EXAM 2 Immediate Immunity: Barriers and Soluble Effectors I Flashcards
what is innate immunity?
- a generalized host defense mechanism that continuously acts from the start of an infection and does not adapt to a specific pathogen or generate immunologic memory
- includes immediate and induced innate immunity
what 2 main components make up the immediate immune system?
barriers and soluble effectors
what are the barriers in immediate immunity?
mechanical, chemical, and microbiological
what are the soluble effectors of immediate immunity?
complement and antimicrobial peptides
what 2 components make up induced immunity?
cells and cytokines
what are the cells of induced immunity?
- neutrophils
- monocytes
- macrophages
- dendritic cells
- NK cells
- mast cells
- eosinophils
- basophils
what are the cytokines of induced immunity?
- interleukins
- chemokines
- growth factors
innate immunity is a system of ___
pattern recognition
types and compositions of extracellular and cell surface proteins, carbohydrates, and lipids activate ___
specific immune responses
what are the classes of molecular patterns of innate immunity effector pathways?
- pathogen-associated molecular patterns (PAMPs)
- damage-associated molecular patterns (DAMPs)
what are the 4 PAMPs of innate immunity effector pathways?
- lipopolysaccharide (LPS)
- flagellin
- mannose sugars
- unmethylated CpG DNA
when do the immediate and induced innate responses begin?
- immediate: 0-4 hours
- induced: 4-96 hours
what are the 3 DAMPs?
- heat shock proteins
- fibronectin
- chromatin
what are pattern recognition receptors (PRRs)?
bind to specific things that are commonly expressed on pathogen surfaces
what are the mechanical, chemical, and microbiological barriers that the skin provides?
- epithelial cells joined by tight junctions
- longitudinal flow of air or fluid
- fatty acids
- beta-defensins, lamellar bodies, cathelicidin
- normal microbiota
what are the mechanical, chemical, and microbiological barriers that the gut provides?
- epithelial cells joined by tight junctions
- longitudinal flow of air or fluid
- low pH
- enzymes
- alpha-defensins, RegIII, cathelicidin
- normal microbiota
what are the mechanical, chemical, and microbiological barriers that the lungs provides?
- epithelial cells joined by tight junctions
- movement of mucus by cilia
- pulmonary surfactant
- alpha-defensins, cathelicidin
- normal microbiota
what are the mechanical, chemical, and microbiological barriers that the eyes/nose/oral cavity provides?
- epithelial cells joined by tight junctions
- tears, nasal cilia
- enzymes in tears and saliva
- histatins, beta defensins
- normal microbiota
mechanical barriers prevent ___
infiltration
mechanical barriers physically block ___
pathogens
mechanical barriers are not ___
passive
what are 3 examples of mechanical barriers?
epidermis of skin, bronchial ciliated epithelium, cut epithelium
specialized ___ tissues are integrated into barriers
immune (lymphoid tissues)
lymphoid tissues provide ___ terminology
tissue-specific
lymphoid tissues provide localized activation of what 2 cells?
T and B cells
lymphoid tissues have less structure than ___
lymph nodes
what are two functions of chemical barriers that act on pathogens?
- isolation and physical removal
- targeted destruction
describe isolation and physical removal of pathogens by chemical barriers
every mucosal tissue:
- secretion - traps pathogens
- motility (ex. cilia) - removes pathogens from mucosal surfaces
describe targeted destruction of pathogens by chemical barriers
- lysozyme cleaves peptidoglycans on gram positive and gram negative bacterial cell walls
- exposes lipid bilayer and plasma membrane
- allows other things (complement and defensins, for example) to bind those surfaces and destroy the cell
what are the most common types of chemical barriers?
peptides and proteins are the most common, but some lipids and carbohydrates serve as chemical barriers
describe the location and antimicrobial activities of lysozyme (chemical barrier)
- location - mucosal/glandular secretions (tears, saliva, respiratory tract)
- antimicrobial activities - cleaves glycosidic bonds of peptidoglycans in cell walls of bacteria, leading to lysis
describe the location and antimicrobial activities of lactoferrin (chemical barrier)
- location - mucosal/glandular secretions (milk, intestine mucus, nasal/respiratory and urogenital tract)
- antimicrobial activities - binds and sequesters iron, limiting growth of bacteria and fungi; disrupts microbial membranes; limits infectivity of some viruses
describe the location and antimicrobial activities of defensins (alpha and beta; chemical barriers)
- location - skin, mucosal epithelia (mouth, intestine, nasal/respiratory tract, urogenital tract)
- antimicrobial activities - disrupt membranes of bacteria, fungi, protozoan parasites, and viruses; additional toxic effects intracellularly; kill cells and disable viruses
describe how defensins disrupt pathogen membranes
- electrostatic attraction and the transmembrane electric field bring the defensin into the lipid bilayer
- defensin peptides form a pore
in what ways do alpha and beta defensins act as signaling molecules?
chemotaxis, ACTH antagonist, opsonization, interaction with complement, cytotoxicity and growth promotion, wound repair and cell migration, and histamine release
defensins are prominent in the ___
oral epithelium
describe the defensins that are prominent in the oral epithelium
- neutrophils are induced to secrete alpha-defensins into the GCF
- stratified oral epithelium constitutively release beta-defensins
___ and ___ bacteria form barriers
mutualistic and commensal
both aerobic and anaerobic genres
describe mutualistic, commensal, and parasitic relationships
- mutualistic - both organisms benefit (most common)
- commensal - one organism benefits, the other is unaffected
- parasitic - one organism benefits, the other suffers
what are the protective functions of mutualistic and commensal bacteria?
- pathogen displacement
- nutrient competition
- receptor competition
- production of antimicrobial factors
what are the structural functions of mutualistic and commensal bacteria?
- barrier fortification
- induction of IgA
- apical tightening of tight junctions
- immune system development
what are the metabolic functions of mutualistic and commensal bacteria?
- control IEC differentiation and proliferation
- metabolize dietary carcinogens
- synthesize vitamins
- ferment non-digestible dietary residue and endogenous epithelial-derived mucus
- ion absorption
- salvage of energy
mucosal flora interact with the immune system
___ peptides shape local gut flora
antimicrobial (ex. beta defensins)
mucosal flora interact with the immune system
commensal flora outcompete ___
pathogenic bacteria
mucosal flora interact with the immune system
___ detect commensal bacteria and prevent inflammation
pattern recognition receptors (PRRs)
mucosal flora interact with the immune system
commensal bacteria induce ___ and ___ secretion
IgA and antimicrobial peptide
mucosal flora interact with the immune system
___ cells constantly browse mucosal flora
dendritic
what is the complement system?
an immune surveillance system of plasma proteins that act in cascades to selectively kill extracellular pathogens and diseased tissue, promote inflammation, clear tissue damage, and regulate tissue homeostasis
what are the 3 pathways of the complement system?
- classical pathway
- lectin pathway
- alternate pathway
describe the classical pathway
- it was the first pathway identified, and is the first one to activate
- interaction between immunoglobulins produced by B cells and the complement system
complement is a ___ system
pattern recognition
most components of the complement system are made in the ___
liver
the complement system is evolutionarily ___
ancient
what are the 7 complement components?
- initiators
- convertase activators
- opsonins
- anaphylatoxins
- membrane attack complex
- complement receptors
- regulators
what is the predominant site of synthesis of alpha defensins?
neutrophils are the most common site, but alpha defensins are also synthesized from paneth cells
what is the most common site of synthesis of beta defensins?
epithelial cells
