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23 Cards in this Set
- Front
- Back
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1. Where are antibodies found?
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1. Highest concentration in serum
2. Lymph, saliva, CSF, mucous, tears, colostrums, seminal fluids |
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2. What is the chemical makeup of the immunoglobulin molecule?
What is the basic structure of the immunoglobulin molecule? How many basic units do Ig consist of? |
Class of molecules call immunoglobulins (Ig) which are chemically glycoproteins
Basic unit is 4 constituent polypeptide chains (2 heavy, 2 light) linked by disulfide bonds Consists of 1, 2, or 5 basic units |
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3. How many functional domains do each antibody have?
What are they? What is the Fab domain? What does the Fc portion determine? |
Two functional domains
1. Fab (fragment antigen binding) 2. Fc (fragment crystallized) Portion that binds antigenic determinant (epitope) Determines class of immunoglobulins |
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4. What does Fc portion determine?
Where is the variable region of the antigen binding site located? How are the variable regions linked? |
Characteristics unique to specific class
-fix complement -cross placenta Located in NH2 terminal portion of heavy and light chains Linked by joining regions to constant regions of chains |
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5. What does the variability of AA sequences in the Fab portion of the molecule make possible?
How are sequences in the the variable region? What do conserved regions constitute? |
Different antibody specificity
Some sequences are conserved and other hypervariable Constitute framework to correctly orient hypervariable regions to make contact w/ antigen |
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6. How many classes of immunoglobulins are there, name them?
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5 immunoglobulin classes
1. IgA (2 subtypes) 2. IgD 3. IgE 4. IgG (4 subtypes) 5. IgM |
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7. How do the various classes of immunoglobulins differ with respect to structure?
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Classes of immunoglobulin determined by heavy chain
1. IgA utilizes an (upside down A) heavy chain 2. IgD a * 3. IgE an , 4. IgG a ( 5. IgM a :. |
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8. How do the various classes of immunoglobulins differ with respect to biologic characteristics?
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2 classes light chain designated kappa and lambda
For a given antibody molecule there are 2 identical heavy chains utilized and 2 identical light chains (kappa or lambda) |
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9. What is an isotype?
What is an allotype? What is an idiotype? How are antibody molecules when introduced into an appropriate host? What is the degree of antigenicity related to? |
Antigenic determinants present in all members of a species
Antigenic determinants which vary between members of a species Antigenic determinants existing in the variable regions of the antibody molecule Immunogenic Related to the number of foreign epitopes |
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10. What are monoclonal antibodies?
How are they made? What is hybridoma technology? |
Antibodies made by a single clone of antibody producing cells
**all are identical and thus directed against the same epitope Can be made in the laboratory Antibody producing cells are fused with cancer cells resulting in hybrid cells with infinite capacity for replication **can be cloned as single cells and expanded resulting in cell cultures producing identical antibody molecules |
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11. What are polyclonal antibodies?
When are they produced? |
Directed against a number of different epitopes
During typical immune response by a variety of activated B-cells clones |
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12. What does heterogeneity result from?
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Presence of relatively small number of different Ig genes and genetic recombination that occur during the course of differentiation of a progenitor cell into a mature B-lymphocyte
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13. What is antigenic specificity determine by?
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Gene segments coding for the Fab portion of the antibody molecule
**variable portions of light and heavy chains |
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14. How many classes of light chains do humans have?
What does the light chain consist of? |
Two classes designated 6 and 8 each coded on a different chromosome
5' variable segment (V) followed by a joining segment (J) and ending in a constant segment (C) |
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15. How is the 6 chain arranged?
How is the 8 chain arranged? What determines antigen binding specificity? |
6 chain - ~100 different V segments, 5 J and a single C
8 chain- ~ 100 different V segments, 6 J, and 6 C Determined by V-J *have about 500 and 600 possible combinations for 6 and 8 |
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16. How do a relatively small number of genes provide for such enormous diversity of antigen specificity?
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1. Diversity segments
2. Heavy & light chain rearrangement 3. Junctional diversity from imprecise recombination 4. Heavy chain genes 5. B cells have high rates |
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17. What diversity is seen heavy chains?
What is responsible for antigen binding specificity? |
~200 V, >20 D segments, 6J, 9C segments
VDJ responsible for antigen binding specificity **24,000 combination |
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18. Where does junctional diversity from imprecise recombination occur?
What are heavy chain genes? |
Recombination can occur at any of several nucleotides at the ends of gene segments
Addition of up to 15 nucleotides to N-region of gene segments during V-D-J joining |
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19. What are at least 5 mechanisms that contribute to generation of antibody diversity?
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1. Multiple copies of V, D, and J
2. Junctional diversity 3. Insertion of N (non-templated) nucleotides (heavy chain) 4. Combinational diversity (heavy and light chain pairing) 5. Somatic mutation (an antigen driven process) |
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20. What is the mechanism for the generation of membrane bound versus secreted immunoglobulin?
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Membrane form
-C terminal sequences which compromise a transmembrane and cytoplasmic domain Differential RNA processing is responsible for the generation of the two forms |
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21. Where are membrane form IgM and IgD found?
What do activation and differentiation of B cells to plasma cells result in? |
On mature B-cells where they serve as antigen receptors
Switch to synthesis of secreted form of Ig |
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22. How are immunoglobulins initially synthesized?
Where do switch sites occur in antibody class switching? |
Synthesized by cells as IgM and IgD classes
Occur 5' to all C region gene segements except * |
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23. What is the mechanism of antibody class switching?
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1. IgM and IgD are both made in the same cell through differential RNA splicing
2. Recombination between switch segments (looping out) is responsible for expression of other Ig classes **mediated by cytokins **Class switching is an antigen driven process |
