L4 - Antigen Recognition Flashcards
What cells express TLR?
Sentinel cells such as macrophages and dendritic cells
What does TLR4 recognize and where is it found?
LPS, outer membrane surface
What does TLR5 recognize and where is it found?
Bacterial flagellin, outer membrane surface
What does TLR3 recognize and where is it found?
dsRNA, endosomal membrane
What does TLR7 recognize and where is it found?
ssRNA, endosomal membrane
What does TLR8 recognize and where is it found?
ssRNA, endosomal membrane
What does TLR9 recognize and where is it found?
CpG DNA, endosomal membrane
What TLRs are only found on endosomes?
TLR3, 7, 8 and 9
What happens after TLRs engage PAMPs?
Pathway via TIR receptor, recruitment of adaptor proteins (MyD88-dependent/TRIF dependent)
- Recruitment of adaptor proteins results in activation of transcription factors such as NF-kB or IRF
What happens after activation of NF-kB?
Increased expression of cytokines, adhesion molecules, costimulators
- Inflammation
What happens after activation of IRF
Increased expression of type 1 IFN
- Antiviral state
Are DAMPs recognized by PRRs?
Yes
What are the differences between antigen that immunoglobulin can recognize compared to T-cell receptors?
Immunoglobulins can recognize proteins, lipids, carbohydrates, nucleic acids, metabolites and sugars.
T-cells can only recognize peptide in complex with MHC
What is an immunogen?
A substance which induces a specific immune response
T/F: All antigens are immunogens
F. All immunogens are antigens but not all antigens are immunogens.
What is the difference between an epitope and an antigen?
Multiple epitopes can be found on the same antigen. Epitope refers to a contact site on an antigen
What is the relevance of the hapten-carrier complex?
The hapten is non-immunogenic itself, but can generate an Ab response when covalently linked to a carrier, usually protein or polypeptide
e.g. ovalbumin
What types of interactions occur between antigen and antibody?
Electrostatic, hydrogen-bonds, hydrophobic forces, Van der Waal forces (non covalent)
What is the difference between conformational determinants and linear determinants?
Conformational: 3D shape, lost by denaturation
Linear: Linear, determinant found in denatured protein or native if accessible in linear form
