Innate Immunity Flashcards
innate immune system consists of
- all the immune defense that lack immunologic memory
characteristic of innate responses
- they remain unchanged however often the antigen is encountered
presence of innate immunity
- always working and present in healthy people
how do phagocytic cells identify pathogens
- recognition of PAMPS and DAMPs
PAMPS stands for
- pathogen associated molecular patterns
DAMPS stands for
- damaged/necrotic self
- damage-associated molecular patterns
coagulase negative staph on the skin
- produce an antimicrobial peptide that can inhibit growth of Staphyloccous aureus
how does innate immunity distinguish between foreign and self?
- responds to motifs that are characteristic of microbes but not of mammalian cells
- gram negative LPS
- viral double stranded RNA
dendritic cell type
- bone marrow derived cell
dendritic cell function
- phagocytosis
- initiation of T-cell responses
another name for neutrophil
- polymorphonuclear leukocyte
- PMN
where do PMNs develop
- the bone marrow
function of PMN
- phagocytic cells
PMN characteristics
- phagolysosome
- respiratory burst
PMN phagolysosome
- engulf substances in vesicles called a phagolysosome where the microbe is killed and degraded
PMN respiratory burst
- potent respiratory burst of reactive oxygen species to kill engulfed bacteria
life time of PMN
- less than 2 days
macrophages are derived from
- monocytes
- when they migrate into tissue spaces, they differentiate
macrophages characteristics
- phagocytic
- create phagolyososome
macrophage function
- serve to kill and degrade antigens
- also present peptides from those antigens
- professional antigen presenting cell (APC)
dendritic cells important in
- immunosurveillance
dendritic cells function
- present antigen to T cels
how to dendritic cels pick up antigen
- through endocytosis
- less phagocytic than neutrophils and macrophages
follicular dendritic cells location
- specialized stroll cells in lymph nodes and spleen
follicular dendritic cells function
- trapping antigen
- presenting antigen to B cells
natural killer cells origin
- arise and mature in bone marrow
natural killer cells contain
- granzyme
- perforin
- cell surface receptors for IgG
function of natural killer cells
- destroy virally infected and malignant cells
innate immune responses mediated by
- proteins that recognize and interact with components specific to microbes
- pattern recognition receptors
PAMPS
- microbial molecules that stimulate innate immunity
two groups of pattern recognition receptors
three groups
- secreted and circulating proteins and peptides
- transmembrane and intracellular signal-transducing receptors
- extracellular
- cytosolic
- endosomal
what does the innate immune system recognize
- structures that are shared by various classes of microbes
- not present on normal host cells
what components of immunity recognize
- bacterial endotoxin or LPS
- terminal mannose residues of bacterial glycoproteins
- dsRNA in viruses
- unmethylated CG rich oligonucleotides in microbial DNA
TLRs located on cell surfaces are specific for
- microbial proteins
- lipids
- polysacchardies
TLRs that recognize nucleic acids are located where
- endosomes
- where microbes are engulfed
what does TLR-2 recognize
- several bacterial and parasitic glycolipids and peptidoglycans
what do TLR-3,-7, and -8 recognize
- viral ss and ds RNA
- TLR-7 and -8 ss RNA
- TLR-3 ds RNA
what is TLR-4 specific for
- bacterial LPS
- endotoxin
what is TLR-5 specific for
- bacterial flagellar protein
- flagellin
what does TLR-9 recognize
- unmethylated CpG DNA
- abundant in microbial genomes
why have microbes not adapted to avoid motifs recognized by innate immunity
- innate immunity targets motifs that are indispensable to the microbes
primary reactions of the immune system
- acute inflammation
- antiviral defense
acute inflammation
- recruitment and activation of leukocytes and plasma proteins at sites of infection or tissue injury
innate immune defense against intracellular viruses mediated mainly by
- interferon system
components of interferon system
- type I
- type II
type I interferons
- alpha
- beta
type II interferons
- gamma
what detects a virus attack
- pattern recognition receptors on plasmacytoid dendritic cells (pDC) and macrophages
what warning proteins are released
- interferon alpha and beta
what TLRs do innate immunity cells use to detect viral RNA and DNA
- TLR 7 and TLR 9
function of natural killer cells
- deliver suicide enzymes to target self destruction
macrophage with phagocytosed microbes
- secretes IL-12 to recruit NK
- pokes holes in cells through perforin
- secretes IFN gamma which helps macrophage kill
- IFN gamma just makes macrophages much better at killing things
what accompanies inflammation and tissue injury
- increase in concentration of plasma proteins
- referred to as acute phase reactants
what contributes to host defense and other adaptive capabilities
- usually level of various proteins maintained by homeostatic mechanisms change substantially
IL-6
- chief stimulator of production of most acute phase proteins
other implicated cytokines
- influence subgroups of acute phase proteins
conditions that commonly lead to substantial changes in plasma concentrations of acute phase proteins
- infection
- trauma
- surgery
- burns
- tissue infarction
- various immunologically mediated inflammatory conditions
- advanced cancer
acute phase protein definition
- one whose plasma concentration increases or decreasing by at least 25 percent during inflammatory disorders
positive acute phase proteins
- concentration increases
negative acute phase proteins
- concentration decreases
what produces acute phase proteins
- hepatocytes
function of c reactive protein
- promotes recognition and elimination of pathogens
- enhances clearance of necrotic and apoptotic cells
pro inflammatory effects of CRP
- activation of complement system
- induction in monocytes of inflammatory cytokines
serum amyloid A proteins function
- influence cholesterol metabolism during inflammatory states
pro-inflammatory roles on complement components
- chemotaxis
- plasma protein exudation at sites of inflammation
- opsonization of infectious agent and damaged cells
haptoglobin and hemopexin
- antioxidants
haptoglobin function
- removes iron-containing cell-free hemoglobin from circulation
hemopexin function
- removes iron-containing cell free heme from the circulation
hepcidin function
- decrease serum iron
- reduces intestinal iron absorption
- impairs release of iron from macrophages
fibrinogen function
- influences wound healing
- causes endothelial cell adhesion, spreading, and proliferation
clinical use of serum acute phase reactant proteins
- abnormalities reflect presence and intensity of an inflammatory process
limits of APR measurement
- cannot distinguish infection from other causes of acute and chronic inflammation
a person lacking innate immune response
- shows uncontrolled infection
a person lacking adaptive immune response
- shows initial containment but not effectively cleared from the body
