Antibodies and complements Flashcards
what is the difference b/w the primary and secondary response to an antigen
secondary is much more powerful and faster
basis of vaccinations*
what are the 3 basic functions of Ab ?
1 - opsonization (tag/label)
2 - complement fixation (once activated will destroy)
3 - direct nuetralization (bind and remove toxins)
what is the major isotype of immunglobins in blood serum ?
IgG
basic functions of IgG
- neonatal immunity
- immunological memory
what is the basic structure of ALL Ab ?
Y shaped
Function of IgD and what percentage of blood serum does it make up ?
B cell receptor, so major Ig at surface of B cells
-rare in blood <1%
How much of IgE is in blood and what is its function
Scarce
- found on surface of basophils and mast cells
- kills lg. parasites
- part of allergy response
what purpose do the multiple granules cells w/in mast cells serve ?
act like torpedos to attack parasites
what is the structure of IgA and where is it found
- dimer
- secreted by saliva in oral cavity
what is the structure of IgM and why does this make it unique
-pentamer, allows it to sniff out antigens the fastest cuz so many arms making it first secreted Ab to respond
what Ig can serve as B cell receptors ?
IgD
IgM
what is the general role/significance of the complement system in immune response
complete the role of Ab
how do complement fragments become active ?
- Start as proenzymes (inactive) w/masked active sites
- proteolytic cleavage unmasks exposing active site
- result in “active” fragments of complement molecules
what is the central component of complements
C3
what are known as the late components
C5-C9 (formation of the MAC)
what are the 3 principle functions of the complement system
1 - opsonization and cell activation
2 - chemotaxis
3 - lysis of target cells
what is the difference in the complement systems functions of 1) opsonization and 2) chemotaxis
1) opsonization - complement fragments tag Ag for phagocytosis “eat me”
2) chemotaxis - complement fragements stimulate immune cells to move towards infection “find me”
The complement systems ability to lyse target cells requires the assembly of what ?
membrane attack complex (MAC)
what specific complement family members perform opsonization
opsonization - IC3b, C3b, C4b,
what specific complement family member perform chemotaxiss
chemotaxis - C3a, C5a
what specific family member of the complement system performs cell-mediated cytolysis
C5b
the classical activating pathway for the complement system is part of the _____ immune response whereas the alternate pathway is part of the _____.
- adaptive (needs Ag-Ab complex)
- innate (only need Ag)
Explain the alternative activation pathway of the complement system
1 - cleave C3 = C3a and C3b
2 - in presence of Ag then C3b binds factor B = C3bB
3 - factor D cleaves C3bB = C3bBb ( C3 convertase)
4 - C3 convertase catalyzes more C3 and start over
what is C3 convertase in the alternative pathway and what is its role
C3bBb
-catalyzes tons of C3 cleavage which engages more complement framents to become activated
