7 - Antibodies in Immunity Flashcards
What is acquired immunological tolerance?
Continuous presence of non-self antigen before the immune system is fully developed leads to a permanent unresponsiveness to the non self antigen (induced antigen specific immunological unresponsiveness)
What is the reticuloendothelial system
Part of the immune system that consists of phagocytic cells in connective tissue
Are all secondary lymphoid organs independent
no. They are all connected by BVs and lymphatics. If you get a response at one then the effectors and the memory is distributed throughout the lymphatic tissue
What do BVs and lymphatics bring in and out
Bring in CELLS (WBCs) and antigen and take out effectors/antibodies/lymphocytes
How do APCs present epitopes
Major Histocompatability Complexes (MHC proteins)
What does node swelling usually indicate?
An immune response
What does the response of the IS to a foreign substance depend on?
Route and nature of the foreign substance i.e. non-infectious and infectious material are NOT treated the same
What does foreign material usually first encounter
Phagocytic cells of the reticuloendothelial system
What occurs in the secondary lymphoid organs
the APCs (specialised localised phagocytes) present antigen via the major histocompatability complexes (MHC molecules) to lymphocytes with specific compatible/high specificity receptors
What can the lymphocytes be classified into based on function
Effectors and regulators
Effectors
- antigen-dependent cell mediated cytotoxicity (K cells)
- antigen specific cytotoxicity ( CD8 T cells)
- B cells (antibodies)
- NK cells
Regulators
- Th cells
- regulator t cells
- CD4 T cells (cytokines)
What are the 3 types of shape recognition
- Common characteristic to many substances (non-specific immunity bacterial cell wall sugar)
- Unique characteristic of a particular foreign substance (specific immunity i.e. viral capsid protein)
- Common but in an uncommon context i.e. myocardium shapes on a streptococcal bacteria)
Innocuos Antigen
Shapes on things that are not harmful to us. In allergy/hypersensitive response the IS overreacts to the innocuous shapes we shouldn’t be responding to. Occurs especially when we breather it in or ingest it (epithelial surfaces) i.e. dust or pollen
What cells recognise a change in our cells i.w. tumour cells, virus infected or cancer cells
natural killer cells
What lymphocytes produce cytokines
CD4 T cells
CD8 cells?
Antigen specific cytotoxic cells
Do all lymphocytes have receptors?
Yes and all are antigen specific
What triggers differentiation of the pluripotent haemopoetic stem cells
hormonal influences usually to b driven along particular pathways when we need specific cells
What is the receptor on a B cell called
Like an antibody shape anchored into the membrane - surface immunoglobulin (sIg)
What is the receptor on a T cell
T cell receptor TCR
What are associated with the receptors on lymphocytes
Pointing out and recognising outside world - when bind need to send signal into cell. Receptors have signal transduction transmembrane molecules associated with them
Transmembrane molecule on B and T cells?
T cells - CD3 signal transduction molecule
B cells - CD79 signal transduction molecule
What is CD3 present on
ALL T cells (important in blood count)
How does lymphocyte response work
Antigen specific binding leads to changes in receptors that is transmitted into the cell creating a signal leading to a change in cellular activity i.e. diferentiation into antibody forming cells, helper or cytotoxic cells, or division
What does # of CD3 molecules tell you
number of t cells (both CD4 and CD8 have CD3)
What do B and T cells respond to
B cell can be free antigen or presented antigen
T cell HAS to be presenTed antigen
What are antibodies
Glycoprotein molecules
Made of 4 polypeptide chains
2 are identical and short (light chains)
2 are identical and bigger (heavy chains)
Forms globular protein held together by disulphide bonds
antibody structure
In the light chains 1/2 aa’s are identical in antibodies i.e. Constant
Other half is highly variable AAs i.e. variable region
In heavy chains, 3/4 is constant 1/4 (constant region of heavy chain/domains) is variable
What is in the middle of the heavy chain?
Hinge region
Region of AAs that allow arms of anibody to be flexible
What makes up the antigen binding site
The variable regions of both the heavy and light chains
There are regions of hypervariablity in these (fingers that can grab antigenic epitope)
What is special about the CH2 domain of the heavy chain
CH2 binds complement proteins (complement binding region) when antibody has a particular shape
What is special about the CH3 doman
From hinge region down is the Fc region (can crystallise)
But ALSO is recognised strongly by receptors on neutrophils and enhances phagocytosis
What percent of blood proteins do antibodies/Igs make up
1%
What are the 4 pp chains held together by
Disulphide bonds and non-covalent interactions
When can complement proteins bind to CH2 of the heavy chain
Only when the antibody s bound to antigen
Example of a primary response
Vaccination
