BIOL 2050U Lecture Notes - Fc Receptor, Mecha, Lysosome
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INNATE IMMUNITY
rapid (minutes/hours), generalized response to injury
FEATURES:
primary response
shares effectors w/ adaptive immunity; stimulates adaptive immunity
recognizes MOLECULAR patters (as opposed to structural patterns)
INVARIANT receptor classes (as opposed to recombined)
appears in JAWED VERTEBRATES
TARGETS: PAMS (pathogen-associated molecular patterns)
invariant and specific to pathogen; necessary for pathogen survival
(ex/ dsRNA, LPS, mannoprotein, f-Met, etc.)
host has RECEPTORS: PRR’s (pattern recognition receptors)
germline encoded; not arranged
widely distributed (intracellular, cell surface, and secreted)
varied functions –
opsonization
phagocytosis
complement
cytokine release
apoptosis
TLR’s – TOLL LIKE RECEPTORS
transduce PAMP signal into effector cell
trigger at least 2 signal transduction cascades
MAPK
inflammatory
different TLR’s different responses
2 – recognizes yeast
4 – LPS
INNATE IMMUNE CELLS
NEUTROPHILS MACROPHAGES
short lived (days) long lived
kill bacteria kill bacteria AND regulate inflammation
ROI, degradative enzymes cytokine secretion
can present antigens
ROI and NO
both arise from MYELOID progenitor cells (which came from pluripotent hematopeoetic
stem cell)
NEUTROPHILS –
mature in bone marrow and released into blood
adhere/diapedese through tissue
kill pathogens by phagocytosis and use of ROS/degradative enyzmes
all activities are cytokine regulated
Defects:
NEUTROPENIA – fatal due to bacterial/fungal infection
Defects can occur in
adherence
chemotaxis
killing
MACROPHAGES –
can live in tissue for >1 month
interact w/ adaptive immune system
can remodel tissue
can kill pathogens