Antibodies Flashcards
Immunogenicity:
The capacity to induce an immune response.
Immunogenicity requires (3):
- Be foreign to immunized host.
- Possess a certain molecular weight.
- Possess a certain degree of molecular complexity.
Antigenicity:
The ability to bind with antibodies or cells of the immune system.
Plasma cells make antibody in:
Germinal centers (white pulp of spleen, cortex of lymph nodes or in MALT).
Somatic hypermutation:
Slight mutation in the rearranged genome give rise to slight variations in the ability of the antibody to bind. Sometimes it is a change in affinity.
The recombination events in B-cells to produce antibodies are mediated by:
V(D)J recombinase
- RAG 1 and RAG2 genes
Antibody that functions in neutralization:
IgG, IgA
Antibody that functions in opsonization:
IgG1
Antibody that functions in sensitization for killing by NK cells:
IgG1, IgG3
Antibody that functions in sensitization of mast cells:
IgE
Antibody that functions in sensitization of basophils:
IgE
Antibody that activates compliment:
IgM, IgG3
Antibody able to cross epithelium:
IgA (dimer)
Antibody able to cross placenta:
IgG1
Antibody able to diffuse into extravascular sites:
IgG
IgM
- Pentamer.
- First antibody made in the primary response.
- Fixes compliment, does NOT mediate phagocytosis or cross placenta.
IgA
- Monomer (majority) or dimer.
- Major immunoglobulin found in seromucous secretions.
- Fixes complement and mediates phagocytosis (monomer).
IgG
- Monomer.
- 4 subclasses.
- Characterize the secondary antibody response.
- Can fix compliment.
- IgG1 and IgG3 can mediate phagocytosis
- Can cross placenta
IgE
- Scarce in plasma.
- Found on surface of mast cells and basophils.
- Response to parasites.
- Common in allergic states.
- Shortest half life (2 days).
- Mediates allergic reactions.
