Filgrastim primarily stimulates production of which cells?

• A. Lymphocytes
• B. Platelets
• C. Erythrocytes
• D. Neutrophils

Answer: (D)

Filgrastim is a granulocyte colony-stimulating factor that acts on bone marrow progenitors to boost production of neutrophils. It binds to receptors on myeloid precursors, promoting their proliferation and differentiation into neutrophils and increasing their release into the bloodstream. This makes neutrophils the cells most increased by filgrastim, which is why it’s used to prevent infections in neutropenic patients, such as after chemotherapy. Lymphocytes come from a different lineage and aren’t the primary target, while platelets and red blood cells arise from other lineages (megakaryocytes and erythroid precursors, respectively) and aren’t the main effect of this treatment.