Adaptive Immunity Flashcards
What is required for T-cell activation?
- Signal 1 – TCR binding of Ag:MHC complex on host cell.
- Signal 2 – Binding of co-stimulatory molecules (e.g. CD80, CD86)
- Signal 3 – Cytokines secreted by the APC (e.g. IL-12)
When is the adaptive immune system activated?
When an infection can’t be controlled by an innate immune system
What 2 cells are involved in producing effector functions?
B-lymphocytes (B-cells) and T-Lymphocytes (T-cells)
What is antigen presentation?
The communication between innate and adaptive immune systems
What are MHC’s?
They attach to certain antigens
What are the 2 types of MHC’s?
MHC Class I: presents self antigens and antigens from cytoplasmic pathogens and peptides to CD8 T cells.
MHC Class II: present foreign antigens and present peptides to CD4 T cells
What are the major antigen presenting cells?
Dendritic cells, macrophages, B cells
Where do T and B cells arise and mature?
B cells: bone marrow
T cells: bone marrow and then thymus to mature.
What are the T cell effector functions?
Cytotoxic T cells (CD8) kill host cells that are infected
Helper T cells (CD4): provide additional signals that help activate antigen-stimulated B cells to make antibodies and macrophages to kill intracellular pathogens.
Regulatory T cells (CD4): suppress the activity of other lymphocytes to regulate the immune response
What are the antibody effector functions?
- Neutralization
- Opsonization
- Compliment Activation
How does B Cell activation occur?
Signal 1: binding of antigen by the BCR
Signal 2: accessory signals from T-helper cells.
- CD40L interaction
How does antibody formation occur?
Signal 1: physical contact with Th cell
Signal 2: cytokines induce isotype switching (IL4,IL5, IFN-y,TGF-B)
