A 57-year-old woman comes to the emergency department due to cough and hemoptysis. The patient also reports several months of fatigue and joint pain. Physical examination is notable for crusting of the nasal mucosa, lung crackles, and scattered palpable purpura over the lower extremities. Chest x-ray reveals bilateral, diffuse alveolar infiltrates. Laboratory studies show normocytic anemia, red blood cell casts and protein in the urine, and positive c-ANCA. After a confirmatory biopsy, treatment with rituximab infusion is planned. This medication is most likely to improve this patient's condition via which of the following mechanisms?

Question

A 57-year-old woman comes to the emergency department due to cough and hemoptysis.  The patient also reports several months of fatigue and joint pain.  Physical examination is notable for crusting of the nasal mucosa, lung crackles, and scattered palpable purpura over the lower extremities.  Chest x-ray reveals bilateral, diffuse alveolar infiltrates.  Laboratory studies show normocytic anemia, red blood cell casts and protein in the urine, and positive c-ANCA.  After a confirmatory biopsy, treatment with rituximab infusion is planned.  This medication is most likely to improve this patient's condition via which of the following mechanisms?

Quizplus · Accepted Answer

Eductional Objective: Rituximab is a monoclonal antibody directed against CD20, a cell surface receptor on developing and mature B cells.  Binding of rituximab to CD20 results in B-cell cytotoxicity and phagocytosis, which reduces the B-cell population.  This reduces inflammatory symptoms in a wide range of rheumatologic diseases.

A 57-Year-Old Woman Comes to the Emergency Department Due to Cough