Card Set Information

2010-03-31 17:07:53
2 2_Immune_

Antibody structure and function
Show Answers:

  1. Q: What are the two regions of an antibody structure and what terminal are they (N or C terminal)?
    A: FAB region is the N terminal (bound with light chain), and Fc region (C term) in membrane if membrane bound.
  2. Q: What holds the different chains of an antibody structure together?
    A: Disulfide bonds
  3. Q: What are the 5 different antibody classes?
    A: Alpha=IgA; Delta=IgD; Epsilon=IgE; Gamma=IgG; Mu=IgM
  4. Q: What are the two types of light chain molecules of the antibody and which is more prevalent?
    A: Kappa and Lambda 2:1 ratio in serum (more kappa)
  5. Q: What region of an antibody molecule determines the specificity of antigen binding?
    A: The Hypervariable regions.
  6. Q: What does CDR stand for and what is it?
    A: Complementary Determining Regions. They are complementary to the bound antigen. The most hypervariable regions.
  7. Q: How many CD (complemenary determining) regions are in the variable region and how many amino acids make these regions?
    A: 3 CD regions are made up of approx. 10 aa's on each of the heavy and light chains.
  8. Q: How many constant regions do Ig's have?
    A: M and E have 4. G, A and D have 3.
  9. Q: 2 enzymes were listed that can split the antibody, one before and one after the disulfide bond. What are the names of the two enzymes and where do they cut?
    A: Papain splits before (FAB side) disulfide (A comes first)(this gives 2 FAB molecules. Pepsin splits after giving one molecule with 2 FAB regions.
  10. Q: What is the normal conformation of the immunoglobulins A,D,E,G, & M?
    A: A can be a dimmer. M is a pentamer. And the rest are monomers.
  11. Q: What tissue are the immunoglobulins found in?
    A: 80% of M is in blood. G found in fluids, tissues, and blood. D is not secreted (on B cells).
  12. Q: List some functions of IgM, including where it is found.
    A: Major Ig on B cells. Membrane bound as monomer, acts as primary antigen receptor. Secreted as pentamer and functions as blood group antibodies (ABO), Opsonins, complement activation, early polysaccharide antibody, and rheumatoid factor is usually IgM against IgG.
  13. Q: What are some overall functions IgG provides?
    A: Complement activation (G3>G1>G2; not G4). Opsonins for bacteria. Anti-viral neutralizing activity. Neutralizes diphtheria, and tetanus toxin.
  14. Q: What are the relative amount of each antibody?
    A: IgM = 10%. IgG = 75%. IgA= 15%. IgD=0.2%. IgE=not mentions, must be very few unless allergic reaction.
  15. Q: What are general properties of IgA?
    A: Coats resp. and GI tract. Anti-viral, polio, RSV, rubella, etc. Prevents antigen absorption and allergies (immune exclusion) ( his example was it preventing absorption of ragweed and thus not making IgE).
  16. Q: What are general properties of IgE?
    A: Allergens crosslink IgE and trigger release of histamine, leukotrienes, cytokines, and mediators of allergy. Immunity against parasites (directs eosinophils, monocytes, NK cells to parasites (if kids get a lot of parasites, they have fewer allergies because the IgE is busy).
  17. Q: What are general functions of IgD?
    A: NONE. It is an antigen receptor (on 50% of B cells) but it's not secreted and function in serum is unknown.
  18. Q: Which antibodies have subclasses and what are the subclasses?
    A: IgG has 4 subclasses and A has 2. G1, G2, G3, G4. A1 and A2.
  19. Q: What are the jobs of the 4 IgG subclasses?
    A: G1= antiprotein to toxins (eg. Diphtheria, tetanus, H. flu vaccine) G2= mainly antipolysaccharide. Pneumovax for S. pneumonia, and meningitis (infants don't make this) G3= short half life, viral antibodies, flu, and MMR. G4=unknown
  20. Q: What various proteins and receptors are found on a B cell?
    A: Ig monomers of all classes, receptors for Fc portions of antibodies, receptors for C3b (called CR2) activation by complement, CD19 is signal transducer for complement activation, MHC class II proteins.
  21. Q: What cell is the primary antibody producer?
    A: Plasma cells.
  22. Q: What are the four ways to measure immunoglobulin?
    A: (1) serum protein electrophoresis (2) Immunoelectrophoresis and immunofixation electrophoresis (3) radial immunodiffusion (4) nephelometry
  23. Q: When measuring immunoglobulins, what are we measuring in general terms?
    A: Most methods just give us a comparison between the various Ig groups so we can detect an increase in one group and recognize any gammopathies. Nephelometry is the only one good for quantification.
  24. Q: What are conditions associated with polyclonal hypergammaglobulinemia?
    A: Chronic infections, Chronic inflammation (lupus, RA, collagen vascular diseases etc), liver disease (alters metabolism of Ig).