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32 Cards in this Set

  • Front
  • Back
What is an immunogen?
any substance that can induce a cell-mediated or humoral immune response
What is an antigen?
a substance that is recognized by a particular surface Ig or TCR and is a target of an immune response

all Ags are immunogens but not all immunogens are Ags
What is a hapten? Give an example.
a small molecule which can elicit an immune response only when attached to a large carrier such as a protein

ex. urushiol, a toxin found in poison ivy
The best immunogens are what?
LARGE proteins

the most foreign to the host, the better the immunogen
What factors affect the response to immunogens?
1. Amount of immunogen - excessively large doses can lead to tolerance, too little will not elicit a response

2. Route of exposure

3. Genotype of recipient - the type of MHC, B-cell and T-cell genes will influence the degree of reactivity

4. Repetition - boosting leads to increase response

5. Administration with other immunogens or adjuvants can alter the immune response
What is an adjuvant?
substances that when mixed with and co-injected with Ag enhance the immunogenicity of that Ag
What is the only adjuvant approved for human use by the FDA?

causes time of exposure to Ag to increase from days to weeks

increases the size of Ag making it amenable to phagocytosis
What are the 5 immunoglobulin classes?
IgM, IgG, IgE, IgA, IgD
What is the major Ig in normal human serum?
What is the second Ab made in response to infection?
What immunoglobulin(s) can cross the placenta?
What is the first Ab made in response to an infection?
What immunoglobulin(s) contain a J chain?
IgM, IgA
Membrane bound and secreted IgM exist as what?
membrane bound - monomer

secreted - pentamer
When is IgA activated?
when the gut is exposed to Salmonella, cholera, gonorrhea, etc.
Where can secretory IgA be found?
breast milk, saliva, tears, mucus
Which immunoglobulin is more susceptible to proteolysis?
What is the function of IgD?
function is unknown
Where can IgE be found and where is it scarce?
found on surface of basophils and mast cells

scarce in serum
What is the function of IgE?
associated with allergies and may play a role in immunity to helminthic parasites
What is an assay for IgE activity?
Prausnitz and Kustner reaction (wheel and flare rxn)
What are the 3 classes of epitopes?
1. Isotypic
2. Allotypic
3. Idiotypic
Describe isotypic epitopes.
found in constant region

define each heavy chain class and subclass

within a species, each normal individual will express all isotypes in the serum
Describe allotypic epitopes.
subtle amino acid differences that occur in some but not all members of a species
Describe idiotypic epitopes.
generated by conformation of the amino acid sequences of the heavy and light chain variable regions

each Ab has multiple idiotypes the sum of which is called the idiotype of the Ab
Valency of an Ab refers to what?
the number of antigenic determinants that an individual Ab can bind (at least 2 and sometimes more)
What is included in the basic structure of Igs?
2 heavy and 2 light chains
disulfide bonds for stability
variable and constant regions
hinge region (flexible)
oligosaccharides on constant heavy region
What breaks Abs into 3 pieces: FAB, FAB, and Fc
What is the function of FAB?
these fragments contain the Ag binding sites of the Ab
What is the function of Fc?
the effector functions of Igs are mediated by this part of the molecule
Where is the Fc receptor located?
on all effector cells of the immune system: NK cells, macrophages, neutrophils, mast cells, B cells, etc.
What is the function of the Fc receptor?
binds to Abs that are attached to infected cells or invading pathogens thereby helping in the elimination and identification of microbial pathogens