16 Questions
Which term refers to a molecule of low molecular weight that cannot induce an immune response by itself?
Hapten
What is the definition of an immunogen?
An agent that induces an immune response when introduced to the host body
What is the relationship between immunogens and antigens?
All antigens are immunogens but not all immunogens are antigens
What are antigen determinants or epitopes?
Small sites of simple chemical structures on the antigen surface to which antibodies or T-lymphocytes can bind
Which type of molecules become immunogenic when coupled with carrier macromolecules?
Haptens
What effect is associated with changes in antigen determinants?
Decrease in the specificity of antigen molecules
What is the term for the number of epitopes on an antigen molecule that bind to antibodies?
Antigen valency
Which phenomenon occurs when unrelated antigens share one or more identical epitopes, leading to the production of cross-reacting antibodies?
Cross reactivity
Which factor influences immunogenicity by providing cross-protective immunity to related pathogen strains?
Foreignness
Which chemical structure is considered non-immunogenic unless conjugated with protein to form lipoprotein or nucleoprotein?
Pure lipids
At what molecular weight are substances considered potent immunogens?
Above 100,000 Dalton
What is the term for a substance that, when mixed with antigen before its administration, induces the production of a stronger immune response against the antigenic substance?
Adjuvant
Which route of administration generally induces a better immune response for immunogens?
Subcutaneous or intramuscular injection
What factor influences immunogenicity by varying the ability to respond to a particular antigen according to the genetic makeup of animals?
Genetic constitution of the animal
Which type of molecules become immunogenic when coupled with carrier macromolecules?
Polysaccharides
What is the term for the ability of a substance to be immunogenic only when administered in an optimum dose?
Dose-dependent immunogenicity
Study Notes
Immunology Basics
- A hapten is a molecule of low molecular weight that cannot induce an immune response by itself.
- An immunogen is a substance that can induce an immune response, and an antigen is a substance that can bind to an antibody.
- Immunogens are also antigens, but not all antigens are immunogens.
- Antigen determinants or epitopes are the specific regions on an antigen molecule that bind to antibodies.
Immunogenicity
- Haptens become immunogenic when coupled with carrier macromolecules.
- Changes in antigen determinants can lead to a loss of immunogenicity.
- The valency of an antigen refers to the number of epitopes on an antigen molecule that bind to antibodies.
- Cross-reactivity occurs when unrelated antigens share one or more identical epitopes, leading to the production of cross-reacting antibodies.
Factors Influencing Immunogenicity
- Genetic makeup influences immunogenicity by varying the ability to respond to a particular antigen according to the genetic makeup of animals.
- Lipoproteins and nucleoproteins are considered non-immunogenic unless conjugated with protein.
- Molecular weight is a factor in immunogenicity, with substances above a certain molecular weight (typically >5,000) considered potent immunogens.
Immunogenicity Enhancement
- Adjuvants are substances that, when mixed with antigen before its administration, induce the production of a stronger immune response against the antigenic substance.
- The route of administration can influence immunogenicity, with some routes (e.g., intradermal) inducing a better immune response than others.
- Dose is a factor in immunogenicity, with the optimum dose required for a substance to be immunogenic.
Test your knowledge about immunogens and antigens with this quiz based on the lecture contents from the Faculty of Veterinary Medicine, Alexandria University. Explore the concepts of antigens, immunogens, and their specific interactions with the immune response.
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