Flashcards in Immunity to Microorganisms Deck (35):
What is the primary local adaptive immune response to bacteria? primary serum response?
antibody response, IgA for local, IgG for serum
How are microorganisms actually destroyed in most cases?
What are killed by cytotoxic T cells?
infected host cells
What two things does specific immunity act to enhance?
uptake of microorganisms by phagocytic cells, activity of phagocytic cells
Where is lysozyme present? What does it do?
tears, nasal secretions, saliva, enzymatically destroys cell walls
What cells innately recognize bacteria?
neutrophils and macrophages
How are bacteria broken down in macrophages?
NADPH-oxidase, has buildup of reactive oxygen species that breakdown bacteria
What are spreading factors?
collagenase and elastases that breakdown tissues to allow bacterial spread
What does protein A do? What bacteria has it?
binds to the Fc region of IgG and blocks opsonizing action of IgG since it can't be recognized by immune cells now, s. aureus
What is M protein?
antiphagocytic factor found in strep.
How does Ab respond to virulence factors of bacteria? (5)
1. prevent attachment to epithelim using secreted IgA
2. trigger complement to increase opsonization or lysis
3. bind antiphagocytic M protein or capsule
4. neutralize toxin
5. neutralize spreading factors
What microorganisms act on the epithelial surface? What is the protective immunity?
N. gonorrhea, c. albicans, worms
IgA, antimicrobial peptides
What microorganisms are cytoplasmic? What is the protective immunity?
viruses, chlamydia, protozoa
cytotoxic T cells, NK cells
What microorganisms are vesicular? What is the protective immunity?
mycobacteria, trypanosomes, cryptococcus neoformans
Is Ab helpful in killing of facultative IC parasites?
No, they increase the rate of phagocytosis but don't affect clearance
How are macrophages activated?
How doe activated macrophages kill IC parasites?
non-specific killing from increased reactive oxygen and reactive nitrogen species in the macrophage
What cells are the memory cells in CMI?
memory CD4+ T cells
Do activated macrophages have memory?
No, they exist for a short time only and have non-specific killing
Can dead bacteria elicit CMI?
No, only live bacteria produce CMI
Describe Th1 cytokines and effects.
stimulates CMI, activates macrophages
activates B cells to produce opsonizing Ab
Describe Th2 cytokines and effects.
stimulate Ab production
What is the important role of IFNgamma?
How do CD8+ cells lyse infected host cells?
FasL of CTL binds Fas on infected cell, cytotoxins (perforin, granzymes, granulysin)
Why are T cells critical for immunity to parasites?
needed for activation of macrophages, don't directly kill
What is the role of CTLs in immunity to parasites?
kill cells infected with parasite so pathogen is released and can be eaten by activated macrophage
Why are granulomas formed in response to parasite?
wall parasite off from rest of the host because of release of fibroblast growth factor from activated macrophages
How do eosinophils kill parasites?
release of major basic protein
Which antibody is most important against helminths?
How do parasites escape immune response? (4)
inaccessibility (hide in host cells, form cysts), avoid recognition by varying surface Ag expression, immunosuppression of host, survive inside macrophage
What is the importance of Ab in viral immunity?
prevent infections by neutralizing virus
What is the prime mediator of antiviral immunity in respiratory, GI or GU tracts?
IgA neutralization response
What kind of viruses can be lysed by action of Ab and complement?
How do interferons act in antiviral immunity?
IFNgamma activates macrophages to kill virus-infected cells
IFNa and IFNb produced by macrophages induce reduced susceptibility of neighbors to viral infection