Immunology Flashcards
Two types of immune systems
1) Innate
2) Adaptive
Antigen
foreign molecule that can initiate an immune response
What does the innate immune system do?
- Prevents entry to body through physical and chemical barriers
- Detects entry of pathogens
- Eliminates pathogens (inflammation)
How does the immune system trigger an inflammatory response?
- Macrophages release chemokines to recruit immune system cells to the site of the cut
- Histamine dilate blood vessels, which makes them more permeable
- Neutrophils are recruited to remove pathogens by phagocytosis
Toll-like receptors
part of the innate immune system
bind to molecules that are found in pathogens that are not found in the self
Activates different! downstream pathways to combat infection
General Characteristics of the innate immune system
- Generic: can distinguish between bacteria vs. fungi, but not specific different strains of bacteria
- Rapid
- Ready at all times
General characteristics of the adaptive immune system
- Specific
- Slow response
- Must be activated
Two types of lymphocytes
B-cells
T-cells
B-cell vs. T-cell recognition
B-cell can bind directly to an epitope on an antigen
T-cells need the antigen to be presented to them
Epitope
small region that a B-cell/T-cell can bind to on an antigen
How are specific epitopes recognized?
there are variable regions in the antigen binding sites of B-cells and T-cells
How are variable regions of antigen binding sites created by in B-cells and T-cells?
genetic recombination
Clonal selection theory
lymphocytes carry unique receptors
only when there is a match to an antigen are they activated
it is only when the antigen is present and lymphocytes are activated that they undergo clonal expansion
Why do you need booster shots?
Since according to clonal selection theory, lymphocytes only expand when the antigen is present, if the antigen is not presented for long periods of time, you will loose immunity
so you need booster shot to periodically reintroduce the antigen
T-cell activation
- Antigen is presented by dendritic cells and macrophages on MHC protein
- Epitopes bind to grove of MHC protein
- Depending on class of MHC protein, either cytotoxic T-cells or Helper T-cells will be activated
How is T-cell activation an example of the innate and adaptive system working closely together?
antigen is presented to T-cell by dendritic cells and macrophages
these cells are part of the innate immune system
Cytotoxic T-cells
Kill cells that are infected with an extracellular pathogen
Helper T-cell
either activate cytotoxic T-cells or B-cells
B-cell activation
- B-cell binds directly to an epitope on an antigen
- Antigen is internalized and presented on surface of B-cell by MHC proteins
- MHC-protein complex interacts with a helper T-cell
- Helper-T releases cytokines that activate the B-cell
- Activated B-cell divides into plasma cells that produce large quantities of antibodies
What is present in an activated B-cell?
a lot of rough ER to process antibodies to secrete
Antibodies
produced by B-cells
mark pathogens for destruction
Extracellular pathogens
eliminated through a combination of antibody production of plasma cells and activated phagocytosis
antibody production by plasma cells triggers a series of events in the humoral response
Intracellular pathogens
infected cells in the body can advertise their infection by expressing a MHC protein on their surface
T-cells bind to MHC then secrete proteins that pass through the membrane and into the cytoplasm of the infected cell
T-cell detatches and Proteins trigger apoptosis
