Unit 2: Week 2 Flashcards
(35 cards)
Approximately how long after the innate immune response does the adaptive immune response begin?
3-4 days
Name 3 cells that present MHC II.
Macrophages
Dendritic cells
B-cells
When a dendritic cell has TLR recognition of a pathogen, what molecule is upregulated on its surface?
B7.1/B7.2
Identify the co-stimulatory molecules on the surface of a naive CD4+ T-helper cell.
T-cell receptor
CD4
CD28
CD40Ligand
How do most T-cells enter the lymph node?
Via high endothelial venules
Describe the step by step process of T-helper cell activation by a dendritic cell presenting antigen.
- T-cell receptor recognises the antigen
- CD4 binds to MHCII
- B7.1/B7.2 bind to CD28
- This unregulates CD40L on the T-cell surface
- CD40L binds to CD40
- Dendrite secretes a polarising cytokine
- T-cell secretes IL-2 as an autocrine to induce proliferation
What is T-cell anergy and why does it occur?
Inactivation of T-cell when a dendritic cell presents without B7.1/B7.2 (because there was no TLR recognition of pathogen).
Prevents an immune response to phagocytic cells that present self molecules that are not pathogen.
What polarising cytokine and transcription factor are responsible for Th1 T-helper cells?
IL-12
T-bet
What is the product of Th1 T-helper cell and what effect does this have?
IFN-gamma (+ IL-12)
Activates macrophages
During B-cell activation, which cell is presenting antigen?
The B-cell; T-cells cannot present antigen
Describe the Th2 T-helper cell response.
Non-inflammatory
Change macrophages to promote tissue repair
Directs barrier immunity
IL-13 induces goblet cell production of mucus
IL-5 recruits eosinophils
What is the polarising cytokine responsible for Th2 T-helper cells?
IL-4
How do CD8+ cytotoxic T-cells cause cell death?
Perforins + granzymes
What else must be bound to a dendritic cell to activate CD8+ cytotoxic T-cells?
CD4+ T-Helper cell
Upregulates co-stimulatory molecules on surface of CD8+ cytotoxic T-cells and secretes IL-2 to facilitate CD8+ cytotoxic T-cell proliferation
Why is cross presentation necessary on dendritic cells?
So CD8+ cytotoxic T-cells can be activated.
Dendrites must bind CD8+ cytotoxic T-cell and CD4+ T-helper cell at the same time for CD8+ cytotoxic T-cell to be activated.
What do MHC I presenting cells bind to in the lymph node?
CD8+ cytotoxic T-cells
Name 3 unique components of the mycobacteria tuberculosis cell wall.
Mycolic acid (hydrophobic lipid shell)
Cord factor (toxic to mammalian cells)
Wax-d
Why does TB infection require prolonged exposure?
A large number of bacteria are needed to establish and infection.
Cilia + mucus (mucociliary escalator) clears a majority of the bacteria from the upper respiratory tract, preventing the bacteria from infecting macrophages in the lower respiratory tract.
How does mycobacteria tuberculosis stop phagocytosis by macrophages?
Blocks lysosomes formation
What happens to macrophages after prolonged exposure to TNF-alpha?
They turn into epitheloid macrophages or foam cells
Is a primary granuloma tight or loose?
Loose
How does mycobacteria tuberculosis ensure being phagocytosed by macrophages?
Coats itself in C3b and mannose
What is the effect of TNF-gamma on macrophages?
They turn into giant cells or increase their secretion of NOS and reactive O2 species
What is unique about a secondary granuloma in a mycobacteria tuberculosis infection?
Caseating necrosis
