Immunoglobin Isotypes

Question 1

IgA

Answer 1

• Product of class switching, plasma cell
• Produced in the GI tract in peyers patches–> secreted as DIMER, combined with secretory component from epithelial cells that allows the IgA to traverse epithelial cells (transscytosis) into the gut –> protects against gut infections
  Function/:
• neutralizes antigen only (inhibit binding)
  ** exists as a monomer in plasma
  ** secreted in saliva, tears, mucus, and boobie milk

Question 2

IgM

Answer 2

• Immediate response antigen- surface on B cells
  –> monomer on B cells, pentamer when secreted (enables avid binding of the antigen while the humoral response evolves)
  Function;
• Fixes complement
• do not cross the placenta

Question 3

IgD

Answer 3

• Surface of B cells and in serum

- Function unknown

Question 4

IgE

Answer 4

• From class switching, plasma cell
• Secreted
• Binds mast cells and basophils -> crosss linkes when allergen binds –> results in release of hypersensitivity modulators (TYPE 1 HYPERSENSITIVITY RXN)
• Mediates immunity to worms via Major basic protein release from eosinophils when binds

Question 5

Thymus Independent antigens

Answer 5

• do not have a peptide component- therefore cannot be presented via MHC
• ** VACCINES NEED PEPTIDE ADJUVANT

Question 6

Thymus dependent antigens

Answer 6

• antigens that have a peptide component and can be presented via MHC- activate class switching and memory

Question 7

IgG

Answer 7

• product of class switching- plasma cell
  -Main antibody in DELAYED response to antigen
  Functions:
• Fix complement
• neutralize
• opsonization
  ** crosses the placenta (passive immunity to the infants)