Cells of Innate Immunity Flashcards
PAMPs
pathogen-associated molecular patterns. diverse mixture of molecules expressed by microbial invaders that can be recognized by the body as foreign.
DAMPs
damage-associated molecular patterns. molecules released from damaged cells, generate alarm signals
PRRs
Pattern-Recognition Receptors. PAMPs and DAMPs bind to them. They are found on sentinel cells located in blood, on cell surfaces, and within cells (either in endosomes or in cytoplasm)
Binding to pattern-recognition receptors
- triggers inflammation
- triggers interferon production
- triggers sickness behavior
- begins the adaptive immune process
TLRs
Toll-like receptors.
TLRs found on cell surfaces
detect microbial cell surface molecules. primarily directed against bacteria
TLRs found in intracellular vesicles
detect foreign nucleic acids. primarily directed against viruses
Leukocytes
WBC. originate from the hematopoietic cells in the bone marrow
Most common Leukocytes
- Neutrophils
- Lymphocytes
- Monocytes
- Eosinophils
- Basophils
Neutrophils
the first phagocytic cells to attack and destroy invading bacteria. Move rapidly but lack stamina. Simply destroy invaders but can cause collateral damage. Kill using reactive oxygen compounds and defensins. Rapidly mobilized from the bone marrow
Neutrophils Leaving blood vessels
in inflamed tissues the blood vessel walls are sticky. Neutrophils stick to vascular endothelium. Adherence is mediated by integrins and selectins
Mononuclear Phagocytes
arise primarily from the marrow and are released into the blood as monocytes. They may circulate for hours to a few days before entering the tissues and differentiating to become macrophages.
Granulocytes
have a segmented nucleus and are classified according to their staining characteristics as neutrophils, eosinophils, or basophils
Stages of Phagocytosis
- chemotaxis
- adherence
- ingestion
- destruction
Opsonization
bacteria coated by antibodies and/or complement bind to neutrophil receptors and are readily ingested
