Immune 4 Flashcards
How soluble chemical messengers bind to receptors
- cytokine and chemokine receptors are found on innante and adaptive immune cells
- cytokine binds to cytokine receptor
- signal is told to upregulate or down regulate gene expresses that will help fight the infection that exists
- chemokine helps cells follow a gradient towards inflammation as well as send info to nucleus to up or down regulate gene transcription
Cell surface-bound receptors binding to cell surface-bound ligands
Can alter the function of one or both genes (ADD PICTURE)
Antigen being presented to a cell surface- bound receptor
- innate and adaptive communicate between dendrticitc cells
- allow them to present pieces of antigen - they are phagocytise so they can ingest pathogens and put a piece of pathogen on a molecule and show a bit of pathogen to T cell - if T cell recognises it they can be activated
What is an antigen ?
Anything that has the potential to be recognised by the immune system (not necessarily bad)
What is a foreign antigen
- anything from outside (transplants, pathogens, some chemicals)
What is a self antigen
Immune system usually tolerant of self antigen
- designed to not respond to self antigens
Major immune cell communication methods
- soluble molecules (cytokines or chemokines) binding receptors on a cell membrane
- cell surface-bound receprtos binding to cell surface-bound ligand (on other cells)
- antigen (pathogen parts) being presented to cell surface bound receptors
Activated dendtricic communication with T cells
Activated dendritic cells:
- make cytokines that bind receptors on T cell membranes
- have cells surface-bound receptors that bind to T cell surface bound ligand (or vice versa)
- present antigen to cell surface-bound receptors on T cells
This communication leads to activation of the T cells - it is an example of innate and adaptive immune responses interacting
Two types of MHC
MHC-1 presents endogenous (intracellular) antigenic material, expressed on all nucelated cells.
( - intracellular may be own proteins or viruses/pathogen that escape phagocytosis and are producing proteins within the cell)
MHC-11 presents exogenous (extracelular) antigen, expressed only on antigen presenting cells such as dendritic cells.
( - extracellular is antigen taken up from the outside)
(- only expressed on cells able to undergo phagocytosis - phagocytic cells of the myloid lineage and dendritic cells - dendritic cells are the most important cells for presenting information to our T-cells in this way)
MHC?
- major histocompatibility compatibility complex
- molecule that holds antigen out to T- cell
Helper T cells that have been activated by a dendritic cell can then “help” B cells by…
- making cytokines that bind to receptors on B cell membranes
- have cell surface-bound receptors that bind to a B cell surface-could ligand (or vice versa)
This communication leads to activation of the B cell, and helps the B cell to make antibodies
B cells and compliment
- linking innate and adaptive immunity
- antibody binding to a pathogen can trigger the classical pathway of complement activation
AND - complement fragments that are bound to antigen (pathogen) can also help activate B cells to make antibodies
- these are both examples of how innate and adaptive immunity interact with each other
Summary!
- You break physical barrier (skin)
- Pathogens enters the body
- Chemical mediators lead to vascodilation and entry of phagocytic cells to the tissue to “eat and destroy”
- The complement pathway is triggered - just lectin and alternative (not the classical as the antibody isn’t round yet)
- Dendritic cells in the skin become activated through recognition of pathogen associated molecular patterns (PAMPS)
- Dendritic cells move out of tissue and drain into the local lymph node
- Activated dendritic cells activate T cells via MHC
- Antigen + T cells and compliment activate B cells
- B cells produce antibody
- Complement, phagocytosis and antibodies help clear the pathogen
