Immunology- Adaptive Response Flashcards
Which cells are involved in adaptive response?
B cells and T cells
How do B cells and T cells recognise antigens on a pathogen?
They can recognise antigens because of the receptores present on the plasma membrane of these cells. These receptors are specialised proteins.
What are the two types of T cells?
CD4 T cells, also known as helper T cells.
CD8 T cells, also known as killer cells.
Where can T and B cells be found?
B cells start of in the bone marrow and T cells in the thymus. There are 10 to power 12 different B cell receptors, similarly there are 10 to power 8 different T cell receptors. Adaptive immune cells can be found in the spleen, lymphoid organs, blood.
Do B cells need help from other cells to recognise antigens?
No, B cells can recognise any antigen with their B cell receptor without any help.
Do T cells need any help from other cells in recognising antigens?
Yes, T cells need accessory cells to tell them there is a pathogen present in the body. They cannot distinguish.
How do T cells find out there is a pathogen in the body?
Through MCH molecules. These molecules are present in accessory cells, which are B cells, macrophages or dendritic cells. These cells turn antigens into short peptide sequences, by breaking them up using enzymes. These peptide sequences get stuck onto other molecules, which are the MCH molecules.
What are the two types of MCH molecules?
MCH class l
MCH class ll
Which type of T cells recognise which type of MCH?
CD4 T cells recognise MCH class ll.
CD8 T cells recognise MCH l.
How do B cells protect the host?
B cells can present antigens to T cells, turn into plasma cells and make antibodies that can prevent infection, activate complement and aid phagocytosis.
What are the 5 types of antibodies?
IgA
IgE
IgD
IgG
IgM
How do antibodies protect the host?
- Neutralising antibodies- these neutralise the pathogen and stop it from infecting the host.
- Antibodies stimulate complement, which is a protein cascade that produces membrane attack complex which destroys pathogen.
- Antibodies use their bottom part and bind to the receptor on phagocytes, which allows phagocytes to take in the pathogen and destroy it with enzymes and toxic molecules like the respiratory burst.
How do CD4 T cells recognise antigens on MCH class ll?
CD4 T cells coordinate the immune response against pathogens and they do that by communicating with accessory cells which have the MCH class ll molecules. These molecules are mainly expressed by professional antigen presenting cells- b cells, macrophages and dendritic cells.
How do CD8 T cells recognise antigens on MCH class l?
CD8 T cells are known as killer cells, apart from mature red blood cells, every cell have MCH class l molecules, so when these cells are infected the MCH class l molecules communicate with killer cells to tell them they are infected. CD8 T cells than will kill these infected cells and remove them.
How do CD4 T cells help other immune cells?
CD4 T cells make dendritic cells better at stimulating CD8 T cells, which helps CD8 T cells make a stronger response.
If dendritic cells stimulate CD8 T cells in the absence of CD4 T cells, than there will be sometimes a response, but there won’t be immune memory against that pathogen.
CD4 T cells help B cells generate high affinity antibodies and generate different immunoglobulin.
CD4 T cells activate macrophages to kill phagocyted pathogens more effectively.
What do CD8 T cells do?
They kill infected cells at the site of infection and trigger apoptosis. They also kill tumour cells.
What does immunological memory enable?
It enables rapid control of pathogens net previously. Memory cells can act quickly upon re infection.
Memory B and T cells preform the same function as activated cells, but they remember the training they received during the first immune response, which means the 2nd time the response will be quick. This means stopping the growth of the pathogen and reducing the chance of the host getting unwell.
