The Adaptive Immune Response Flashcards
(21 cards)
What are humoral defences ?
Immune responses that occur in body fluids.
The defences are mediated by molecules rather than cells.
What are key features of humoral defences ?
They target Extracellular pathogens.
The effector molecules are antibodies, which are made by B-lymphocytes.
Where do B-cells come from ?
They are produced and mature in the bone marrow
What do B cells do ?
They have receptors on their surface which recognise and bind to specific antigens. They divide and produce many clones. They then release antibodies to mark the pathogen for destruction.
They can also differentiate in B memory cells.
What are the functions of antibodies?
- Neutralisation
- Opsonisation
- Agglutination phagocytosis
- Innate immune cell recruitment
- Activation of complement system
- T-lymphocyte recruitment
What is neutralisation ?
When antibodies bind to pathogens and block their ability to infect cells
What is opsonisation?
Antibodies coat pathogens making it easier for phagocytes to recognise and engulf
What is agglutination?
Antibodies bind multiple antigens at once causing them to clump together
What are antigens ?
Molecules that the immune system can recognise as foreign to trigger an immune response
What is found on the surface of all nucleated cells ?
MHC class 1 proteins
What do MHC class 1 do ?
They present endogenous peptides from inside the cell to cytotoxic T cells. If the cell is infected the peptides may be abnormal, triggering an immune response where T cells destroy it.
What are dendritic cells ?
A type of professional antigen-presenting cell that helps link the innate and adaptive immune system
What cells have MHC class 2 on their surface ? What type of cells are those ?
Macrophages, B cells and dentritic cells
They are all professional antigen-presenting cells.
What do APCs do ?
Present short peptide sequences of the pathogens that they have phagocytosed.
This is so T lymphocytes can recognise it and act against it.
What are the 2 classes of T-lymphocyte ?
- CD4+ helper cells
- CD8+ cytotoxic cells
Where are T-lymphocytes made? Where do they mature ?
Made in bone marrow
Mature in the thymus
What do CD4+ helper cells do ?
- They are activated once they recognise an antigen on MHC class 2.
- They then produce T memory cells and finish activation of B-lymphocytes.
- They release cytokines which can then activate CD8 cells.
What do CD8 cytotoxic cells do ?
- They scan the body for cells presenting foreign peptides on MHC class 1
- They then make pores in the membrane using perforin and granzymes
- This causes apoptosis so the cell and pathogen inside dies
What are regulatory T cells ? What do they do ?
A subset of CD4+ cells.
They release inhibiting cytokines which tells the body to stop attacking its own tissues by suppressing T cells, B cells etc.
How does HIV work ?
It invades CD4 cells which prevents they functioning so causes AIDS due to a weak immune system
What can dysfunction of T regulatory cells cause ?
Autoimmune diseases
