Lec 4 - Adaptive - Cell Mediated Flashcards
What are thymus independent and thymus dependent antigens?
TI - antigens can stimulate a B cell response w/out the aid of T cells
TD - antigens require T cells to stimulate a B cell response
What B cell activities are aided by T cells?
B cell somatic hypermutation and class switching
Describe the 3 main functions of CD4+ve T helper cells
- helps B cell make antibodies
- aid in making cytotoxic T cells
- release of cytokines to stimulate macrophages, NK cells (leukocytes)
What is the main function of CD8+ve cytotoxic T cell?
kill virally infected host cells
Draw a Tcell receptor that recognises antigens. describe what it looks like and the exons that encode it
- looks like Fab arm of an Ab
- separate exons encode V & C regions, only 1 exon needed for C region whereas multiple exons for V region

How do T cells recognise an antigen (generally) and how does this differ to B cells?
B cells can recognise soluble, free antigens whereas T cells recognise antigens that are present of Major Histocompatibility proteins that have been processed
Describe what cells present and what cells recognise MHC I / II proteins
PRESENT
- MHC I - all nucleated cells
- MHC II - macropages , dendrites, B cells
RECOGNISE…
- MHC I - CD8+ve cytotoxic
- MHC II - CD4+ve T helper
- Draw a complex between a Cytotoxic T cell and a virally infected host cell
- State how the protein gets to be on MHC I on surface
- in the cytosol the pathogen components degraded (proteasome) and directed to ER where they interact w/ MHC I and are shuttled to surface and expressed

- Draw a complex between CD4 and macrophage
- State how the antigen gets to be on the surface w/ MHC II
- macrophage (eg) takes up the pathogenic material, endosome formation and protein interacts w/ MHC II in endosome, fuses to the surface

T CELL EFFECTOR FUNCTION
What are cytokines? Describe them and list 4 examples
cytokines are hormones of immune system, produced and act locally on cells with cytokine receptors (eg NK cells, macrophages)
- interleukins
- TNF
- interferons (virally infected host cells)
- chemokines (chemotaxis)
Draw a diagram that illustrates the function of TH1 cells

What are the 2 effects of TH1 cells and give an alternative name
INFLAMMATORY CD4 cells
- PRODUCTION of IL-2, TNFa, IFNy. cytokine release, activation of macrophages, promotes inflammation
- enables B cells to produce opsonising antibody IgG
What is the function of TH2 cells and how does it do this?
- allow response to helminths/allergens
- TH2 cell binding to B cells allows class switching to IgE antibody
- production of IL-4,6,10

Give an alternative name for TH2 cells
HELPER CD4 cells
What are TREGs?
- T regulatroy cd4 cells
- produce anti-inflammatory cytokines (eg IL-10)
- reduces inflammation by B cells
- overall leads to the suppression of the immune system after infection dealt w/
Describe the mode of action of CD8+ve cytotoxic T cells
- Bind to virally infected host cells via MHC I
- secrete perforin to allow protease to be secreted in and cause caspase cascade to induce apoptosis
- can also secrete IFN/TNF for recruitment of macrophages
How do CD8 cells differ from NK cells?
CD8 cells can kill 100s infected cells and can only recognise specfici cells presenting MHCI