immunology 4 Flashcards
homeostasis
balance between pathogen and immune response
hypersensitivity, autoimmune disease
immune response outweighs the pathogen
infectious disease
pathogens outweighs immune response
Innate immune defense
epithelial barrier
secretion
endogenous microflora
resident phagocytes
pattern recognition receptor
epithelial barrier
skin, respiratory epithelium and enterocytes
secretion
mucus, sweat, sebum, cerumen, acid, enzymes, defensin, polyreactive antibodies surfactant (IgA)
TLR2
peptidoglycan and gram positive bacteria
TLR3
dsDNA and viruses
TLR4
lipoplysaccharide and gram negative bacteria
TLR6
peptidoglycan and lipoteichonic acid and gram positive bacteria
TLR7, 8
ssRNA and viruses
TLR9
non-methylated DNA and viruses and bacteria
adaptive immune response
cell mediated and humoral
cell mediated
mediated by TH1 cells
most important intracellular pathogen
humoral
mediated by TH2 cells
most important extracellular pathogen
viral infection
bind to cell receptor (Absoption)
virions enter cell
nucleic acid released into cytoplasm
replication
protein production
assembly
release
spread
what triggers the innate immune response to viral infection
recognition of viral patterns by Pattern recognition receptor (PRR)
RIG-1, MDA5 (cytoplasmic)
TLR3, 7, 8, 9 (endosomal)
cell damage
interferons
glycoproteins
three types
type 1-alpha dendritic cells, beta any virally infected cells
type 2-gamma activated TH1 cells
type 3-various, mucosal epithelial cells
regulate protein expression
type 1 interferons
produced upon recognition of TLR7 and TLR9 ligands
activate JAK/STAT pathways
increased production of antiviral and immunoregulatory protein
directly inhibit viral uptake, replication
induce apoptosis
produced withing hours (before antibodies)
humoral immunity in viral infections
antiviral antibodies against viral proteins
antibody binding prevents viral infection by-blocking viral invasion
stimulating phagocytosis
triggering complement-mediated virolysis
promoting viral clumping
not by direct virus destruction
ADCC target infected cells for destruction
nk cells and cytotoxic t cells
cell mediated immunity to viral infection
cytotoxic t cells recognized infected cells prior to rupture
induce apoptosis
recognized peptide MHC-1 complexes and kill cells
sensitized by type 1 interferons
macrophages are activated by Th1 cells and cause phagocytosis
immune evasion by viruse
RNA viruses rely on antigenic variation
DNA viruses use immunoregulatory genes-proteins that block IFN signaling
proteins that interfere with MHC-1 associated antigen presentation
evasion of NK cells
alteration in humoral immunity
antigenic variation
antigenic variation
point mutation and poor editing
sporadic recombination of strains
influenza A
bacterial infection
presence of bacteria does not indicate bacterial disease
development of disease depends on-bacterial virulence factors
dose of bacteria
concurrent disease or tissue damage
normal flora
immune system function
mechanism of bacterial colonization/invasion
opportunistic bacteria-break in epithelium
pathogenic bacteria-wide range of mechanism
simple-induce phagocytosis
complex-inject proteins into the host cells to create a receptor
innate immune system response to bacteria
bacteria are recognized through PRR (TLR1, 2, 4, 5, 6, 9)
cytokine release, complement activation, inflammation and phagocytosis
sequestration of nutrients (iron and tryptophan)
adaptive immunity in bacteria infection-extracellular
humoral immunity-neutralization of toxin
opsonization by antibodies
killing by classical complement pathway
phagocytosis by activated macrophages
adaptive immunity in bacterial infection-intracelluar
cell mediate immunity
macrophage activation and killing
destruction by cytotoxic T cells
neutralization
important for toxogenic bacterial
antibodies generated against toxin
blind
prevent interaction with receptor
can be IgG or IgA (mucosal surfaces)
opsonization and phagocytosis
opsonization increased efficiency of phagocytosis
antibodies against surface antigens
bacteria coated in antibodies and complement fragments are primed for phagocytosis
IgM is the most efficient antibody in opsonization
destruction by activated macrophages
some bacteria can replicate inside macrophages
Th1 cells activate macrophages by secreting interferon gamma
acidification of phagosomes
intracellular bacterial destruction
NK and cytotoxic T cells can also kill cells infected with intracelluar bacteria
bacteria evasion of innate defenses
interfere with TLR signaling-modify PAMPS and interfere with intracellular signaling
resistance to antibacterial peptides
block phagocytosis
intracellular bacteria
evasion of adaptive defense
antigenic variation
secrete proteases to destroy antibodies or cytokines
