key term - Activated macrophages

Definition

Activated macrophages are immune cells that have been stimulated by cytokines to enhance their phagocytic, antimicrobial, and antigen-presenting capabilities. These cells play a critical role in the body's defense mechanisms against pathogens and in inflammatory responses.

5 Must Know Facts For Your Next Test

1. Activated macrophages produce higher levels of reactive oxygen species (ROS) and nitric oxide (NO) to kill pathogens.
2. They secrete pro-inflammatory cytokines such as TNF-alpha, IL-1, and IL-6.
3. Activation typically occurs through exposure to interferon-gamma (IFN-γ) or microbial products like lipopolysaccharides (LPS).
4. They present antigens on MHC class II molecules to helper T cells, aiding in the adaptive immune response.
5. Chronic activation of macrophages can contribute to tissue damage and is implicated in various autoimmune diseases.

Review Questions

Related terms

Cytokines:

Signaling proteins that regulate immunity, inflammation, and hematopoiesis.

Phagocytosis:

The process by which cells engulf and digest pathogens or particles.

Antigen-Presenting Cells (APCs):

Cells that display antigens on their surface for recognition by T-cells; includes macrophages, dendritic cells, and B-cells.