Immunigens, Antigens, And Antibodies Flashcards
What are immunogens?
Any substance that can trigger an immune response in the body
All immunogens are antigens
What are antigens?
Any substance that is specifically recognized by the immune system
Not all antigens are immunogens
What are the 5 requirements for immunogenicity?
- Foreignness
- Size (>6kD)
- Chemical complexity
- Degradability
- Dosage
What are epitopes?
Regions on an antigen that are recognized by the immune system —> immune response
Are all antigens immunogens?
No, all immunogens are antigens, but not all antigens are immunogens.
What is the specific binding property of antigens?
Antigens bind specifically to antibodies or T cells.
What is a requirement for immunogenicity related to foreignness?
Immunogens must be foreign; the more foreign, the more immunogenic.
What molecular weight is generally immunogenic?
Molecules greater than 6kD are generally immunogenic.
Are homopolymers of amino acids immunogenic?
No, they are not immunogenic due to low chemical complexity.
What is necessary for antigen presentation?
If a substance can’t be broken down, it can’t be presented
- Susceptible to enzymatic degradation
- Stable for antigen presentation
What can insufficient antigen dosages cause?
Insufficient doses may lead to tolerance.
What is a hapten?
A low molecular weight molecule that is non-immunogenic by itself but can be immunogenic when conjugated with a carrier.
What type of molecule is rarely immunogenic?
Lipids are rarely immunogenic.
Which class of molecules is highly immunogenic?
Proteins and glycoproteins are highly immunogenic.
What is cross-reactivity in immunology?
The ability of an antibody to react with a second, closely related antigen.
What is the role of adjuvants in immunogenicity?
Adjuvants enhance immunogenicity by prolonging antigen persistence, causing inflammation, or improving immune cell processing.
Why are antibodies important? (5)
- Neutralize toxins/viruses
- Immobilize bacteria/parasites
- Activate complement
- Start opsonization
- Antibody-dependent cell mediated cytotoxicity (ADCC)
Where are hypervariable regions located in antibodies?
Hypervariable regions are located in both the light and heavy chains of antibodies.
What are the five major classes of antibodies?
IgG, IgA, IgM, IgE, and IgD.
What is unique about IgG antibodies? (3)
IgG can cross the placenta, activate complement, and mediate ADCC.
What is the primary function of IgA?
IgA provides defense on mucosal surfaces and is abundant in secretions.
Antiviral and antibacterial
What does IgE mediate?
IgE mediates Type I hypersensitivity reactions and is elevated during parasitic infections.
What is the first immunoglobulin produced after infection?
IgM is the first immunoglobulin produced and is efficient at complement fixation.
What adjuvant is approved for human use?
Aluminum hydroxide or phosphate
