Lecture 13: Effector Mechanisms of Humoral Immunity Flashcards
functions of antibodies against microbes and their toxins
- Neutralize these agents
- Opsonize them for phagocytosis
- Sensitize them for Ab-dependent cellular cytotoxicity
- activate the complement system
- (note that the various functions are mediated by different Ab isotypes)
The influenza viruses use their envelope _______ to infect respiratory epithelial cells
Hemagglutinin
What are virulence factors
- refer to the properties of bacterial gene products that enable a microorganism to cause disease
Isotypes ____ and ___ are the most efficient opsonins for promoting phagocytosis via high-affinity FcgammaRI (CD64)
- IgG1
- IgG3
A polymorphism in the ______ gene has been linked to susceptibility to the autoimmune disease systemic lupus erythrematosus in humans
- FcgammaRIIB gene
- (this makes sense because they are not able to activate the inhibitory (FcgammaRIIB) thus they overproduce antibodies
What is antibody-dependent cell-mediated cytotoxicity (ADCC)
- Ab of certain IgG subclasses bind ot infected host cells, and the Fc regions of the bound Ab are recognized by an FcgammaRIII on NK cells
- The NK cells are activated and kill Ab-coated cells
Worms can be killed by a toxic cationic protein, known as the _______, present in the granules of eosinophils
Major basic protein (MBP)
FcepsilonRI binds to ____ and is found on
- Monomeric IgE
- Found on Mast cells, Basophils, and Eosinophils
- thus needed to fight parasitic infection
The classical pathway is initiated by binding of the ____ to ___ or ___ molecules that bound Ag
The classical pathway is initiated by binding of the C1 to IgG or IgM molecules that bound Ag
Among the various IgG subclasses, ____ and ____ are most efficient activators of complement
IgG3 and IgG1
C1 is composed of what 3 subunits
- C1q, C1r, and C1s
- The C1q binds to Ab, whereas C1r and C1s are proteases