Innate Immunity Flashcards
What are the four main functions of the innate immune response?
- complement activation
- inflammation
- cell activation
- priming of the adaptive immune response
What is the basis for the innate imune response? What is the body trying to do?
The basis is the recognition by TLRs of PAMPs and DAMPS (or host cells that don’t have the appropriate markers) and signal phagocytosis of those cells
What are defensins and cathelicidins?
THey are small antimicrobial peptides that are produced in cells of the physical barrier - mostly epithelial cells but some leukocytes as well
How do defensins and cathelicidins differ structurally?
cathelicidins are alpha helical peptides while defensins are beta strand peptides connected by disulfide bonds
How do defensins and cathelicidins promote bacterial dcell death?
They carry positive charges that interact with the cell membrane components, then once they integrate in the membrane they dimerize and pull the membrane apart to increase cellular permeability, resulting in cell death
Stimulation of the TLRs by PAMPS or DAMPS results in activation of the “mother of all immune system tranxcription factors” which is…
NF-KB
the MyD88 depentent pathway is common to all TLRs except for…
TLR3
What are the three distinct pathways that are common to TLR signalling?
- MyD88 dependent production of inflammatory cytokines
- MyD88 dependent production ofINF-alpha
- MyD88 INdependent produciton of INF beta and maturation of dendritic cells
While C3b, C4b and C5b of complement bind to the membrane of invaders, what do the “a” components do?
They act as chemotactic factors and activate PMN and macrophage degranulation
If C3b and C4b bind to host cells, what inactivates them?
decay-accelerating factor (DAF)
WHat are the hallmarks of inflammation?
influx of fluid (edema), increased temp, local hypoxia, influx of white blood cells
When C5a triggers basophils and mast cells to degranulate and activate, what inflammatory mediators are released?
histamine (increase permeability), PGE2 (vasodilation and permeability), leukotriene D2 (neutrophil chemotaxis), Leukotriend D4 (permeability)
What cytokines are released from macrophages and what do they do?
- TNF - cause fever, stimulate E selectin expression
- IL-2 - pyrogen, stimulate expression of E selectin
- IL-8 - chemotaxis
How do the cell populations differ in acute vs chronic infection
acute: more neutrphils and activated T helpers
chronic: more macrophages, cytotoxic T cells and B cells
What three cytokines are the most important inflammatory cytokines?
IL-1, TNFalpha and IFNgamma