Innate Immunity Flashcards
What are the dicision centers of the Immune System?
Secondary Lymphoid Tissues (Lymphnodes and Spleen)
Why are afferent and efferent immune responses so much slower than those of the nervous system?
How long does it take?
Both afferent and efferent mediated by cellular migration
(delivery of information to decision center => effector cells destroy infected cells)
=> take up material and deliver it to secondary lymphoid tissues
=> ideally only very specific response
Ca. one week
What are DAMPS and PAMPS?
danger/pathogen associated molecular patterns
What difficulty pose pathogens to the immune systems
Structurally often completely unrelated, various sizes
The hematopoietic system
Immune cells develop from hematopoietic progenitor/stem cells from bone marrow
one part gives rise to lymphocytes (effector cells => antibodyproducing, killer etc) and one lineage is the myloid lineage that produces cells to react early on or communicate (macrophages, granulocytes, monocytes)
Dendritic cells from both lineages
Erythrocytes from own lineage of hematopoietic system
Where are secondary lymphoid tissues
Lymphnodes (all over body => bc slow transduction, except for limps)
Spleen for “filtering” of blood
Tonsils, directly under mucosa of side where pathogens come in
What is the structure of secondary lymphoid tissues?
Afferent lymph vessels: where dendritic cells (detect dangers) come in
T-cell areas: T-cells come from bloodstream into areas, where dendritic cells present information to them
What are Peyer’s Patches
Secondary lymphoid tissues in the gut => detect infection in gut lumen
What are cytokines?
Small Signaling proteins that interact with receptors
Dendritic cells
form net => catch pathogens with cell protrusions
have strong migratory ability, migrate at increased frequency
upregulate co-stimulation of T-cells during migration
present information on MHC molecules
What signals do the dendritic cells transmit?
• activating conditions under which it has encountered the virus
• bits and pieces of pathogen for T-cell activation
What molecules on the surface of dendritic cells elicit T-cell responses?
MHC class II (present peptide fragments), co-stimulators, cytokines (teach immune cells which response to make)
Where are dendriric cells set up?
Basically everywhere:
e.g. on skin, but also underneath in dermis and even secondary lymphoid tissues
Which cells can dendritic cells activate?
Adaptive lymphocytes like T-cells
Innate lymphocytes e.g. NK cells
(receive information back => amplification of signals)
The Toll-like receptor signaling pathway
NFkB transmits signals from TLR downstream
(in fly: Toll receptor) => conserved
System leads to activation of cytokines and leukocytes
Different TLRs for…
different PAMPS/ different pathogens
Where are TLRs located?
At cells surface (bacterial)
In vesicular particles (viral) detect DNA and RNA of visuses when exposed (after uncoating)
In cellular compartments are even more other receptors
Inflammasome
Nod-like receptor (e.g. NLRP3)
=> cell reacts strongly to recognition by ligand for these receptors?
Non-activated cells: protein completely dispersed
Activated: Aggregation to signaling platform => cleave cytokines (for cellular communication)
DAMPS in tumors
DNA damage and DNA leakage from mitochondria into cytosol allows for perception by dendritic cells
DAMPS derive from intracellular structures but are mislocated
What are Antigens?
Pathogen or Tumor cell fragments
How can conditions under which antigens are acquired be sensed?
Molecular pattern recognition receptors on dendritic cells
E.g. by Toll-like receptors (diff receptors for diff pathogens)
What does it mean that a dendritic cell matures?
That it is activated
=> upregulation of co-stimulation and cytokine production for T-cell activation in lymph node
Which parts of the cell are monitored by PRRs?
All cellular compartments
What function do cytokines have in dendritic cells besides activation of T-cells
Prevent dendritic cells from getting infected before they reach lymphnodes to activate lymphocytes
=> there they die => memory of the encounter by activation of lymphocyte
