A 7-month-old Caucasian male presents with recurrent sinusitis and pharyngitis. The parents say that the child has had these symptoms multiple times in the past couple of months and a throat swab sample reveals the presence of Streptococcus pneumoniae. Upon workup for immunodeficiency it is noted that serum levels of immunoglobulins are extremely low but T-cell levels are normal. Which of the following molecules is present on the cells that this patient lacks?
ACD8
BCD3
CCD4
DNKG2D
ECD19
A 3-month-old boy presents to his pediatrician with persistent diarrhea, oral candidiasis, and signs and symptoms of respiratory syncytial virus (RSV) pneumonia. He is very lean with weight in the 10th percentile. His blood pressure is 105/64 mm Hg and heart rate is 84/min. He is being evaluated for an immunodeficiency. Laboratory results for HIV are negative by polymerase chain reaction (PCR). Which of the following is the most likely cause of this child’s presentation?
AGrossly reduced levels of B cells
BAn X-linked inheritance of HLA genes
CSelective IgA deficiency
DDefective T cell function
EDefective isotype switching
A father brings his 3-year-old son to the pediatrician because he is concerned about his health. He states that throughout his son's life he has had recurrent infections despite proper treatment and hygiene. Upon reviewing the patient's chart, the pediatrician notices that the child has been infected multiple times with S. aureus, Aspergillus, and E. coli. Which of the following would confirm the most likely cause of this patient's symptoms?
AIncreased IgM, Decreased IgG, IgA, and IgE
BNegative nitroblue-tetrazolium test
CPositive nitroblue-tetrazolium test
DNormal dihydrorhodamine (DHR) flow cytometry test
EIncreased IgE and IgA, Decreased IgM
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