L1 - Overview of Immune system Flashcards
ROLE OF THE IMMUNE SYSTEM
i) what is an antigen?
ii) which part of the immune system is germline encoded eg cant be changed? which part is antigen specific?
iii) how does the innate immune system recognise antigens?
i) antigen is anything the immune system responds to
ii) GL encoded = innate
antigen specific = adaptive
iii) innate recognises antigens (PAMPs) by PRRs
CELLS OF THE IMMUNE SYSTEM
i) where are the cells initially produced? which cells are they produced from?
ii) which three cells are from a lymphoid lineage?
iii) name four cells from a myeloid lineage?
i) initially produced in the bone marrow from pluripotent haematopoietic stem cells
ii) lymphoid > T cells, B cells, NK cells
iii) myleoid > neutrophil, eosinophil, mast cell, RBC
CELLS WITH A MYELOID LINEAGE
i) what is the main function of a neutrophil? what is the appearance of the nucleus and the cytoplasm?
ii) which two cells are implicated in parasitic infections and allergic responses?
iii) what is the basophil tissue resident counterpart?
iv) what are monocytes called in the tissue? what name two roles
v) what are dendritic cells specifically for?
i) phagocytosis
- multilobed nucleus and granular cytoplasm
ii) eosinophils and basophils
iii) basophil in tissue > mast cell
iv) monocytes in tissue = macrophages
- phagocytosis and antigen presentation
v) dendritic cells are just for antigen presentation
LYMPHOID LINEAGE
i) what cells are they a similar size to? are they mostly cytoplasm or nucleus?
ii) which cells make antibody and do antigen presentation?
iii) what are the two types of T cells? what does each do?
iv) what type of immunity are T and B cells involved in?
v) which immune system are NK cells part of? what do they do to infected cells?
i) lymphoid cells are a similar size to RBC
- little cytoplasm and big nucleus
ii) B cells make antibody and do APC
iii) T cells = Cd4 (help other components of immunity) and CD8 (kill infected cells)
iv) T and B cells = adaptive immunity
v) NK cells part of innate immunity
- direct lysis of infected cells
COMMUNICATION - CYTOKINES AND CHEMOKINES
i) what are cytokines? what are they important for?
ii) what is the main role of chemokines?
iii) what type of molecule are interleukins?
iv) name three cytokines
v) what forms the basis of seperating innate/adaptive immunity?
i) cytokines are small proteins released by cells that have an effect on another cell
- important in communication between immune/other cells
ii) chemokines main role is temporal and spatial organisation of cells and tissues
iv) interleukins are cytokines
iv) TGFb, IFN-g, TNFa
INNATE ANTIGEN RECEPTORS
i) do they recognise specific antigens?
ii) which receptors do they use? what do these receptors recongise on target cells?
iii) how do cells of innate imm sys not recognise host cells?
iv) how are they encoded? what does this mean?
iv) is there clonal distribution
i) do not recognise antigen specifically
ii) use PRRs that recognise PAMPs
iii) PAMPs are only seen in lower organisms
iv) PRRs are germline encoded and same on every cell
iv) not clonally distributed
MANNOSE BINDING LIGAND
i) what residues does it recognise? (2)
ii) what pattern does it specifically look for on cells?
iii) why does MBL not bind host cells?
i) recognises mannose and fucose residues
ii) residues need to be on the correct spacing
iii) MBL doesnt bind host cells as the residues are in a different spacing
ADAPTIVE ANTIGEN RECEPTORS
i) do they recognise antigen specifically?
ii) name two adaptive receptors
iii) how are they produced? what does this therefore lead to?
iv) are they clonally distributed? what does this mean?
v) what two things do they permit?
i) yes
ii) B and T cell receptors
iii) produced through random somatic recombination between gene segments
- leads to huge receptor diversity
iv) yes they are clonally distributed - originally there is one copy of each receptor but as the cell divides it produces clones
v) permit specificity (ability to recog specific antigens) and memory (learning through clonal expansion - cells with receptors to antigens that have been previously encountered)
B CELLS
i) which two forms can the B cell receptor (antibody) be in?
ii) what does the B cell receptor recognise?
iii) label A, B, C
i) surface bound or secreted
ii) B cell R recognises intact antigen
iii) A - variable region
B - constant region
C - light chain
T CELL RECEPTOR
i) is the receptor attached to the surface or secreted?
ii) what does it recognise?
iii) what two chains does it comprise of?
i) cell surface receptor
ii) recognises processed antigen in the form of linear peptides
iii) alpha and beta chain
GENERATION OF ADAPTIVE IMMUNE RECEPTORS
i) how are T and B cell receptors produced? which three gene segments does this involve? what does this result in?
ii) when are the most useful receptors selected?
iii) which two genes is the light chain made of? which three genes is the heavy chain made of?
iv) what is a disadvanatage of making receptors in this way?
i) produced by random recombination events
- between V, D, J gene segments (all spliced together)
- results in huge receptor diversity
ii) most useful receptors selected after birth on exposure to pathogens
iii) light chain = V+J
heavy chain = V+J=D
iv) disadantage = lots of receptors are junk
T AND B CELL MEMORY
i) on first exposure to an antigen - how long does it take to get a primary response?
ii) does the antibody level ever drop to baseline after primary exposure?
iii) what happens if the body meets antigen A again?
iv) what happens to most clonally expanded T and B cells after primary infection? what happens to a few of them?
i) takes a few days to get a primary response
ii) never drops to baseline
iii) meet antigen A again > bigger and faster response
iv) most clonally expanded T/B cells die off but a few remain as long lived memory cells
CD8/CD4 T CELLS
i) what happens when a virus infects a cell?
ii) which MHC does CD8 T cell receptor recognise?
iii) what are the only cell types that CD4 T cells respond to? give two examples
iv) which MHC is peptide presented on when recognised by CD4 cell? what needs to happen for CD4 to recog this?
i) virus infects cell > viral prots synthesised in cytosol > ER > viral fragments presented on MHC I
ii) CD8 recognises viral presentation on MHCI
iii) CD4 T cells only respond to antigen on APCs eg dendritic cells or B cells
iv) presentation of peptide on MHCII
- CD4 needs the specific receptor for that antigen to recognise it
ACUTE INFLAMMATION
i) name four cardinal features
ii) name three blood vessel processes that underlie the process?
iii) what are clinical feaures defined by?
i) hot, painful, red, swollen
ii) vasodilation, adhesion molecules, increased permeability
iii) clin features defined by an interaction between pathogen and host immunity
