Antigens. Flashcards
Can antigens be part of PAMPs?
Yes, many PAMPs contain more that one antigen.
Will antigens always be part of a PAMP?
No, they can be molecules such as pollen or molecules from other animals.
What are 3 common antigens?
Antigens from PAMPs.
Self antigens.
Antigens on foreign molecules.
What are 4 things antigens can interact with?
B cells.
T cells.
Antibodies.
MHC molecules.
What part of a B cell or T cell will an antigen interact with?
A B or T cell receptor.
What region of an antibody will an antigen bind to?
The FAB region.
What happens when an MHC molecule binds to an antigen?
They can present the antigens to other immune cells.
Can T cells bind to any antigen?
No, they can only bind to an antigen after that particular antigen has been presented to them by an APC.
What part of an antigen presenting cell will antigens bind to?
The MHC complex.
What presents a new antigen to a T cell?
An MHC complex.
An APC.
What happens when an antigen is presented to a T cell by an MHC?
It promotes an immune response from the T cell.
What is the only way that a T cell can respond to an antigen?
If it gets presented that antigen by an MHC complex or an APC.
What part of a B cell recognises antigens?
Specialised receptors that are basically membrane bound antibodies.
Can B cells bind to free antigens without any stimulation?
Yes.
Do B cells need antigens to be presented to them before they can mount an immune response?
No, they can directly interact with antigens.
What are B cells known as once they have bound to an antigen?
As effector B cells or plasma cells.
What is the function of B cells that are bound to antigen?
They produce specific antibodies that bind to more antigens.
What is a humoral acquired immune response?
When B cells bind to antigens and secrete antibodies.
When will T cells become effector T cells?
When they bind to an antigen.
What 2 cells can be formed by effector T cells?
Cytotoxic T cells.
Helper T cells.
How does a capsule protect bacteria?
It allows them to hide their antigens from the immune system.
What are the 2 major properties that antigens have?
Immunogenicity.
Antigenicity.
What are the properties of an antigen with good immunogenicity?
It can induce a strong immune response.
What are the properties of an antigen with poor immunogenicity?
It cannot induce a strong immune response.
What are the properties of an antigen with good antigenicity?
It is able to bind strongly to components of the immune system.
What are the properties of an antigen with poor antigenicity?
It will not bind strongly to components of the immune system.
What are the 2 properties of a good immunogen?
They must be large.
The must have complex repeating units and complex molecules on their exterior.
How large must immunogens be in order to create an immune response?
At least 100 daltons.
Are proteins and glycoproteins good immunogens?
Yes.
Are lipids and nucleic acids good immunogens?
No.
What is the only nucleic acid that is a good immunogen?
CpG motifs (bacterial DNA).
What is the only lipid that is a good immunogen?
Bacterial LPS.
What are CPG motifs?
Bacterial DNA.
Why must good immunogens be relatively stable?
As they must remain in the body long enough to be picked up by the immune system.
Are inert molecules good immunogens?
No, as they cannot provoke an immune response.
How does the foreignness of an antigen dictate how good an antigen it is?
The more foreign an immunogen, the better it will be.
What molecules are said to make the best antigens?
Foreign proteins.
Will all immunogens be antigens?
Yes, but not all antigens are immunogenic.
This means some foreign molecules can bind to immune cells and not produce an immune response.
