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Antibodies
Igietseme
37
Biology
Professional
08/28/2008

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Term
Antibody
Definition

An immunoglobin that binds a specific antigen.

Term
Antigen vs. Immunogen
Definition
  • Antigen(Ag): A substance that can be bound by an antibody.
  • Immunogen: An antigen that induces an immune response.
Term
What is an Immune Complex? How is it held together?
Definition
  • Product formed when Antigen(Ag)-Antibody(Ab) bind.
  • H-Bonds and Hydrophobic interactions
Term
Kaff (or simple affinity) measures:
Definition
  • Tightness of binding
  • Stability of the Ag-Ab complex
  • with time, affinity increases

[Ag-Ab]/[Ag][Ab}

Term
Significance of Ag-Ab binding
Definition
  • First step in host's defense function
  • High affinity Abs are better in vivo for host defense. (they can quickly bind)
  • May lead to tissue destruction/disease. (Vasculitis, Glumerulonephritis
Term
What are two common techniques used to test for antibodies?
Definition

ELISA

Western Blot

Term
How is antibody measurement as a diagnostic tool?
Definition
  • Exposure to infectious agent (HIV, anthrax)
  • Evidence of Immunity
  • Certain autoimmune diseases
  • Allergic reactions to substances
  • Immunodeficiency
  • Malignant Lymphoid diseases (Too much antibodies)
Term
Antibody dependent cellular cytotoxicity (ADCC)
Definition
using NK killer cells
Term
How are the polypeptide chains of the Immunoglobins designated?
Definition
  • 4 polypeptide chains. 2 Light. 2 Heavy
  • The L chains are either 2 κ(kappa) or 2 λ(lambda). NEVER one of each

 

Term
What is the neck region of the immunoglobin(Ig)?
Definition
  • Di-Sulfide bonds that connect the 2 Heavy chains together.
  • Allows movement of binding sites.

 

Term
What is the function of the different domains/regions of immunoglobins (Ig)?
Definition
stability/function
Term
What does Papain do to Immunoglobins?
Definition
  • It cleaves 2 seperate FAB fragments away from the Fc fragment.
Term
What does Pepsin do to immunoglobins?
Definition
  • In generates 2 FAB (antigen binding sites) as one unit.
  • Also slices up the Fc into a bunch of pieces.
  • Important for research.
Term
Hypervariable(HV) regions of immunoglobins:
Definition
  • Also called Complementary Determining regions.
  • Sites of contact with antigen (Ag)
Term
What are the subclasses of IgA and IgG?
Definition
  • IgA: (IgA1, IgA2)
  • IgG: (IgG1, IgG2, IgG3, IgG4)
Term
What determines the different classes of Immunoglobins?
Definition
  • The type of amino acids in the Constant domains of the H chain.
Term
What joins two imunoglobins?
Definition
J chains
Term
How does IgM and IgA benefit from becoming multimers?
Definition
  • Increase valency
  • Increase binding capacity
Term
Which immunoglobin has the highest serum concentration and lasts the longest?
Definition
IgG
Term
Which Immunoglobin is found binding to Mast cells?
Definition
IgE
Term
Which Immunoglobin is involved in placenta transfers?
Definition
IgG
Term
Which Human chromosomes code for immunoglobins?
Definition
2, 22, 14
Term
leader sequence
Definition
= signal sequence
Term
How are the gremline genes of the Light κ or λ chains organized?
Definition
  • ≥50 V genes and about 5 J genes code for the Variable domains.
  • A single C gene codes for the Constant domains.
Term
How are the germine genes of the Heavy chain organized?
Definition
  • Alot of V,J, and D(for Diversity) genes encode for the Variable domain.
  • Single C gene codes for H chain class and subclass.
Term
What is the first Immunoglobin usually made? Where does it go?
Definition

IgM (sometimes IgD, depending on alternative splicing) 

It hangs out on the surface of B-cells waiting to intereact with an antigen.

Term
How many gene rearrangments must the Ig go through to produce a plasma cell?
Definition

2

The first one makes IgM(or IgD) which sits on the surface of the mature B-cell.

After contact with an antigen the Ig can change constant regions if needed. The B cell divides and activates into Plasma cells.

Term
What is the first Ig to be secreted by the B cell?
Definition
IgM
Term

What is the difference between Secreted Ig(sIg) and Membrane Ig(mIg)

Definition
  • The carboxyl(Fc) end of the Heavy chain
  • Due to alternate splicing the mIg has a transmembrane portion that contains a small extra exon at the 3' end of the last constant domain.
Term
Class switching or Isotype switch
Definition
  • Going from Igm(or IgD) to IgG, IgA, IgE
  • Involves  second gene rearrangement/recombination event.
Term
Swithc circle
Definition
  • The part of the mRNA taken out during second gene rearrangement.
Term
Clonal Selection theory and Basis of Specofoc Immunity
Definition
  • Theory explains Ab specificity during immune response

 

Term
Junctional Diversity
Definition
  • Each V,D, and J gene has many amino acid sequences.
  • Any one of those sequences can be the last one transcribed and thus create even more diversity.
Term
Major Histocompatibility Complex (MHC)
Definition

also called HLA (human leukocyte Antigens)

  • Class I: All somatic. Controls CD8 T cells
  • Class II: Controls CD4 cells
  • Transplantation: control graft rejection.
Term
T cell Receptor
Definition
  • receptor for antigen binding by T cell.
  • 2 types: αβ & γδ
  • Gene rearrangement similiar to Ig
  • Only binds Ag that is already attached to a MHC
Term
How does mutation affect TcR diversity?
Definition
Unlike Igs, somatic mutation does not contribute to TcR diversity.
Term

What are antibodies' effector functions in host defense?

Definition
  • Neutralization of infectious agents or toxins
  • Immune phagocytosis
  • Complement activation
  • Antibody dependent cellular cytotoxicity (ADCC) using NK cells
  • Enhancement of Ag presentation, T cell activation & Immune reactivity.
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