Lymphocytes II Flashcards
T cell activation
MHC II Ag - to CD4 T cell
MHC I Ag - to CD8 T cell
costimulation - B7 and CD28
requires 2 signals**
B cell activation
B cell receptor mediated endocytosis -foreign antigen on MHC II and recognized by TCR on CD4 T cell - signal 1
CD40 on B cell - bind CD40L on Th cell - signal 2
CD4 T cell - secrete cytokine - determine Ig class switch of B cell
antibody structure
Fab - variable - L and H chain region
Fc - IgM and IgG - fixe complement - close to hinge
heavy cahin - Fc and Fab regions
light chain - only Fab region
Fab regions
antigen binding
antibody diversity
rearrangement VJ and VDJ genes
somatic hypermutation
Fc region
constant
carboxy terminal
carb side chain
determine isotype
mature B cells
express IgM and IgD
CD40 induce isotype switch - to IgA, IgE, and IgG
IgG
main Ab - delayed response to antigen
most abundant in serum
fix complement
cross placenta
infant - passive immunity
IgA
mucous membrane defense
does not fix complement
monomer in circulation
dimer when secreted
produced in GI tract - peyers patches
most produced - but low in serum
released into tears, saliva, mucus, breast milk
IgA
IgM
immediate response to antigen
fix complement
does not cross placenta
monomer on B cell
pentamer when secreted
IgE
bind mast cell and basophil
cross linked when exposed to allergen
type I hypersensitivity
thymus independent Ags
Ag lack peptide component cannot be presented by MHC to T cells
weak or nonimmunogenic
vaccine - require booster and adjuvant
thymus dependent Ags
antigen with protein component
immuno memory occur
-bc B cell and CD4 T cell CD40 interaction
acute phase reactants
induced by IL-6 mainly
signify inflammatory process
C-RP
measure of inflammation
ferritin
bind and sequester iron
acute phase reactant
fibrinogen
coag factor
acute phase reactant
hepcidin
prevent release of iron bound by ferritin
acute phase reactant
serum amyloid A
acute phase reactant
prolonged elevation = amyloidosis
class complement pathway
IgM
IgG
alternative complement pathway
microbe surface molecule
lectin complement pathway
mannose -other sugars on microbe surface
anaphylaxins
C3a
C4a
C5a
opzonin
C3b
MAC complex
C5-9
neutrophil chemotaxis
C5a
inhibitors of complement
so don’t attack self cells
CD55
C1 esterase inhibitor
C1 esterase inhibitor deficiency
hereditary angioedema
CI - ACE Is
C3 deficiency
risk severe recurrent pyogenic sinus and resp infections
susceptible to type III HS
C5-9 deficiency
susceptible to neisseria infection
DAF deficiency
complement mediated lysis of RBCs and paroxysmal nocturnal hemoglobinuria
C3 convertase of alternative
C3bBb
C3 converatase of lectin and classic
C4b2b
C3 convertase
cleave C3
to C3b and C3a
C3a - anaphylatoxin
C3b - helps to form C5 convertases
cleaves C5b and C5a
C5b - activate MAC complex
C5a - attract neutrophils
