Flashcards in Immunology 5 and 6 Deck (77)
What is an antigen?
An substance which can cause an adaptive immune response by activating B cells and T cells
Where are T cells and B cells found?
Constantly circulate through the blood, lymph and secondary lymphoid tissuesInactive until meet an antigen
What is the purpose of B cells?
Key role in defence against intracellular pathogens via production of antibodies
Purpose of T cells?
Key role in defence against intracellular pathogens (viruses, mycobacteria)
What are the 2 different types of T cells?
Helper T cellsCytotoxic T cells
What is the role of helper T cells?
Key regulators of the entire immune system
What is the role of cytotoxic T cells?
kill virally infected body cells
How do T cells recognise antigens?
Through their T cell antigen receptor
What is the T cel antigen in terms of proteins?What chains does it have?
Membrane-Bound protein heterodimer1 X Alpha chain1 X beta chain
How does B cells recognise antigens?
Through their b cell antigen receptor
What are B cell antigen receptors?What chains does this have?
Membrane bound antibody (IgM or IgD)2 X light chains2 X heavy chains
What is another name for antibodies?
What are antibodies?
proteins that are produced by B cells in response to an antigen and which bind specifically to that particular antigen
What are the 2 different forms of antibodies?
Those expressed on the surface of B cellsThose secreted as soluble proteins in extracellular fluids
What type of pathogens do antibodies provide defence against?
Extracellular pathogens (most bacteria, viruses and toxins)
What type of regions do both the heavy and light chains have on immunoglobulins?
Constant regionsVariable regions
Does the constant region or the variable region form the antigen binding site?
What are the 5 different types of antibodies that exist?What makes them different?
IgMIgGIgAIgEIgDDifferent heavy chain constant regions
Heavy chain constant region of IgM?
μ heavy chain
Heavy chain constant region of IgG?
γ heavy chain
Heavy chain constant region of IgA?
α heavy chain
Heavy chain constant region of IgE?
ε heavy chain
Heavy chain constant region of IgD?
δ heavy chain
What is the epitope?
the part of an antigen molecule to which an antibody attaches itself
What are antibody heavy and light chain proteins encoded for by?
Segmented genes in the germ-line genome of haematopoietic stem cells
What happens to gene segments as individual B cells develop?
They randomly rearrange (this also happens in TCR alpha and beta chains in developing T cells)
How is there more antibodies in the human body that there are entire genes in the human genome?
There is radom rearrangement of the segments of genes that code for antibody heavy and light chain proteins in individual developing B cells (a similar process also occurs in developing T cells)
What type of lymphoid tissues do adaptive immune responses occur in?
Secondary lymphoid tissues
What do mature antigen-specific T cells and B cells constantly re-circulate between?
Different primary lymphoid tissues, the blood and lymphatic vessels