UKMLA PLAB AMC USMLE Prometric MCQ

Question Number 0813

Question:
A young mother brings her 2 year old son to the doctor and comments that he is always sick. Upon further questioning, his mother is adament he was healthy until he was about 9 months old when the problems began. He has had recurrent respiratory infections due to pneumoccocus and Haemophilus influenzae. He also has recurrent bouts of ear infections and pharyngitis. His serum concentrations of immunoglobulins are in the third percentile. He is eventually diagnosed with X-linked agammaglobulinemia of Bruton. This is a problem with B lymphocytes. Which of the following is a true feature of B lymphocytes?

a) their immunocompetence is gained in the thymus
b) they are found in the deep cortical region of lymph nodes
c) presence of surface immunoglobuin
d) forms rosette with sheep red blood cells
e) they make up 70% of the lymphocytes in the circulation