Macrophages

Definition

Macrophages are large phagocytic cells derived from monocytes that play a crucial role in both innate and adaptive immunity. They engulf and digest pathogens, dead cells, and cellular debris.

5 Must Know Facts For Your Next Test

1. Macrophages can present antigens to T cells, linking innate and adaptive immune responses.
2. They release cytokines that modulate immune responses and inflammation.
3. Macrophages are found in virtually all tissues, acting as sentinels against infection.
4. They recognize pathogens through pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs).
5. Activated macrophages can differentiate into M1 (pro-inflammatory) or M2 (anti-inflammatory) phenotypes depending on the signals they receive.

Review Questions

• What roles do macrophages play in linking innate and adaptive immunity?
• How do macrophages recognize pathogens?
• What is the significance of macrophage polarization into M1 and M2 phenotypes?

Related terms

Phagocytosis:

The process by which a cell engulfs particles such as bacteria or cellular debris.

Antigen-Presenting Cells (APCs):

Cells that display antigens to T cells, initiating an adaptive immune response.

Cytokines:

Signaling proteins released by cells that affect the behavior of other cells, particularly in immune responses.