers on microscopic examination. Which of the following mechanisms is most likely to explain these findings?

A Adenosine deaminase deficiency

B Failure of B cells to become plasma cells

C Human immunodeficiency virus infection

D Autoantibodies to both T and B lymphocytes

E Failure of development of 3rd and 4th pharyngeal pouches

[ArchivalUser]

ee

[ArchivalUser]

A?

[ArchivalUser]

A) CORRECT. Severe combined immunodeficiency (SCID) may be due to adenosine deaminase deficiency in about half of cases. This disorder leads to malfunction of both humoral (B-cell) and cell-mediated (T-cell) immunity. Viral, fungal, and bacterial infections occur frequently in the first year of life.

[ArchivalUser]

agree with SCID ( ADA deficiency) but what about HIV? do you have any explication OKT3? thanks a lot bro for your help.

[ArchivalUser]

Sorry bro, I was away

© Incorrect. HIV infection could lead to multiple opportunistic infections but would not explain the thymic hypoplasia.

B) Incorrect. The findings with common variable immunodeficiency resemble those of X-linked agammaglobulinemia, but have their onset in late teenage years. Giardiasis is common.

(D) Incorrect. One mechanism for development of common variable immunodeficiency is autoantibody formation, with targeting of lymphocytes.

(E) Incorrect. Thymic hypoplasia in DiGeorge syndrome leads to T-cell deficiency with symptoms related to failure of cell-mediated immunity -- viral, fungal, and protozoal infections

[ArchivalUser]

thanks a lot OkT3 it s more clear now...