Effector mechanisms of humoral immunity Flashcards
Effector functions of antibodies
- neutralization of microbes/toxins
- opsonization/phagocytosis of microbes
- antibody-dependent cellular cytotoxicity
- complement: phagocytosis, inflammation, lysis
Main function of antibodies
neutralize and eliminate infectious microbes and microbial toxins
antibodies are produced by what ?
- plasma cells in peripheral (secondary) lymphoid
- inflamed tissues
- bone marrow
where do antibodies perform their effector functions ?
distant from their production
effector functions of antibodies are mediated by …
Fc regions of Ig molecules & different Ig heavy chain isotypes
the effector functions of antibodies that are mediated by the Fc regions are triggered by what?
binding of antigens to the variable regions
mechanism of polio vaccine
neutralization of virus by IgG or by mucosal IgA antibody
mechanism of tetanus, diphtheria vaccine
neutralization of toxin by systemic IgG antibody
mechanism of hep A and hep B vaccine
neutralization of virus by mucosal IgA or systemic IgG antibody
mechanism of pneumococcal pneumonia, haemophilus influenzae, neisseria meningitidis vaccine
opsonization & phagocytosis mediated by IgM and IgG antibodies, directly or secondary to complement activation
Functions of IgG
- opsonization of antigens for phagocytosis via macrophages/neutrophils
- activation of classical complement
- antibody-dependent cell-mediated cytotoxicity by NK cells
- neonatal immunity (maternal antibodies cross placenta)
- feedback inhibition of B cell activation
- neutralization of microbes
Function of IgM
activation of the classical pathway of complement
Functions of IgA
- Mucosal immunity through the lumen of the gastrointestinal and respiratory tracts
- Neutralization of microbes and toxins in lumens of mucosal organs
Functions of IgE
- Mast cell degranulation (immediate hypersensitivity reactions)
- Eosinophil-mediated defense against helminths
FcRN receptor
pH-dependent that has an increased half-life and transports maternal IgG to fetus
FcγRIIA, FcγRIIB & FcγRIIC receptors has ___ affinity for immunoglobulin
Low
Inhibitory Fcy receptor (w/ low affinity)
FcγRIIB
Activating Fcy receptors
- FcyRI
- FcyRIIA/C
- FcyRIII-A
- FcryRIII-B
Which activating Fcy receptor have high affinity for immunoglobulin?
FcyRI
Which activating Fcy receptor have low affinity for immunoglobulin?
- FcyRIIA/C
- FcyRIII-A
3.FcγRIII-B
FcyRI activates
CD64
FcyRIIA/C activates …
CD32
FcyRIII-A and FcyRIII-B activates
CD 16
FcγRIIB inhibits
CD32
Select all that apply: Cell distribution of FcyRI (CD64)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes
Macrophages, neutrophils and Eosinophils (MEN)
Select all that apply: Cell distribution of FcyRIIA (CD32)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes
Platelets, Eosinophils, Neutrophils, Dendritic cells and Macrophages (PENDM)
Select all that apply: Cell distribution of FcyRIIB (CD32)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes
B cells, Macrophages, Dendritic cells (BMD)
Select all that apply: Cell distribution of FcyRIIC (CD32)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes
NK cells, Neutrophils and Macrophages (NKNM)
Select all that apply: Cell distribution of FcyRIIIA (CD16)
A. Macrophages
B. Neutrophils
C. Eosinophils
D. Dendritic cells
E. Mast cells
F. Platelets
G. B cells
H. NK cells
I: Basophils
J: Langerhans cells
I: Monocytes
NK cells, Macrophages, Dendritic cells (NKMD)
Cell distribution of FcyRIIIB (CD16)
Neutrophils