Immunology Flashcards
What is the difference between interferon and interferon gamma?
Interferon (type I) is secreted by virus-infected cells to signal nearby cells to beware/protect their machinery.
Interferon gamma (type II) is secreted by NK cells and activated helper T cells to signal cytotoxic T cells, NK cells and macrophages to proliferate and to secrete cytotoxic compounds
What is the one cell type that all APCs only ever present to?
Helper T cell
MHC I:
Who expresses it?
What is it displaying?
Who recognizes it (who is it displayed TO)?
MHC I is expressed by all nucleated body cells (i.e., not RBCs)
MHC I is displaying bits and pieces from inside the cell (may include virus or cancer)
MHC I is recognized by CD8 on cytotoxic T cells
MHC II:
Who expresses it?
What is it displaying?
Who recognizes it (who is it displayed TO)?
MHC II is expressed by APCs (antigen-presenting cells - macrophages, dendritic cells, B cells)
MHC II is displaying bits and pieces from things that the cell has phagocytosed (i.e. things from extracellular environment of body - may include bacteria, parasite, etc)
MHC II is recognized by CD4 on helper T cells
Which lymphocyte type is necessary in order to activate the adaptive response?
Helper T cell
Which type of helper T cell activates B cells and which type activates cytotoxic T cells?
B cells are activated by TH2
Cytotoxic T cells are activated by TH1
What class of antibody do B cells have on their surfaces as receptors?
IgM
according to Dr. Cameron - book says they use whichever type of antibody they are going to eventually produce
Name 4 cell types that have Fc receptors on their surface.
- B cells* (use IgM antibodies as antigen receptors - IgM is attached to B cell surface via Fc portion of antibody)
- Mast cells* (have IgE attached to their surfaces that gets sensitized)
- Macrophages* (to use antibodies as opsonins)
- NK cells* (to signal that the cells with antibody attached should be destroyed)
Which antibody class gets secreted to mucosa?
IgA dimer
Which antibody class binds to parasites?
IgE
Which antibody class forms a pentamer in blood?
IgM
Which antibody class crosses the placenta to provide passive immunity for fetus?
IgG
Which antibody class is found in breast milk and provides passive immunity for breastfed baby?
IgA
Which antibody class is the first to be secreted in a PRIMARY response to a given infection?
IgM
Which antibody class is the second to be secreted in a PRIMARY response to a given infection?
IgG
Which antibody class is the first to be secreted in the SECOND response to a given infection?
IgG
Which antibody class is secreted in HIGH AMOUNTS in the SECOND response to a given infection?
IgG
Type I hypersensitivity:
Onset timing?
Main cells/players?
Immediate/rapid onset (e.g. peanut allergy)
Sensitized mast cells with IgE on surface
Type II (cytotoxic) hypersensitivity:
Onset timing?
Main cells/players?
Reaction on initial contact (e.g. blood typing)
Antibodies reacting to antigen on cells -> complement
Type III (immune complex) hypersensitivity:
Onset timing?
Main cells/players?
Takes days to damage surrounding tissue e.g. kidney
IgM and IgG in blood become saturated with their antigen, precipitate, complement is activated
Type IV (delayed) hypersensitivity:
Onset timing?
Main cells/players?
A few days (e.g. TB skin test, contact dermatitis, rejection of grafts)
Activated helper T cells, macrophages
Who releases and who responds to IL-1 & TNF?
Macrophages release IL-1 and TNF as they dock with a helper T cell…gets the helper T cell going
Who releases and who responds to IL-2?
Helper T cells release IL-2 to activate nearby cells who are seeing their antigen (including themselves!) - could be cytotoxic T cells, could be B cells
How do cytotoxic T cells kill?
perforin, granzymes
