lecture 5: innate immunity (part 2) Flashcards
what is the early step 1 of complement activation
formation of C3 convertase complexes that produce C3a and C3b which trigger inflammation and opsonizes microbes
what is the early step 2 of complement activation
formation of C5 convertase complexes that produce C5a and C5b which perpetuate inflammation and initiates the late steps
what are the late steps of complement activation
formation of membrane attack complexes which form holes in microbial membranes
what does C3 convertase do
cleaves C3 producing C3a fragment and C3b fragment
what does the C3a fragment do
stimulates inflammation by acting as a chemoattractant for neutrophils
what does the C3b fragment do
becomes covalently attached to the microbial surface and serves as an opsonin to promote phagocytosis of the microbes
what does C3 convertase binding to the C3b fragment form
a protease fragment called C5 convertase
what does the C5a fragment do
it is a very potent chemoattractant that also induces changes in the permeability of blood vessels
what does C5b do
it is attached to bacterial membrane that initiates the formation of a complex of C6, C7, C8, and C9 complement proteins called the membrane attack complex
what doe multiple MACs cause
bacterial leak and lysis
what is the function of C4
C4b covalently binds to surface of microbe or cell where antibody is bound and complement is activated. Cb4 binds to C2 for cleavage by C1s. C4a stimulates inflammation
what is the function of C2
C2a is a serene protease functioning as an active enzyme of C3 and C5 convertases
what does properdin do
stabilizes protein: protein interactions during the alternative complement pathway process
what portion of the Ab does Cl1 bind to in the classical pathway
Fc portion
define MBL
soluble PRR that binds carbs with terminal mannose and enhance phagocytosis of microbes
what is the major function of SP-A and SP-D
maintain the ability of lungs to expand and as mediators of innate immune response. Also act as opsonins, facilitating phagocytosis by alveolar macrophages. can directly inhibit bacterial growth. may directly activate macrophages.
what stimuli from T lymphocytes are likely to activate macrophages
CD40 ligand and IFN-gamma
what is the principal cell source for TNF
macropages, T cells
what is the principal cell source for IL-1
macrophages, endothelial cells, some epithelial cells
what is the principal cell source of chemokines
macrophages, DCs, endothelial cells, T lymphocytes, fibroblasts, platelets
what is the principal cell source of IL-12
Dendritic cells, macrophages
what is the principal cell source of IFN-gamma
NK cells, T lymphocytes
what is the principal cell source for IFN-alpha
DCs, macrophages
what is the principal cell source for IFN-beta
fibroblasts
