Lecture 6 Flashcards
(17 cards)
Which cell types have humoral immunity vs cell-mediated immunity?
humoral immunity: B cell
cell-mediated immunity: T cell
Which cell type produces antibodies?
B-cells
How does B-cell activation happen? What happens?
Activated by T cells, promotes differentiation into plasma cells (enhanced antibody producing cells)
What is the constant region of the antibody?
Constant Fc Region signals to innate immune cells
What happens in neutralization?
antibody blocks binding to virus receptor, can block fusion event
How do antibodies activate degranulation?
Activated mast cell has multivalent antigen crosslinking a bound IgE antibody, causing release of granule contents
Fc receptors on NK cells recognize bound antibody, crosslinking of Fc receptors signals NK cell to kill target cell
How does the Lectin Pathway work?
mannose-binding lectin (MBL) and ficolins recognize, bind carbs on pathogen surface
MASP1 undergoes conformation change, cleaves MASP2 –> C4 and C2 –> C4a/C4b, C2a/C2b –> C3 convertase takes C4b2a complex and turns to C3 –> C3a/C3b
What is CRD?
carbohydrate recognition domain
What is MASP?
MBL-associated serine protease (enzyme that cleaves peptide bonds)
What does C3a do?
inducer of vascular permeability
How does the classical pathway differ from the Lectin pathway?
Instead of MASP-1 –> MASP-2, it goes C1r –> C1s
How does the alternative pathway differ?
does not require microbial recognition to initiate
C3b deposited, binds factor B, bound B is cleaved by factor D into Ba and Bb –> C3bBb is a C3 convertase –> many C3a and C3b
Why is the alternative pathway dangerous?
can initiate on host cell membrane
What is opsonization?
coating a pathogen with complement or antibodies so that it can be more readily taken and destroyed by phagocytic cells
What does C5a do?
inducer of vascular permeability
What does C5 convertase do?
Takes C3b and friends and turns into C5 –> C5a/C5b
What is the membrane attack complex?
C5b binds C6 and C7
C5b67 complexes bind to membrane by hydrophobic site on C7
C8 binds to complex and inserts into membrane, induces polymerization of C9
10-16 C9 bind, form a pore
