Foundations in Immunology 3 Flashcards
What are properties of the adaptive immune system that is different to the innate immune system?
Very specific
Immunological memory
What antigen do B cells use to recognise free antigens?
BCR (surface IgM)
What receptor do T cells use when they are being shown an antigen?
MHC
How do antibodies from a memory cell bind to antigens compared to regular cells?
With much higher affinity
What is a naive B cell?
B cell that has not been exposed to an antigen
What happens once a naive B cell is exposed to an antigen?
Becomes a memory B cell or a plasma cell
What are the 2 kinds of adaptive immunity?
Active
Passive
What is active immunity?
Uses the hosts own immune cells
What is passive immunity?
Transfer of someone else’s immune cells
Which of active and passive immunity creates immunological memory?
Active immunity
What can active and passive immunity be further classified into?
Natural
Artificial
Where are B cells produced?
Bone marrow
What do B cells do on activation?
Differentiate into plasma cells
What are plasma cells?
Responsible for antibody production
Is it more important for B or T cells to be tolerant?
T cells because B cells need the help of T cells to make antibodies
What happens to B cells that recognise self antigens?
Die in bone marrow by apoptosis
What are epitopes?
Part of the antigen that antibodies bind to
How can epitopes differ from each other, other than their structure and what they bind to?
Some induce larger immune responses than others
What is an antigen?
Any substance capable of triggering an immune response
What does the structure of an antibody consist of?
Variable region
Constant region
What are the different antibody classes?
IgG
IgA
IgM
IgD
IgE
What is IgG good for?
Good opsoniser
What is IgA good for?
Protects mucosal surfaces, resistant to stomach acid
What is IgM good for?
Fixing compliment and opsonisation
What is IgD good for?
No known function
What is IgE good for?
Defends against parasites, causing anaphylactic shock and allergies
What is the antibody structure held by?
Disulphide bonds
What are the two kinds of chains in the antibody structure?
Light chains
Heavy chains
What receptor is in the heavy chains?
Fc
What receptor is in the light chain?
Antigen binding region
What are the 2 kinds of light chains?
Lamda
Kappa
How many kinds of light chain are present in each antibody?
One, with both chains being identical
What are the 2 regions of the heavy chain?
Constant region
Variable region
What is the variable region?
Antigen binding site
What are the 2 ways of activating an antibody?
T cell dependant
T cell independant
What is used to activate antibodies without T cells?
Mitogen
What is a mitogen?
Antigen with a very large number of repeated epitopes
When do B cells produce antibodies?
When they are activated
What is the first antibody that B cells produce?
IgM
What does the class of the antibody depend on?
The constant region
When is the compliment system activated by antibodies?
When they are bound to an antigen
What are the 3 ways that antibodies eliminate pathogens by?
Neutralisation
Opsonisation
Compliment activation
What does neutralisation do?
Discourages of prevents pathogens from initiating an infection
What does opsonisation do?
Targets for phagocyte
What happens to neutralised and opsonised complexes?
Phagocytoses by macrophages
What is antibody dependant cytotoxicity (ADCC)?
The process of killing antibody coated target cells by leukocytes which have specific Fc receptors for these bound antibodies
What is humoral immunity?
Aspect of immunity by the macromolecules found in extracellular fluid such as secreted antibodies and compliment proteins
What is cell mediated immunity?
Immune response that does not involve antibodies, but the activation of phagocytes and antigen specific cytotoxic T cells with the release of various cytokines
What is the process of B cell activation and class switching?
1) Antigen is recognised by BCR
2) B cell expresses MHCII and antigen complex on its surface
3) Gets recognised bt TCR of TH2 cell
4) CD4 on B cell also binds to CD4L of TH2 cell
5) TH2 cell releases cytokines (IL2/4/5) which are recognised by ILR on B cell (interleukin receptor)
6) This determines the class switching of the B cell
7) B cell produces antibodies
What determines the class switching of the B cell?
The cytokines released by the helper T cell
What is the process of compliment mediated activation of B cell?
1) C3b is bound to a pathogen and degrades to C3d, C3df and iC3b
2) C3d reamins bound to pathogen and binds to a receptor on the surface of the B cell called CR2
3) Binding of CR2 and IgM greatly enhances the signals into the B cell so it is activated
What receptor binds to C3d on a B cell?
CR2
