Which of these is not a cell of the macrophage system?

Options

A. Kupffer cell
B. osteoclasts
C. Langerthans cells
D. astrocyte

Answer

To determine which of the listed cells is not part of the macrophage system, we can analyze each option:

1. **Kupfer Cell**: These are specialized macrophages located in the liver. They are part of the mononuclear phagocyte system, which includes all macrophages.

2. **Osteoclast**: These are cells that break down bone tissue and are also derived from the mononuclear phagocyte system. They play a role in bone remodeling and are considered part of the macrophage lineage.

3. **Langerhans Cell**: These are dendritic cells found in the skin and are also part of the mononuclear phagocyte system. They function in the immune response by presenting antigens.

4. **Astrocyte**: These are star-shaped glial cells in the brain and spinal cord. They are not part of the macrophage system; instead, they support neurons and maintain the blood-brain barrier.

Based on this analysis, the answer to the question is:

**Answer: Astrocyte is not a cell of the macrophage system.**