Lecture 12 (6B) - Immunological Memory Flashcards
Immunological memory
the ability of the immune system to respond quicker and better to pathogens that have been encountered previously
Damage and infection stimulates
inflammation
Inflammation
damaged tissues make proinflammatory cytokines
• macrophages in
• TNFα, IL-1, IL-6, IL-8
• the wound bleeds to wash out foreign bodies
• resident macrophages and the injured tissues initiate an inflammatory response
Inflammation first drives
the innate immune response • clot forms to seal the wound • macrophages • NK cells • neutrophils • fluid enters the site • IgM
keep under control until adaptive
Dendritic cells initiate
adaptive immunity
• DC gets pieces of pathogens and
• have TLR/pathogen recognition receptors on surface so can respond /recognize pathogens
• acts as danger signal
• upregulates B7 and CD40 on DC -> signal T cells to proliferate
Immature DC –> Mature DC
- in the tissues is scanning, finds danger signals
- maturation on meeting a microbial challenge (danger signals)
- becomes a mature dendritic cell that goes to the lymphatics and lymph nodes
- upregulates B7 and CD40 - the signal for the T cells to proliferate
- when mature starts chopping up bits of proteins , upregulates MHC on surface, puts protein in MHC, turns on B7 and CD40, goes to lymph nodes (primed DC)
Dendritic cells go to the lymph nodes
activates naive T cells - passes protein to other DC, they interact with naive T cells - find one that recognizes the MHC+peptide
• in through afferent lymphatics
• activate/prime T cells that proliferate
• TH1 helper T cells and cytotoxic T cells leave through efferent to the site of infection =
Cell-mediated immunity
clones of T cells leave lymph node back to site of problem
- CD4 or CD8
- CD8 kill directly - with perforin and granzymes
- Th1 cells support cytotoxic T cells and macrophages = cell mediated response, good for getting rid of pathogens that infect cells
- Th2 cells
Humoral immunity
Th2 cells help B cells make antibodies which are good at catching big pathogens
B cells become plasma cells
which produce huge amounts of diverse antibodies • IgM - makes this first, low affinitiy • IgG - blood • IgE - mast cells, allergies • IgA - mucosal
make a lot of IgG to send to site of infection
A fraction of the activated T and B cells become
memory cells and provide long-lasting immunity to that infection
A fraction of the activated T and B cells become memory cells and
provide long-lasting immunity to that infection
• cytotoxic T cells
• helper T cells
• B cells
- in an active immune response, there’s lots
- lots are left after an immune response, but not enough storage, so just want to keep the useful ones
After an active immune response
effector cells are stored for rapid deployment if infection re-occurs
• memory cytotoxic T cells
• memory helper T cells
• memory B cells
- still have more than the original, faster
- pathogens would also have to proliferate to keep up, but can’t –> can’t beat memory
Immunological memory can be maintained WITHOUT
continued exposure to the pathogen
• it is maintained by long-lived antigen-specific lymphocyte that persist for many years
Immunological memory is maintained by
long-lived antigen-specific lymphocytes that persist for many years
• can be maintained without continued exposure to the pathogen