In this short tutorial i have described the the basics of process of leukocyte activation and described PHAGOCYTOSIS in detail.. Visit ilovepathology.com/ for more topics in Pathology!
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What NEXT? After recruitment of leukocytes
To recognize the microbes/necrotic cells/foreign bodies
Activation of Leukocytes
Phagocytosis & intracellular Killing
What NEXT? After recruitment of leukocytes
To recognize the microbes/necrotic cells/foreign bodies
Activation of Leukocytes
Phagocytosis & Killing
How these stimuli are recognized by the PHAGOCYTES?
PHAGOCYTIC RECEPTORS
Mannose receptors Bind terminal mannose & fucose residues of glycoproteins & GlycolipidsThese sugars are found in walls of microbesNot found in mammalian cells
Scavenger receptors Bind modified LDL particles
Opsonin receptors
Recognize opsonins
Opsonin: antibody that renders bacteria and other cells susceptible to phagocytosis, IgG, C3b, Mannose binding lectin
What happens when leukocytes are activated?
Phagocytosis
Destruction of Phagocytosed Microbes & dead cells;By Reactive oxygen & nitrogen species& lysosomal enzymes
Destruction of extracellular microbes & dead cells;By forming extracellular “traps”
Production of chemical mediators;Amplify inflammation
Phagocytosis A process
Which involves the recognition , engulfment and digestion of
Microbes, dead cells an foreign bodies
Greek word
Phagein, meaning "to devour" kytos, meaning "cell", and -osis, meaning "process")
Also referred to as “cell eating”
kILLING: Occur in neutrophils and Macrophages
By
Reactive oxygen species
Reactive nitrogen species
Lysosomal enzymes
The killing occur in phagolysosomes thus avoiding damage to cell’s cytoplasm and nucleus
REACTIVE OXYGEN SPECIES
Produced by NADPH Oxidase (Phagocyte oxidase)
Phagocyte oxidase is present in the membrane of phagosome and lysosome
Thus ROS, can be produced in lysosome and Phagolysosome