Immunoglobulin Structure Lecture 4 Flashcards
How do Ig classes differ?
constant region in the heavy chain
What is the structure of IgM?
pentameric IgM
What is the secretory structure of IgA?
Dimeric
What is the secretory component of the IgA?
protective hinge area where the dimer might be cleaved
What is the major immunoglobin in blood?
IgG
Where do you find IgD immunoglobins?
on surface of b-cells
What is a baby born with?
Maternal IgG
What does cross linking of IgE on mast cells lead to?
Degranulation, histamine and other substances released that cause allergic reactions
*must be crosslinked
What are 3 methods by which antibodies mediate humoral immunity?
- Neutralization-prevent bacterial adhesion
- Opsonization-antibody promotes phagocytosis
- Complement Activation-antibody activates complement, enhances opsonization and lyses bacteria
IgM, primary or secondary response?
Primary
IgG, primary or secondary response?
Secondary
IgD usually membrane form or plasma form?
membrane
What does aggregation of immunoglobulin on bacterial surface allow for?
- cross linking of Fc receptors
- activation of macrophage
- phagocytosis and destruction of bacterium
What is a crucial time for babies, because maternal IgG antibody is almost gone and they havent started making much of its own IgG?
3-9 months
Is a vaccine as good as having the disease in terms of half life length of serum antibody?
NO
Polyclonal vs. Monoclonal antibodies
Polyclonal: multiple antibodies, directed against different epitopes made by separate clones of B-lymphocytes
ex: IVIG (intravenous immunoglobin)treatment for inflammatory disease
Monoclonal: single B-cells that make a single kind of antibody, can be immortilized in vitro and used as a continual source of a specific monoclonal antibody
ex: tumor specific antibodies to treat cancer
What type of rearrangement do Ig genes undergo?
somatic DNA recombination
What exons encode the variable region in the light chain?
V and J exons
What exon encodes the constant region in the light chain?
a C exon
What exons encode the variable region in the heavy chain?
V, D, J exons
What exon encodes the constant region of the heavy chain?
multiple C exons
membrane associated: transmembrane and cytoplasmic
Where are Ig genes only expressed?
B-lineage cells
what is the order of Ig gene rearrangement
light chain
heavy chain
- heavy chain DJ
- heavy chain VDJ (critical control point)
- light chain VJ
