Defense against extracellular pathogens Flashcards
How many different isotopes of immunoglobulin are there
9
What are the two regions on immunoglobulin
Fab
Fc
Which region on immunoglobulin binds to the antigen
Which region points away from the antigen
Fab
Fc
Which isotopes trigger complement proteins
IgM
IgG
Which isotopes trigger phagocyte binding
IgG
IgA
Which isotopes trigger mast cell binding
IgE
What is the advantage of having different isotopes
Different types of defensive processes activated because of different antibodies
When are complement proteins active
Activated in presence of infeciton
What active complement proteins does C3 (inactive complement protein) make
C3a + C3b
Reaction to show inactive C3 and what it becomes
C3—-> C3a+ C3b
What enzyme activates C3 into active complement proteins
C3 convertase
Names of the 3 reactions that produce C3 convertase
- Classical pathway
- Mb Lectin pathway
- Alternative pathway
What happens in the classical pathway
1) Immunoglobulin (IgG) binds to antigen and the Fc region points away from it
2) Binding of C1q triggers activation of C1s and C1r which causes them to be split into fragments
3) Split into C4 and C2
4) C4 forms C4a and C4b, C2 forms C2a and C2b
5) C4b and C2a combine to form C4b2a
6) C4b2a is C3 convertase
What happens in the Mb lectin pathway
1) Manose binding lectin binds to manose residues in microbial carbs
2) Activation of MASP 1 & MASP2 (which are bits attached to the top of mans binding lectin0
3) MASP1 & MASP2 activate C4 and C2
4) C4 and C2 split into C4a, C4b, C2a, and C2b
5) C4b and C2a combine to form C4b2a which is C3 convertase
What is the Alternative pathway
1) C3b binds to microbial surfaces
2) Bb binds to it
3) P protein also binds to it
4) this all makes- C3bBbP (which is C3 convertase)
How to make C5 convertase
C3 convertase+ C3b
Reaction to show what C5 is activated to using C5 convertase
C5—–> C5a+C5b
What do C3a and C5a do
- activate mast cells
- Recruit neutrophils
What does C5b take part in
Membrane attack pathway which using membrane attack complex (causes cell lysis)
Whats the membrane attack complex and pathway
1) C5b sticks to lipid membranes of microbes
2) C6 and C7 bind to C5b
3) C8 inserts into lipid membrane
4) Lots of C9 make their way over
5) hole formed in lipid membrane
What are opsonins
Bind to microbes and encourages binding of microbe to phagocyte
How are opsonins made
1) bacteria induce macrophages which produce IL-6
2) IL6 goes to liver
3) Liver releases active phase proteins such as C reactive protein and Maman-binding lectin
4) These act as opsonins which bind to microbes and encourages binding of microbe to phagocyte
Two types of opsonins
C reactive protein
Maman-binding lectin
What are other types of opsonins and how do these work
1) Microbe bound to antibody
2) Complement proteins also bound to microbe
3) FC receptors on phagocyte binds to Fc on antibody
4) CR binds to the C3b (complement protein on microbe)
