Innate And Adaptive Immunity Practice Test

A pharmaceutical company is developing a new immunosuppressant that functions as an antagonist to the B7 molecule on antigen-presenting cells (APCs). The drug is intended to prevent the rejection of transplanted organs by modulating T-cell responses.

A 2-year-old boy presents with a history of recurrent severe bacterial infections of the sinuses and lungs, as well as an episode of Pneumocystis jirovecii pneumonia. Laboratory studies show markedly elevated serum IgM levels but almost undetectable levels of IgG, IgA, and IgE. T-cell and B-cell counts are normal.