Antigens Flashcards
What does the innate immune system recognize?
PAMPS - pathogen associated molecular patterns
What does the adaptive immune system recognize?
Antigens
Define antigen
Any molecule that can interact specifically with the immunoglobulin (Ig) receptor of B-cells or the T-cell receptor complexed with MHC
Do all molecules induce immunity?
No
What is an immunogen?
A molecule that induces a specific immune response
Are all antigens immunogens?
No
Are all immunogens antigens?
Yes
Humoral Immunogens
(B cells)
Cell mediated Immunogens
T cells
Are proteins recognized directly?
No
How can we recognize proteins?
Peptides processed from the protein are seen in association w MHC molecules
What are the 4 properties of an immunogen?
- Foreignness
- Molecular size
- Chemical Heterogeneity
- Degradability
To serve as an immunogen, a molecule must be seen as “….”?
Non-self
What is the degree of immunogenicity dependent on?
The degree of foreignness
The greater phylogenic distance b/w species typically means what?
Greater the chance of immunogenicity
What are 2 exceptions to foreigness?
- Highly conserved molecules like collagen or cytochrom c may not be immunogenic even in distant species
- Some self molecules may sequester an immune response (sperm or lens tissue) in animal they came from
Is there a correlation b/w size and immunogenicity?
Yes, there is a sweet spot
What are the best immunogens in the range of?
100,000 Da
Small molecules - what size? are generally poor immunogens
5-10,000
Will size alone make a good immunogen?
No, the more complex the better
Are sythentic homopolymers immunogenic?
No, they are boring we want complex
How do we increase immunogenicity in terms of chemial heterogeneity?
Proteins w more complexity in primary structure and those showing secondary, tertiary, and quaternary structure
What do we have to do to proteins in roder for them to be presented by MHC to activate Tcells?
Degrade proteins
Why is an insoluble antigen better than a soluble?
Insoluble is more likely to be phagoctosed & processed
