Monocytes

Definition

Monocytes are a type of white blood cell that plays a crucial role in the innate immune system by differentiating into macrophages and dendritic cells upon entering tissues. They are essential for phagocytosis and pathogen recognition.

5 Must Know Facts For Your Next Test

1. Monocytes circulate in the bloodstream and make up about 2-8% of the total leukocyte count.
2. Upon migrating into tissues, monocytes differentiate into macrophages or dendritic cells based on the signals they receive.
3. Macrophages derived from monocytes are key players in phagocytosis, engulfing and digesting pathogens and cellular debris.
4. Monocytes express receptors like Toll-like receptors (TLRs) that recognize pathogen-associated molecular patterns (PAMPs).
5. They release cytokines that help coordinate the immune response, recruiting other immune cells to infection sites.

Review Questions

• What percentage of white blood cells do monocytes typically constitute?
• Into what two cell types can monocytes differentiate once they enter tissues?
• What role do Toll-like receptors play in the function of monocytes?

Related terms

Macrophage: A large phagocytic cell derived from monocytes that engulfs pathogens and dead cells.

Dendritic Cell: An antigen-presenting cell derived from monocytes that activates T-cells.

Phagocytosis:

The process by which certain living cells called phagocytes ingest or engulf other cells or particles.