MIMG 185A Lecture Notes - Lecture 3: Immunoglobulin A, Phagocytosis, Pentamer
5 May 2018
School
Course
Professor
Separating*compounds*based*on*their*properties*
○
Column*Chromatography:
-
Peaks*look*different*depending*on*enzyme*digest*
○
Can*graph*eluant*fraction*against*absorbance
-
Separating*Compounds*
Digest*proteins*with*proteases
-
Analyze*by*electrophoresis,*chromatography
-
Used*to*determine*what*parts*of*the*antibody*were*the*same*and*which*were*
different*
-
Filled*up*spots*correspond*to*regions*that*consistent*across*antibodies
-
2D*Peptide*Mapping
Two*heavy*and*two*light*chains*
-
Variability*due*to*random*addition*or*deletion*of*nucleotides
§
CDRs*-hypervariable*regions*that*are*the*primary*area*of*contact*
between*the*Ab*and*antigen*
○
Determine*the*affinity*of*the*Ab*
○
Recognition/binding*specificity*conferred*by*Fab*end/variable*region/CDRs
-
5*classes*of*antibodies:*IgM,*IgD,*IgA,*IgG,*IgE
○
Effector*function*conferred*by*the*constant*region*(Fc)
-
Antibody*Structure
Typically*the*antigen*fits*into*a*pocket*on*the*antibody
-
E.g.*HIV
○
Sometimes*the*antibody*can*protrude*and*fit*into*a*pocket*in*the*antigen
-
Antibody-Antigen*Binding*
IgG*antigen*binding*site*typically*has*high*affinity*for*its*target
○
Affinity:*strength*of*a*single*antibody-antigen*interaction
-
IgM*typically*has*low*affinity*antigen*binding*sites*but*there*are*ten*of*
them*(pentamer)*so*avidity*is*high
○
Avidity:*strength*of*all*interactions*combined
-
Affinity*vs*Avidity
Epitope*-the*part*of*the*antigen*that*the*antibody*binds*
-
Polyclonal*response
○
Can*have*two*different*antibodies*that*bind*to*the*same*antigen*but*different*
epitopes*
-
Epitope*vs*Antigen*
Agglutination
○
Neutralization
○
Precipitation*
○
Keeps*antigens*in*the*serum*and*prevent*them*from*infecting*cells*
-
Opsonization*-facilitates*phagocytosis*by*macrophages*
-
Antibody*Functions*
Facilitated*by*antibodies*
-
Bacterial* lysis*
-
Complement*System
Used*to*skew*immune*response*in*one*direction*to*target*the*specific*
immunogen*
-
Different*immune*cells*are*better*at*dealing*with*certain*pathogens*
-
Cytokines*in*class*switching*
Determines*function,*localization,*and*lifetime*in*serum*
-
Important*for*entry*to*different*tissues*
§
Typically*a*monomer
○
Only*Ab*that*can*cross*the*placenta
○
IgG*
-
Only*Ab*that*can*enter*the*gut*
○
IgA
-
Antibody*classes/isotypes
Immune*Response*Timeline*
Continues*throughout*the*immune*response
○
Innate*response*occurs*almost*immediately*(within*minutes)
-
IgM*secreting*cells*increase*in*number*and*continue*secreting*IgM*
-
E.g.*delayed*increase*in*IgG*(secondary*response*has*quicker*increase* in*
IgG*upon*infection*due*to*presence*of*plasma*cells*in*serum)
○
Class*switching*has*a*delay*
-
Start*from*low*number*of*cells
○
Activated*within*hours*but*takes*days*to*be*in*full*effect*
○
T*cell* response*is*also*delayed*
-
Primary*Response
W2#Discussion#4.11.18
Wednesday,* April*11,*2018
12:24*PM
Document Summary
Used to determine what parts of the antibody were the same and which were different. Filled up spots correspond to regions that consistent across antibodies. Cdrs - hypervariable regions that are the primary area of contact between the ab and antigen. Variability due to random addition or deletion of nucleotides. Effector function conferred by the constant region (fc) 5 classes of antibodies: igm, igd, iga, igg, ige. Typically the antigen fits into a pocket on the antibody. Sometimes the antibody can protrude and fit into a pocket in the antigen. Igg antigen binding site typically has high affinity for its target. Igm typically has low affinity antigen binding sites but there are ten of them (pentamer) so avidity is high. Epitope - the part of the antigen that the antibody binds. Can have two different antibodies that bind to the same antigen but different epitopes. Keeps antigens in the serum and prevent them from infecting cells.
