Antibodies Flashcards
Graves Disease
Antibodies to TSH, can cross placental barrier
Allergies
Fc of IgE binds to mast cells and induces histamine/contents release
Regulation of Transplant Rejection
Can use Abs to downregulate T cell response responsible for transplant rejection
Ab Cancer Treatment
Can target Abs w/ toxin to specific cell markers, like HER2
3 Serum Electrophoresis Results for Igs
Faint Ig bands - fine
Strong for all Ig bands - infection
Strong for 1 Ig band - tumor of plasma cells making 1 Ig
Combining Sites (2)
End terminus of LC and HC where Ag binds; requires both HC and LC to come together/bind Ag
2 Kinds of LCs (ratios and important point)
About 60:40 Kappa:Lambda
So if you saw only lambdas, know there’s a tumor producing lambda LCs
Hypervariable Regions (2)
3 spots on V regions on each HC and LC that make up combining sites, accounting for Ag-binding diversity
Variability Calculation Def
of AAs found at a given position/frequency of the most common AAs at that position
Variability in Framework Regions
Still some so that superantigens can’t bind to EVERYTHING
Average Size of Ag Combining Site (2)
6 saccharides or 4 AAs
Ig Isotypes
Different region genes encode for different HC classes (effector function)
IgM Notable Structure
Pentamer
IgA Notable Structure
Dimer
IgG Notable Feature (2)
Passes through placenta, so can cause problem’s w/ Grave’s disease but also transfer maternal immunity (so it’s the only one that doesn’t constantly increase through early life - starts off high, then drops and then steadily increases)
IgA Production Areas
Lungs/intestines
IgM Notable Feature
1st Ab made
Ab Deficiency Time of Detection
Around 6 months
Main 2 Points About Abs
Need HC and LC to make combining site for Ag binding
Effector function is in the HC
Regions of Recombination for Igs
HCs have VDJ and LCs have VJ
Ways to Separate Recomb for Different Chains (4)
All HC genes on 1 chrom, all kappa LC on a different chrome, and lambda LC on different chrom, and TCR chains (except alpha/delta) on different chroms
HC Recombination
D and J recomb’d and moved adjacent to each other, then to V, then C
LC Recombination
V and J recomb’d and moved adjacent toe ach other, then C
Rag1/Rag2
Recombination activation endonucleases only in B and T cell precursors
Somatic Hypermutation (3)
Continued mutations in hypervariable regions of B cells catalyzed by AID and selected for by Ag for stronger Ag binding
Switch Recombination
Once Ig expressed and Ag selected for correct binding in B cells, AID catalyzes to switch the HCs for different effector functions
Activation-Induced Cytidine Deaminase
Enzyme in B cells reponsible for somatic hypermutation and switch recombination
3 Trends of Switch Memory B Cells/Vaccine Response (& major point)
Percentages of switch memory cells increase in young but not elderly as much after vaccination Percentage of switched memory B cells correlates w/ vaccine response AID positively correlated w/ vaccine response *Class switch important because your higher affinity Ab can have better effector function. so vaccine response increases with class switching
How to Target Ig for Secretion or Membrane Bound
Differential mRNA splicing
How to Get IgD and IgM on Cell Surface at Same Time
Keep same VDJ (already specified towards Ag) and just splice mRNA differently to have Cmu or Cdelta
Antibody Affinity
Can calculate like any other rxns, reversible and K = [AbAg]/([Ag][Ab])
Avidity (3 long)
Multivalency, multiple binding sites on both Ag and Ab mean actually binding doesn’t follow thermodynamic equation so avidity is how well it actually binds
Greatly increases ability to bind uninterrupted over long period of time bc if one binding site deattaches, other one is still on
Even if IgM has lower affinity than another Ig, may actually bind better bc has higher avidity from 10 binding sites
Primary and Secondary Interactions of Ab and Ag
Primary is fast rxn just controlled by diffusion
Secondary is slow reaction that results in cross linking and precipitation
Immunoprecipitation and Ab/Ag Concentrations
Too much Ab: Epitopes bound but still small complex, nothing else for Abs to bind to
Too much Ag: All Abs bound, but to just 2 epitopes each. Small complex
Equal: Formation of a large precipitate lattice
7 Clinical Uses for Abs (& examples)
Detection of Viral Antigens (HIV testing)
Detection of Cancer Antigens (PSA, prostate)
Typing of Tissues for Transplantation (see relatedness and likelihood of rejection)
Typing of Blood for Transfusion
Pregnancy Testing
Anti-Cell Therapy - Rituximab stops B lymphocyte tumors
Detection of Autoantibodies (like SLE on dsDNA)
Flow Cytometry (2)
Tag target of interest w/ fluorescent antibodies, it counts cells in blood individually and gives reading on #
Can be used for lambda/kappa LC comparisons or T cell counts for HIV
Enzyme Linked Immunosorbent Assay (ELISA) (reason and process)
To see if person has Abs to something
Put target of interest on plate, add pt Ab, add ezyme-linked secondary Ab to tag those Abs to see if it bound and will turn medium from clear to colored
Direct Coombs Test (reason and process)
To test autoimmunity to RBCs
Take blood sample and wash RBCs, then add secondary antibody and crosslinking will cause
“pallet” of RBCs
Agglutination
Measuring Ab to RBC in hemolytic anemia
Indirect Coombs Test (reason and process)
To test blood recipient match
Take recipient serum, add to donor blood, and do direct coombs test to see if Abs bind
