Immunity to Microorganisms Flashcards
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?
phagocytic cell
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)
- prevent attachment to epithelim using secreted IgA
- trigger complement to increase opsonization or lysis
- bind antiphagocytic M protein or capsule
- neutralize toxin
- 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
macrophages
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?
Th1 response
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.
IL-2, IFNgamma
stimulates CMI, activates macrophages
activates B cells to produce opsonizing Ab
Describe Th2 cytokines and effects.
IL-4, IL-5
stimulate Ab production
What is the important role of IFNgamma?
activates macrophages
How do CD8+ cells lyse infected host cells?
FasL of CTL binds Fas on infected cell, cytotoxins (perforin, granzymes, granulysin)
