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13 Cards in this Set
- Front
- Back
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1. What is an immunogen?
What is an antigen? What are three phases of specific immune response? |
a substance which elicits a specific immune response
Substances bound by antibodies **not all antigens are immunogens 1. Cognitive/recognition phase 2. Activation phase 3. Effector phase |
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2. What does the first phase of immune response involve?
What do T-cell receptors TCR consist of? |
Specific recognition of immunogen/antigen by receptors on B and or T-lymphocytes
**B cell receptors have antibody molecules Molecules structurally related to antibodies |
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3. What is an antigen?
What characteristics of a molecule contribute to immunogenicity? (six things) |
Substance that elicits a specific immunological response or reacts with antibody in vitro
1. Foreignness 2. Number of antigenic determinants/epitopes 3. Susceptibility to degradation 4. Size 5. T-independent antigens 6. Hapten |
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4. How does foreignness contribute to immunogenicity?
How does number of antigenic determinants and epitopes contribute to immunogenicity? How does susceptibility to degradation contribute to immunogenicity? |
Antibodies are not usually made of self molecules in their native configuration
Molecules with large numbers of different antigenic determinants make better immunogens than more uniform molecules Substances resistant to enzymatic degradation make poor antigens |
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5. How does size of a molecule contribute to immunogenicity?
How are T-independent antigens? What is Hapten? |
Smaller the molecules, the more complex its structure must be if it's to be immunogenic
Some can trigger a limited immune response w/o activation of T-cells Small molecule unable to induce an immune response by itself but can induce such a response when conjugated to a large carrier protein |
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6. Why are self molecules not usually immunogenic?
Three reasons... |
1. Foreignness is characteristic of immunogen/antigens.
2. Immature lymphocytes that recognize self molecules undergo apoptosis as a result of this interaction 3. Immune responses can be mounted to sequestered self-antigens which do not participate n this process |
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7. What is an epitope?
How does the number of epitopes affect immunogenicity? |
Structural part of an antigen that determines specificity of an antigen-antibody reaction
**Antigenic determinant Molecules with large numbers of different antigenic determinants make better immunogens than more uniform molecules |
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8. What type of epitopes do B-cells recognize?
What type of epitopes do T-cells recognize? |
Epitopes may be linear (continuous), or conformational (discontinuous)
Always linear, range 8-20 AA in length |
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9. What are conformational epitopes
How many AA do linear epitopes have |
Hydrophilic, on exterior surface of molecule, 20+ amino acids
6 amino acids |
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10. What is a hapten
What must be done before an immune response is elicited against it? |
Small molecule unable to induce an immune response by itself but can induce such as response when conjugated to a larger carrier protein
Antibodies made to epitopes which include hapten may react w/ unconjugated hapten **Haptens are antigens but not immunogens |
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11. Why is susceptibility to enzymatic degradation important for antigens?
What are most antigens dependent on? For a T cell to recognize an antigen what must happen? |
Substances resistant to enzymatic degradation usually make poor antigens
T cell dependent **must be recognized by both B and T cells for optimum immune response Must first degrade and present to the T-lymphocyte on the surface of an antigen presenting cell (APC) |
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12. How do T-dependent and T- independent antigens differ?
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T- independent antigens -immunogens can trigger a limited immune response without activating T-Cells
T-dependent antigens -antigen must first be degraded and presented to T-lymphocyte on APC surface -immune response then takes place |
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13. How are T-independent antigens?
How are the receptors on the surface of B-cells? |
Immunogens are less complex with repeating epitopes
Cross link antigen receptors on the surface of B cells |
