Chapter 2- Innate Immunity Flashcards
describe the specificity of the innate immune system vs adaptive
-innate: specific
- adaptive: broad range
describe the receptors for innate immunity vs adaptive
-innate: encoded in germline
- adaptive: encoded by genes produced by somatic recombination of gene segments
describe the distribution of receptors in innate immunity vs adaptive
-innate: nonclonal
- adaptive: clonal
what are the 2 principle types of reaction of the innate immune system
- stimulate acute inflammation
- anti-viral defenses
what happens in acute inflammation
accumulation of leukocytes, phagocytic cells, plasma proteins, and fluid derived from the blood at the extravascular tissue site of infection or injury
what are anti-viral defenses mediated by
- NK cell mediated killing of virus infected cells
- interferon alpha/beta
where are pattern recognition receptors found
-extracellular
- cytosolic
- endosomal
what are the types of pattern recognition receptors
- toll-like receptors (TLRs)
- NOD like receptors (NLRs)
- RIG like receptors (RLRs)
what do Toll like receptors do
-acute inflammation
- stimulation of adaptive immunity
- antiviral state
what do NOD like receptors (NLRs) do
recognize PAMPs and DAMPs in the cytoplasm and recruit other proteins to form signaling complexes such as inflammasomes that promote inflammation
what do RIG like receptors (RLRs) do
cytosolic sensors of viral RNA that respond to viral nucleic acids by inducing production of the antiviral type 1 interferons
what do epithelial barriers do
- physical barrier to infection
- killing of microbes by locally produced antibiotics
- killing of microbes and infected cells by intraepithelial lymphocytes
what do neutrophils do
- circulating phagocytic cells
- first cell type to respond to most infections
- live only a few hours in tissues
what is the most abundant leukocyte in blood
neutrophils
what do monocytes do
differentiate into tissue macrophages after entering tissues
what do macrophages do
secrete cytokines that induce inflammation and ingest and destroy microbes
- live for long periods of time in tissues
what do dendritic cells do and what is another name for them
-sentinel cells
- secrete cytokines
- present antigenic peptides to T cells
where are mast cells found and what do they do
- cytoplasmic granules
- present in skin and mucosal epithelium
- contain vasoactive amines
-cause vasodilation and capillary permeability
what do innate lymphoid cells do
produce cytokines but lack T cell antigen receptors (TCRs)
what does the complement system do
induce inflammation, opsonize microbes enhancing their phagocytosis and cause osmotic lysis of microbes
what molecules go to site of inflammation in the inflammatory response
- neutrophils
-macrophages
-T lymphocytes - complement proteins
- antibodies
what is the sequence of events in migration of blood leukocytes to sites of infection
- rolling
- integrin activation by chemokines
- stable adhesion
- migration through endothelium
what do NK cells do
- kill virus infected cells
- secrete interferon gamma which activates macrophages
what happens to the NK cell if the inhibitory receptor is engaged
NK cell not activated, no cell killing
what happens to the NK cell if the inhibitory receptor is not engaged
NK cell activated, killing of infected cell
what are IFN alpha/beta (Type I interferons) secreted by and what do they do
secreted by virus infected cells
- induce anti viral state in surrounding cells
what is the role of innate immunity in stimulating adaptive immune response
lymphocyte proliferation and differentiation
what are extracellular bacteria and fungi combated by
acute inflammatory response where neutrophils and monocytes are recruited to the site of infection and by the complement system
what are intracellular bacteria combated by
microbial killing functions of phagocytes are activated by toll like receptors and other sensors and cytokines
what are viruses combated by
type 1 interferons and NK cells
