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Innate Immunity: Lecture 3 (Chemotaxis (Chemotactic factors (chemokins…
Innate Immunity: Lecture 3
Chemotaxis
the movement of a cell either toward or away from a chemical stimulus
positive chemotaxis involves use of psuedopods to crawl toward microorganisms at the infection site
Chemicals are microbial secretions, parts of microbial cells, damaged tissues and wbc's, and chemotactic factors
Chemotactic factors
defensins, peptides, and chemokins
chemokins
released by leukocytes already at infection site
Adhesion
after arriving at infection site phagocytes attach themselves to microorganisms through binding
will bind complimentary chemicals
found on the membranes of cells
also called attachment
Ingestion
phagocytes will extend pseudopods to surround the microbe
the microbe will be incorporated as the pseudopods fuse to form a vesicle called a phagosome
Maturation and Killing
a lysosome adds chemicals to maturing phagosome and will now become a phagolysosome
Phagolysosome have an antimicrobial substance that are highly reactive, toxins that forms of oxygen and in a pH of 5.5 environment
The environment and the 30 or so different enzymes end up destroying engulfed microbes
most die within 30 minutes of phagolysosome formation; do have virulence factors
Elimination
Digestion is not always complete
this causes phagocytes to eliminate remnants of microorganisms
eliminate by exocytosis