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78 Cards in this Set

  • Front
  • Back
Microbes elicit a variety of immune responses, many of which are __1__, but not __2__
1. diagnostic

2. protective

*seroconversion during viral infections
Immunity that is important during early infection in immunized hosts
Innate immunity
When is Adaptive Immunity most apparent?
after Secondary Challenge of immune hosts
Adaptive Immunity:
-__1__-specific recognition
-important in __2__ of many infections
-is the basis for all current __3__
1. epitope
2. resolution
3. vaccines
Define "Clearance"
elimination of a microbe from the circulation or a particular tissue site
Define "Killing"
any mechanism using immune components to effect damage and death of the microbe
Define "Resolution"
final elimination of all the organisms from the host
In what 2 instances may Resolution not occur?
Chronic Latent infections

CGD patient who can't make a respiratory burst and just wall off the infection
Specific receptor involved in innate immunity
Toll-like receptor
Ig's involved in Toxin Neutralization
IgM, IgG, IgA

Toxins that are more effectively neutralized
Exotoxin > Endotoxins
Toxins serve as excellent __1__ targets
-most toxins are __2__
1. vaccine
2. proteins
2 components of Virus Neutralization
1. Serum (viremia) = cleared from blood

2. Mucosal Immunity = prevents their attachment to mucosal surface
Phagocyte-mediated Extracellular Killing:
1. Effector cell
2. Killed organisms (2)
1. Neutrophil

2. EC fungi and parasites
2 groups of organisms killed by Opsonophagocytosis and Intracellular killing
1. "pyogenic" bacteria
-Staph, Strep, Pseudomonas

2. EC fungi
-Candida, Aspergillus
List 3 phagocytic receptors
1. FcR (binds to Fc of IgG)
2. C3b receptor
3. Mannose receptor
List 4 opsonins
1. IgG
2. C3b
3. Mannose
4. LPS (on Gram-)
By what mechanisms is intracellular killing performed by neutrophils?
Respiratory burst

NO-dependent killing
Macrophage-mediated intracellular killing:
- 2 types of organisms
- what is important for macrophage activation?
1. Intracellular bacteria
*Rickettsia + Chlamydia = obligate
*BFLS-ella + LYM

2. Fungi
-Candida, Cryptococcus, Histoplasmosis

Th1 cytokines = IFN-gamma
Pathogens killed by CTL-dependent killing
1. viruses

2. Intracellular bacteria that escape the Phago(lyso)some
-Listeria monocytogenes, Francisella
Eosinophil-mediated killing:
- immune components involved

- pathogens affected
1. IgE antibody and ADCC

2. Parasites (intestinal Helminths)

*via lytic enzymes + Perforin
Targets for NK-cell killing
Latent viruses that inhibit MHC-I expression

Tumor cells
NK cells are a major source of what?
IFN-alph, beta, gamma
2 major roles of Complement
1. Opsonin = iC3b (most bacteria; many fungi)

2. Chemoattractant = C5a (attracts Neutrophils)
2 pathogens in which Complement lysis is essential
Neisseria (deficiency of C5-C9)

Cytokine that causes Apoptosis of infected cells
Defensins, cathelicidins, and other natural microbiocidals are especially important against these pathogens
Anaerobic bacteria
What are the 3 ways in which we can determine the ESSENTIAL protective immune mechanisms?
1. infections in the IC'ed
2. MICROBIAL EVASION mechanisms underscore the most effective defense mechanisms of the host
3. Empiric evidence from successful VACCINES
List 3 toxigenic bacteria
List the intracellular bacteria
Obligate = Rickettsia and Chlamydia

Faculative = BFSL-ella + LYM
List 3 latent/chronic viruses

What is one acute virus

What are enveloped viruses susceptible to?
Complement-mediated lysis
Fungi that pose a significant immunological challenge
How are Protozoan parasites fought off?
-Plasmodium, Toxoplasma
with Antibody
How are GI or tissue helminths dealt with?
-Schistosoma, Ascaris
IgE antibody and eosinophils or activated macrophages
Examples of Protective Immunity against parasites:
-IgG antibody to __1__
-__2__ killing of Toxoplasma tachyzoites.
-IFN-gamma-dependent activation of macrophages for killing of __3__ (2)
-granuloma formation in response to __4__ eggs
-__5__ elimination of Schistosomes.
1. Malaria merezoites
2. Th1-activated macrophage
3. Leishmania and Trichinella
4. Schistosome
5. Eosinophil + IgE-mediated
5 major effectors used against extracellular bacteria
1. Antibody
2. Complement
3. Neutrophil
4. Th2 cell
5. NK cells cytokines
Defense effectors of IC bacteria
++ Th1 cell
++ Macrophage
+ NK cell
+/- Neutrophil
Antibodies are most effective against what types of infections? (2)
1. Extracellular bacteria

2. Cytolytic viruses

*prevents entry and mediates clearance to a killing compartment
What is Complement most effective at protecting against?
1. LYSING Meningococcus and Enveloped Viruses

2. CLEARING all EC pathogens via opsonic iC3b
What is the Th1 response most effective against?
Intracellular pathogens (bacterial, viral, fungal) via activation of Macrophages and CTL
What is CTL-mediated immunity most effective against?
Intracellular pathogens (viral and some bacterial)
What are Neutrophils most effective against?
Extracellular bacteria and fungi

(chemotaxis, phagocytosis, respiratory bursts)
What are NK cells most effective against?
Viruses (IFN; lysis)
Bacteria (IFN-gamma)

*recognize cells lacking MHC-I
Macrophages mediate responses to __1__ pathogens and clear __2__ pathogens
1. intracellular (respiratory burst, NO)

2. Extracellular
What are Respiratory bursts effective against?
Phagocytized microbes
Nitric Oxide is effective against?
a limited # of microbes
-M. tb.
What is IFN-alpha,beta most effective against?
What is IFN-gamma most effective against?
Intracellular bacteria, fungi, or parasites

(activates macrophages)
Patients with Antibody deficiencies present with what infections and when?
Extracellular bacterial infections at >6 months of age
How do patients with Complement deficiencies present?
Extracellular, Pyogenic bacterial infections
How do patients with T cell deficiencies present?
Intracellular pathogens (viral, fungal, parasitic) at <6 months of age
How do Phagocytic cell deficiencies present?
with selected organisms of low virulence (extracellular bacterial and fungal)
If a person has low levels of IgG2, what are they susceptible to?
Capsular organisms = Streptococcus Pneumonia = Gram + diplococci

*Some Killers Have Pretty Nice Capsules
-Strep pneumo
-H. influenza
-P. aeruginosa
-Neisseria meningitidis
-Cryptococcus neoformans
What infection may occur if a patient has an IFN-gamma receptor deficiency?
M. avium intracellulare
What conditions could predispose to infection by Aspergillus? (4)
1. Methotrexate/cyclophosphamide = neutropenia
3. CGD; neutropenia
4. Glucocorticoid therapy
Phagocytic deficiency can lead to infections by these 5 organisms
H. influenza
Complement deficiencies can lead to infection by these 3 pathogens
T cell or CMI deficiency can lead to infection by these 8 pathogens
Herpes family (CMV,HSV,EBV)
JC virus
B cell and Antibody deficiency can lead to infection by these 6 pathogens
H. influenza
2 viruses that inhibit the expression of MHC

2 viruses that mimic cytokines or their receptors

3 protective immune mechanisms that vaccines may provide
1. Neutralizing antibodies
-microbial toxins
-viruses causing acute disease

2. Opsonizing antibodies to EC bacteria

3. Cellular Immunity to Intracellular bacteria and viruses
Example of a vaccine that induces CELLULAR IMMUNITY (CMI)
Measles and Mumps
How are most vaccines developed?
Emperically = derived by experiment
Vaccines reduce __1__, but they rarely prevent __2__.
Many of the best vaccines induce __3__ antibodies.
1. disease
2. infection
3. neutralizing
Most vaccines are __1__; there are very few __2__ vaccines
1. preemptive
2. therapeutic
What are 2 therapeutic vaccines?

Current vaccines are all directed against __1__, not __2__.
We have few effective vaccines against __3__ microorganisms
1. epitopes
2. microbial patterns
3. complex (i.e. parasites)
What is an example of when a lethal dose is less than the immunizing dose?
Tetanus toxoid
Example of when an infection outpaces the immune response
Example of when multiple antibody isotypes are advantageous
HiB conjugate
Example of when pre-exposure antibodies might prevent disease or spread of infection
2 vaccines that cause toxin neutralization
2 vaccines that inhibit bacterial attachment
2 vaccines that elicit antibodies to Polysaccharides
Virus vaccine that elicits Antibody neutralization of the virus
Virus vaccine that is presented as MHC-epitopes
When are parasite vaccines important?
where reinfection is common