Which cells differentiate into plasma cells that secrete antibodies?

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

Answer: (C)

B lymphocytes differentiate into plasma cells that secrete antibodies. When a B cell encounters its specific antigen and receives help from helper T cells, it activates, proliferates, and becomes either memory B cells or antibody-secreting plasma cells. Plasma cells are specialized for producing large amounts of antibodies, which then circulate to recognize and neutralize pathogens. The other cells listed don’t form antibodies: macrophages and neutrophils are phagocytes that ingest microbes, erythrocytes carry oxygen and don’t produce antibodies. Although lymphocytes include T and B cells, only the B cell lineage turns into antibody-secreting plasma cells.