Kupffer cells in the liver are a type of which cell?

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

Answer: (A)

Kupffer cells are specialized phagocytes that live in the liver; they are resident macrophages within the sinusoids. As part of the reticuloendothelial system, they originate from monocytes and are responsible for clearing bacteria and debris from portal blood, recycling iron from old red blood cells, and modulating immune responses by secreting cytokines and presenting antigens. This distinguishes them from neutrophils, which are circulating first responders in acute inflammation; erythrocytes, which are red blood cells carrying oxygen; and fibroblasts, which synthesize connective tissue. So the best description is that Kupffer cells are macrophages.