Chapter 2 Vaccine Immunology Flashcards
(42 cards)
Describe overall how vaccines induce protection against disease.
They induce effector mechanisms capable of rapidly controlling replicating pathogens or inactivating their toxic components.
Name three (3) effector mechanisms induced by vaccines.
- Production of antibodies by B-cells
- Cytotoxic CD8+ T-cells
- CD4+ helper T-cells (Th cells)
Name five (5) types of helper T-cells.
- Th1 cells
- Th2 cells
- Th17 cells
- Tfh cells
- Treg cells
What type of antigen elicits a T-independent immune response?
Capsular polysaccharides.
What is the hallmark of a T-dependent antibody response?
Induction of higher affinity antibodies and immune memory.
Define adjuvant.
Any agent that increases the stimulation of the immune system through enhanced antigen presentation and/or costimulation signals.
What is the most common adjuvant used in today’s vaccines?
Aluminum salts.
Define antibody affinity.
Strength of the binding interaction between the antibody and a specific epitope at the surface of an antigen.
Define antibody avidity.
Sum of the epitope-specific affinities of an antibody for a given antigen.
What is the main processes underlying affinity maturation in B cells?
Somatic hypermutation and affinity-based selection.
Define antigen-presenting cell.
Any cell that :
- Captures antigens by endocytosis or phagocytosis
- Process them into small peptides
- Display them at their surface through MHC molecules
- Provide costimulation signals that synergistically activates T-cells
Name three (3) antigen-presenting cells.
- B cells
- Macrophages
- Dendritic cells (only ones capable of activating naïve T cells)
What three (3) main cytokines are secreted by Th1 cells?
- IL-2
- IFN-gamma
- TNF-beta
What cells of the immune system are supported by Th1 cells?
- Cytotoxic T cells
- Macrophages
What five (5) main cytokines are secreted by Th2 cells?
- IL-4
- IL-5
- IL-6
- IL-10
- IL-13
What cells of the immune system are supported by Th2 cells?
B lymphocytes.
What effector mechanism is directly induced by Th2 cells?
Extracellular antimicrobial functions, mainly against parasites.
What four (4) main cytokines are secreted by Th17 cells?
- IL-17
- IL-21
- IL-22
- IL-26
What is the main immune function of Th17 cells?
Defense against extracellular bacteria colonizing and/or invading exposed surfaces (mucosa, epithelia, skin).
Define central memory T cells (T_CM).
Memory T cells that traffick through lymph nodes and that are ready to proliferate and generate a high number of effector cells in response to specific microbial peptides.
What is the main function of dendritic cells?
Constantly patrol and sample their surroudings for pathogens.
Define effector memory T cells.
Memory T cells that patrol the body to detect specific microbial peptides and that are capable of an immediate cytotoxic function.
What are the four (4) main functions of Tfh cells?
Help follicular B lymphoctes to :
- Perform isotype switching
- Perform affinity maturation
- Undergo affinity-based selection
- Differentiate into plasmocytes or memory B cells
Define isotype switching.
Switch of Ig surface expression and production by B cells from IgM to IgG, IgA or IgE that occurs during B-cell differentiation through DNA recombination.