Adaptive Immunity Flashcards
What is activation?
order of events where a resting lymphocyte is stimulated to divide and produce progeny specific for a particular Ag
What do B and T cells recognize?
- B cells: macromolecules
- T cells: peptide fragments presented by APCs
How do lymphocytes recognize microbes?
- capture by dendritic cells
- Ags are concentrated in secondary lymphoid organs
- lymphocytes sit and wait in secondary organs
- dendritic cells enter and lymphocytes are activated
What are the roles of dendritic cells?
- capture Ag
- activation
- migration
- display Ag on dendritic cell surface to lymphocytes
What is the result of dendritic activation?
- dendritic cells change from capturers to stimulators
- Ags taken to lymph nodes
- Ags enter lymph nodes where they see lymphocytes
- dendritic cells present Ags
What are the 2 types of APCs?
dendritic and macrophages
How does the adaptive immune system get activated?
dendritic cells
How do T and B cells meet?
- T cells become activated; clonal selection occurs
- moves to follicle; Ag becomes activated and moves to T cell
- T and B cell interact -> help
- goes back to follicle -> has dendritic cell, T cells, B cell & more activation
When cross presentation occur?
when exogenous Ags are present in MHC class 1
What is the importance of cross-presentation?
- vaccinations
- IR -> tumors
- IR -> viruses
When B cells become activated what do they proliferate into?
- plasma cells -> secrete Abs
- memory B cells
What are the 2 pathways for B cell activation?
- T independent -> recognize LPS, nucleic acids; IgM involved
- T dependent -> activated by helper T cells (allows for isotype switching)
What is required for the activation of T cells?
B7 on APCs interact with CD28 on T cells
What is required for the inhibition/downregulation of T cells?
B7 on APCs interact with CTLA-4 on T cells
What is required for the activation of B cells?
- CD40L from T cells interact with CD40 on B cells
- cytokines from T cells interact with cytokine receptors on B cells
