Innate Immunity Flashcards
opsonization
the process of locating a microbe with molecules that can be recognized by receptors on phagocytes, which proceed to engulf and kill microbes
sites of microbial entry
epithelium of skin, GI tract, and respiratory tract
cells that show up at site of microbial entry
macrophages, dendritic cells, mast cells, phagocytes
plasma proteins
complement proteins that circulate in the blood promoting microbial destruction
cardinal feature of adaptive immunity
memory response, somatic rearrangement of gene segments during lymphocyte development leading to clonal expansion of B and T lymphocytes
innate microbial recognition
structures shared by classes of microbes not present on host cells are recognized
adaptive microbial recognition
lymphocytes express receptors (antibodies) on their cell surface that recognize specific antigens, activating phagocytosis, an innate property
PAMPs
microbial molecules shared by microbes of the same type that are not on normal host cells, that stimulate immune responses
examples of PAMPs
lipopolysaccharides (gram - bacteria), peptidoglycans (bacteria), terminal mannose residues (opportunistic infections), and unmethylated CG rich DNA (viruses)
DAMPs
damage-associated molecular patterns released from damaged or necrotic host cells present in injury, infarction, or infection
PRRs
pattern recognition receptors, recognize PAMPs and DAMPs, present on phagocytes, dendritic cells, and others
PRRs can be located in different places in the cell
cell surface to detect extracellular microbes, vesicles where microbes are ingested, and the cytosol to sense cytoplasmic microbes
Toll-Like Receptors are PRRs detecting microbial components located
extracellularly, recognizing proteins, lipids, and polysaccharides on cell surfaces, and in endosomes, recognizing nucleic acids
What do toll-like receptors do
activate transcription factors to stimulate the expression of genes encoding cytokines, enzymes and NF kappa B, which promotes other infection-fighting agents
what is the result of a defect in TLR signaling
recurrent and highly severe infections
which toll-like receptors are found extracellularly and what do they find
1,2,4,5,6 look for proteins, lipids, and polysaccharides on microbial membranes
which toll-like receptors are found intracellularly in endosomes and what do they find
3,7,8,9 look for nucleic acids, both single and double stranded RNA and CG rich DNA (viruses)
how do toll-like receptors signal inflammatory responses
engage with bacteria or virus on leucine-rich repeats, signaling domain recruits transcription factors NF kappa B and interferon regulatory factors, which lead to increased expression of inflammatory cells and antiviral cells
what does NF kappa B do
transcription factor, increases expression of cytokines, adhesion molecules, and costimulators, leading to acute inflammation and the stimulation of adaptive immunity
what do interferon regulatory factors do
transcription factor, increases expression of type 1 interferons IFN alpha and beta, which lead to the antiviral state
what is the role of NOD-like receptors
sense DAMPs and PAMPs in cytoplasm containing nucleotide oligomerization domain, and different N-terminal domains
Nod1 and Nod2
contain N-terminal caspase related domains (CARD), found in bacterial peptidoglycan in cell wall, activated NF kappa B
NLRP3
recognizes microbial products, substances associated with cell damage, and endogenous substances in too large of quantities e.g. crystals, enhances production of IL1b beta, which leads to fever
genetic defect in NLRP3
enhances production of IL1b beta, leads to periodic fever syndrome