Immunology 3: Innate Immunity

Neutrophils

Do neutrophils or macrophages have a higher phagocytic capacity?

Pathogen-associated molecular patterns (PAMPs)

Molecules conserved within a class of microbes but absent in the host

Endosomes

Membrane-bound vesicles in eukaryotic cells that sort and transport internalized molecules

Macrophages, neutrophils, dendritic cells

Phagocytic receptors

Macrophages, neutrophils, dendritic cells, NK cells, mast cells, eosinophils, basophils

Signaling receptors (cytokine production)

Cytokines

Small secreted proteins that act on cells

Tumor necrosis factor-alpha (TNF-alpha)

Increase vascular permeability

Activate vascular endothelial cells

Interleukin-1-beta (IL-1-beta)

Activate vascular endothelial cells

Activate lymphocytes

Interleukin-6 (IL-6)

Activate lymphocytes

Make heat and raise tissue temperature

Interleukin-12 (IL-12)

Induce IFN-gamma-producing CD4+ T (Th1) cells and cytotoxic CD8+ T lymphocytes (CTL)

CXCL8 (IL-8)

Chemokine

Recruit neutrophils from the blood to the infected tissue

Chemokine

Cytokines that cause chemotaxis

Rolling

Leukocytes ___ on vascular endothelial cells

Adhesion

Chemokines cause leukocytes to adhere firmly to the endothelial cells

Transmigration

Leukocytes cross the blood vessel wall and migrate to the site of inflammation

Opsonin

Makes bacteria easier for cells to eat

Dendritic cells

Most effective antigen-presenting cells

Macrophages

Second most effective antigen-presenting cells

B-cells

Third most effective antigen-presenting cells

Antigen, costimulatory molecules, cytokine

Three signals required for T-cell activation