Immuno

Question 1

TQ

-Acquired through placental IgG transport, breast feeding IGA

Answer 1

Passive + natural vaccination

active=acquired through recovery from infx

Question 2

-Acquired through IV injection of anti-serum

Answer 2

Passive + artificial vaccination

active=immunization w/ vaccines

Question 3

-Do not PREVENT infx, rather reduce severity of dz
»Th2 response
-Only rabies and hepatitis are therapeutic
-Primes immune response vs pathogen so that when you encounter it, you can fight it quickly w/ Abs & memory cells

Answer 3

Vaccines

directed at Ag epitopes»adaptive immunity

Question 4

What kind of vaccine is…

Oral polio, varicella; mumps, measles, rubella, bacillus Calmette-Guerin (BCG)?

Answer 4

Live attenuated

Question 5

What kind of vaccine is…

Inactivated polio

Answer 5

Killed/inactivated

can be used anytime

Question 6

What kind of vaccine is…

Diphtheria toxoid, tetanus toxoid

Answer 6

Subunit

only some Ags

Question 7

What kind of vaccine is…

Hep B

Answer 7

Recombinant subunit

Ags are recombinant

Question 8

What kind of vaccine is…

Haemophilus influenzae type b, Streptococcus pneumoniae

Answer 8

Conjugate (polysaccharides-protein)

Streptococcus pneumoniae can also be given in polyvalent form (large # of Ags)

Question 9

Passive immunization:
Ab from other species may cause systemic anaphylaxis (IgG)…otherwise known as what?
OR
May induce type III hypersensitivity with activation of complement in the tissues

Answer 9

serum sickness

Question 10

Active immunization:
IM inactivated & live attenuated influenza vaccine & yellow fever vaccine are grown in chicken eggs…What does this pose a risk for?

Answer 10

allergic rxn if egg allergy

Question 11

• Infant immunity is not competent»infx

- Incr morbidity in neonates due to what?

Answer 11

• Bacteria: group B streptococci & E. coli
• Viruses: HSV, CMV, VZV, RSV (decr Th1)
• Fungi: Candida

Question 12

Is cell-mediated immunity transferred from mother to fetus?

Answer 12

NO, humoral is!

Infants rely on their own T cells to fight pathogens and respond to vaccination

Question 13

TQ

Neonates have delayed IL-2 producing DC and therefore have impaired…

Answer 13

Th1 responses

Question 14

How does cell mediated immunity work?
Th1 initiated when DC or Mφ eat pathogen»
IL-12 stim NK cells incr Th1 effector cells»???

Answer 14

IFN-γ»
Activates Mφ» pro-inflam cytokines IL-1β, TNF-α, IL-12.

(IFN-γ also promotes pathogen killing by macrophages)

Question 15

TQ
Vaccination in newborn…low T cell response*

What are some examples?

High response to BCG though!

Answer 15

• (HBVac) or oral poliovirus (OPV) vaccines»Th1 type responses that are lower than those seen in adults
• Diminished delayed-type hypersensitivity (DTH) skin test reactions to Ags such as candida and tetanus toxoid

Question 16

Abs against bacteria are directed against what?

Answer 16

cell wall Ags

Question 17

What is the principal mechanism of defense against TI polysaccharide-rich Ags of encapsulated bacteria?

Answer 17

Humoral immunity

Question 18

What is the major protective immune response against extracellular bacteria?

Answer 18

Humoral immunity

Blocks infx, eliminate microbes, neutralize toxins, phagocytosis, complement activation

Question 19

TQ

Why were conjugate vaccines made?

Answer 19

To overcome the poor response to polysaccharide Ags by complexing polysaccharide Ags to immunogenic proteins, thus converting them into “T cell-dependent” Ag.

Question 20

IgA, IgM, IgD, and IgE do NOT cross the placenta. If elevated IgM or IgA are seen in cord blood, what does this suggest?

Answer 20

Intrauterine infx

Question 21

Which Ig rises rapidly 1 mo after birth as a response to the massive antigenic stimulation present in new environment

Answer 21

IgM

Question 22

TQ

Why is their a higher frequency of gram-negative infxs in newborns?

Answer 22

IgM isn’t effective as Ab produced later…doesn’t provide sufficient heat-stable opsonins

Question 23

TQ

Which infants have low opsonic activity for all types of organisms?

Answer 23

Premature infants (receive less maternal IgG)

Question 24

-Many bacterial polysaccharides of encapsulated bacteria are TI Ags.

What is the major mechanism of host defense against infx against encap bacteria?

Answer 24

Humoral immunity

Question 25

Transient hygogammaglobulinemia of infancy...most of the Igs are from mom's IgG, but are higher/lower than moms (baby + mom). Premature infants have lower IgG.

Answer 25

higher

Question 26

TQ | Full-term neonates produce Ab to TD protein Ags such as tetnus and....

Answer 26

- diphtheria toxoids - hepatitis B surface Ag - OPV

Question 27

TQ Responses to TI Ags (polysaccharide) are severely blunted until approximately 18 to 24 months of age. What are some examples?

Answer 27

Capsular polysaccharides of: - H. influenzae type b - Group B streptococci

Question 28

TQ | Why were conjugate vaccines made?

Answer 28

Overcome the poor response to polysaccharide Ags by complexing polysaccharide Ags to immunogenic proteins, thus converting them into “T cell-dependent” Ag.

Question 29

- Memory cells are generated in germinal centers for T-dep protein Ags - Memory cells are 1 of 4 types of B-cells. What are the 3 others?

Answer 29

- Antibody secreting cells - Isotype switching cells - Affinity maturation cells

Question 30

- TD Ags (proteins) and TI Ags (nonproteins) induce Ab responses with different characteristics. - The differences largely reflect the influence of Th cells in the responses to protein Ags. What are some differences?

Answer 30

TD-Ag-->isotype switching, affinity maturation, and memory B cells TI-Ag-->low switching, no affinity maturation, no memory B cells

Question 31

-Many non-protein Ags (polysacc and lipids) stimulate Ab w/o Th cells What are these Ags cells called? Abs to these Ags are of low affinity and consist mainly of IgM, with limited isotype switching.

Answer 31

Thymus independent (TI)

Question 32

Most TI Ags are multivalent=composed of many identical Ag epitopes. Why is this impt?

Answer 32

Maximal cross-linking of the BCR complex on specific B cells>> Activation without T cell help!!

Question 33

TQ | Why is an asplenic pt at incr risk for encapsulated bacterial infx ?

Answer 33

Spleen has marginal zone B-1 cells (non-circ mature B cells) that are impt in Ab responses to TI antigens, mainly polysaccharides...produce IgM

Question 34

How are TI Ags (polysaccharides, glycolipids, and nucleic acids) processed?

Answer 34

Activate complement system by the alternative pathway>>generating C3d>>binds Ag>>recognized by CR2 on B cell.

Question 35

-Some TI non-protein Ags can induce Ig isotypes other than IgM Ex: pneumococcal capsular polysaccharide induces which Ab?

Answer 35

IgG2

Question 36

- TI Ags contribute to their generaton - In circulation of normal individuals and produced w/o exposure to pathogens - low-affinity anti-carb Abs, produced by peritoneal B-cells (GI bacteria) and MZ B-cells (spleen)

Answer 36

Natural Ab

Question 37

TQ -Effective vaccines must induce both affinity maturation & memory B cell formation (only happens if vaccine activates Th cells) -How then do you design vaccines for capsular polysacc which cannot stim T cells? What are these vaccines called ?

Answer 37

Conjugate vaccines - polysacch linked to foreign protein=hapten-carrier conjugate - Induces high-affinity Abs and memory cells notes: T cell=specific for carrier protein B cell=polysacch specific

Question 38

How does the newborn's immune sys cope w/ the surge of proinflam signals towards commensal bacteria at birth?

Answer 38

D71+ erythroid cells in neonatal human cord blood>>immunosuppression via arginase-2 allows infants to adapt!

Question 39

TQ | What is arginase-2

Answer 39

Enzyme that impairs innate immune responses, including prod of Th1-promoting TNF-a

Question 40

TQ | What challenges the idea that the suscept of neonates to infx is due to immune-cell-intrinsic defects?

Answer 40

- Decr in CD71+ cells w/ postnatal develop>>loss of immunosupp - CD71+ cells quench excessive inflam induced by abrupt colonization w/ commensal microorgan after birth

Question 41

Necrotizing enterocolitis in premature babies may occur due to what?

Answer 41

-Over-rxn to influx of bacteria since immunosuppressive CD71+ cells haven't developed Limits Th1 cytokines produced by microbes

Question 42

TQ From an eco pt of view, humans are a superorganisms, a communal collective of human + microbial cells working as one -we should tail tx to both human and microbes ex?

Answer 42

Fecal microbiota transplant