Effector Responses: Antibody-Mediated Immunity Flashcards
Describe humoral immunity.
- antibodies produced by B cells
- antibodies transferred and provides passive immunity
List the 6 antibody-mediated effector functions.
- Neutralization: protects against viral or bacterial infection
- Agglutination: enhances neutralization
- Opsonization: helps macrophages by promoting the engulfment of antigens
- Complement activation: MAC complex creates pores in pathogen to kill microbe
- Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC): activates cytotoxic cells , NK cells
- Antibody-Dependent Degranulation and Mediator Release: triggers release of granules
How do antibodies contribute to clearing infection?
- determines which receptors can bind
- determines which cells become activated
- determines which locations it can gain access in the body
Which antibody is the most abundant in the body and what are its functions?
- IgG
- effective at complement fixation
- mediates ADCC by NK cells
- bind Fc receptors and enhance phagocytosis
Identify this antibody and its function.
- IgM
- first antibody produced
- lower affinity
- pentamer
- complement fixation: activates MAC complex for cell lysis
- macrophages love IgM
Identify this antibody and function.
- IgA
- found in secretions (mucus, milk, tears, saliva)
- neutralizes toxins
- does NOT drive inflammation
- protease-resistant, long half life
Name this antibody based on its functions.
- known for allergy and asthma
- protection against parasites and protozoa
- degranulation
- releases histamine
IgE
What is the function of IgD?
- present in upper respiratory tract secretions
- binds to basophils and mast cells to stimulate granule release
Which part of the BCR mediates effector functions?
Fc region
If a signal in Fc receptors is positive or negative it depends on …
ITAM or ITIM
List the different Fc receptors.
- FcγR
- FcεR
- PolyIgR
- FcRn
What is the main function of FcγR?
- activating receptors
- induce phagocytosis
- induce granulation
- ADCC
What is the main function of FcεR?
- expressed by granulocytes
- releases histamines
- releases granules
- associated with allergies
What is the function of PolyIgR?
- J chain binds to this receptor
- expressed by epithelial cells
- transports IgA and IgM from blood to mucosal tissues
- carries antigens into tear and milk
What is the function of FcRn?
- neonatal Fc receptor
- related to MHC class I
-carry antigen ingested in milk across epithelial cells into bloodstream
List the antibody and FcR effector functions.
- opsonizing pathogens for phagocytosis
- activating complement cascade for lysis
- inflammation
- recruits cytotoxic cells
- activating NK cells, ADCC
