Antibodies Flashcards
(17 cards)
how do antibodies bind to antigens
epitope on equitope bind to Fab
avidity - number of bonds
affinity - strength of 1 bond
Hinge region - 2 binding sites
consequences of Ab binding
neutralisation agglutination opsonisation complement activation bind to phagocytes by Fc receptors
structure and function of IgG
gamma inflammation most abundant monomer actively transported - placenta small - in blood ane EC fluid activator classical complement pathway 1 and 3
structure and function of IgA
alpha
monomer in blood
dimer in secretions - joining channel
protect mucosal surface
structure and function of IgM
Big - pentameric - monomer joined by J chain primary Ab response mew agglutination stop movement and entry into cells high avidity activate complement
structure and function of IgE
allergy low levels parasites bind Fc mast and basophils cross linking triggers mast cell activation and histamine release. found below epithelia
structure and function of IgD
delta
expressed early in B cell development
involved in B cell activation
Forces between epitope and Ab
hydrogen ionic hydrophobic van der walls individually weak - collectively strong
definition of affinity
strength of total noncovalent interactions between single antigen binding site and single epitope
definition of avidity
overall strength of multiple interactions between Ab with multiple binding sites with multiple epitopes
comparison between affinity and avidity
better measure of capacity than affinity
equation for association constant of affinity
Ab + Ag (eq arrow) Ab-Ag
K=[Ab-Ag]/[free Ab][free Ag]
what is Ab cross reactivity, and examples
Ab recognise different antigen than what specific for
vaccination cowpox
blood types/microbes
what re the subclasses of IgG and IgA
IgG1,2,3,4
IgA 1, 2
different functions and locations
function of Abs
target infective organisms recruit effector mechanisms passive immunity diagnosis passive therapy monoclonal Ab - cancer diagnostics and research
formation of secretory IgA
bind to Ig receptor
vesicle
enzymatic cleavage
secreted with secretory component - prevent degradation
Outline structure of immunoglobulin
heavy and light chain
light chain always kapa
heavy GAMED
joined by disulphide bridges
Fc - bit that is constant in all - crystallises, receptor for Fc on phagocytes
Fab - variable - binds to the antigens
hinge region - flexible - bind to 2 antigens
