Q.69 Resident macrophages of ____ are called Kupffer cells.
(A) brain
(B) liver
(C) lung
(D) kidney

This article breaks down a key multiple-choice question (MCQ) on Kupffer cells, specialized resident macrophages crucial in immunology and histology. Ideal for biology students, NEET aspirants, and researchers studying macrophage functions in organs.

Kupffer cells are star-shaped resident macrophages lining the sinusoids of the liver, playing vital roles in phagocytosis, iron recycling, and immune surveillance. Named after Karl Wilhelm von Kupffer, they filter bloodborne pathogens and debris, making the liver a frontline defense organ.

Correct Answer: (B) liver

Kupffer cells exclusively reside in the liver’s sinusoidal endothelium. They constitute about 80-90% of the body’s fixed macrophages, efficiently clearing bacteria, old red blood cells, and toxins from portal blood.

Why Not the Other Options? Detailed Breakdown

Each organ hosts unique resident macrophages, adapted to local environments. Here’s why the alternatives don’t fit:

• (A) Brain: Microglia
  Microglia are the brain’s resident macrophages, derived from yolk sac progenitors. They monitor synapses, prune neurons during development, and respond to injury or infection. Unlike Kupffer cells, microglia rarely divide and express CX3CR1 markers.

• (C) Lung: Alveolar Macrophages
  Also called dust cells, alveolar macrophages patrol lung alveoli, engulfing inhaled particles, surfactant, and microbes. They produce cytokines during inflammation but differ from Kupffer cells in surfactant handling and location (air-liquid interface vs. blood sinusoids).

• (D) Kidney: Mesangial Cells (with Macrophage-Like Functions)
  Kidney mesangial cells provide structural support and phagocytic activity in glomeruli, but true resident macrophages are interstitial macrophages. Neither is termed Kupffer cells; they focus on immune regulation and waste filtration, not blood clearance like in the liver.

Kupffer Cells in Context: Functions and Significance

These macrophages express scavenger receptors (e.g., SR-A, CD163) for efficient uptake. In pathology, they contribute to liver diseases like fibrosis or alcoholic hepatitis via cytokine release (TNF-α, IL-6). Research highlights their role in nanoparticle clearance and gene therapy vectors.

For exams, remember: Kupffer cells = liver’s gatekeepers.