immunity Flashcards
molecular arms race
as animal immunity adapts and escapes the threat by a pathogen, the pathogen evolves
CRISPR
found in genome of prokaryotes
used to detect and destroy prokaryote DNA
Cas9 cleaves out segements
self vs nonself
self - things that belong within an animal’s body
nonself - things that should not be in an animals body
recognized through protein interaction
sponge immunity
no apparent immune cells
is capable of recognizing self from nonself
antigen
any chemical compound - protein, peptide, fat, nucleotide or carbohydrate, which is recognizable by an animal’s immune system
antigen constraints
> 4000 Mw
proteins > sugars > lipids > nucleic acids
epitopes on large structures
how do animals destroy antigens?
encapsulation
aggregation
lyse
chemical attack
phagocytosis
Pathogen Associated Molecular Pattern (PAMPs)
lipopolysaccharides (LPS) and peptidoglycans on the surface of pathogens or protein flagellin
microbiomes
occupy all prokaryote-adhesion sites on epithelial surfaces; depriving pathogens a seat at the table
gives immune system a chance to develop defenses against non-pathogen
allorecognition
antigen recognition by an immune cell
CD57 receptor
found in sponges
has an external, antigen-binding hypervariable region
hypervariable region
same protein, same gene, amino acid sequence is shuffled to give trillions of possible combinations
Toll-Like Receptors (TLRs)
usually expressed on the surface of phagocytes
recognizes PAMPs
signal activated inside cell
Leucine-Rich Repeats (LRRs)
20-30 LRRs within TLR
binds to PAMP and other nonself antigens
activation of toll-like receptor
PAMP binds to LRR, resulting in allosteric coupling and activation of MyD88
MyD88 activates IRAk
IRAk phosphorylates TRAF6
TRAF6 phosphorylates IkK (degraded)
NFkB activation - gene suite
DSCAM
down’s syndrome cell-associated molecule
insects and crustaceans
chemical agents
reactive chemical species (ROS and NOS)
effector molecules
poisons!
fibrinogen and phagocytes
peptides and chemicals
antimicrobial peptides
lysozyme (vertebrates)
phagocyte properties
encapsulation
microbicidal
lysis
repair
phagocytosis
alarm
cytokines
signaling molecule found in vertebrates and invertebrates
transcription factors and hormone-like properties
inflammation
vasodilation - increasing blood flow and immune cells
chemotaxis - attraction of phagocytes to area from blood into tissues
permeability - allows large proteins to enter area
fever
homeothermic endotherms - increase in Tc above normal
heterothermic ectotherms - behavior increase in Tc by movement, increased activity
benefits of fever
200-fold reduction in bacterial growth
improved immune response
increased phagocytic activity
inflammation suppression
ion sequestering
increased TLR expression
innate immunity
response is always the same, stereotypic
present in all animals
main aspect - SKIN
adaptive immunity
memory component and response toward an antigen
innate functions
cell recruitment to site of infection via cytokine signaling
activation of complement cascade
identification and removal of foreign substances
physical and chemical barriers
RAGs (recombination-activating genes)
cutting, separating, and recombining
dsDNA breaks at specific sites and a unique way of coupling them through VDJ recombination
lymphocytes
“white blood cells”
single, large nucleus, small amount of cytoplasm, proteins expressed on surface
T-lymphocytes and B-lymphocytes
T-memory
carry memory of exposure to specific antigen
clonal growth
T-helper
regulate activity of other T-lymphocytes
secrete cytokines to mature B-lymphocytes and activate Tc-lymphocytes and macrophages
T-helper
regulate activity of other T-lymphocytes
secrete cytokines to mature B-lymphocytes and activate Tc-lymphocytes and macrophages
T-cytotoxic
secrete pathogen-destroying chemicals
T-regulatory
suppress T-lymphocyte induced immunity
crucial for maintenance of immunological tolerance
TcR (T-cell receptor)
hypervariable antigen binding region
types of B-lymphocytes
Naïve B
Memory B
Plasma B
BcR
hypervariable antigen-binding region
positive selection
removal of all cells (and receptors) that don’t work properly
negative selection
removal of all cells (and receptors) that recognize self antigens
major histocompatibility complex (MHC)
cell molecular footprint – ID tag
each animal is unique because of genetic variability, polygenic
class MHC I
almost all vertebrate nucleated cells
checking IDs
class MHC II
surface of macrophages and B lymphocytes
eats what doesn’t belong
