Innate immune system Flashcards
4 āCā chemical components of the immune system
- cytokines - proteins that affect other cells
- Complement - set of plasma proteints that act in cascade to attack extracellular pathogens
- chemokines - small proteins that cause leukocytes to migrate
- coagulation - blood proteins that cause blood clotting
2 functions of immune system
- sentinal - recognize non-self
2. attack
2 primary defence types against path.
- physcial
2. chemical - pH, antimicrobials, ROS
what recognizes bad pathogens
TLRs or PRRs (pattern recognition receptors)
what do TLRs recognize
PAMP - pathogen assoc. molecular patterns
2 places TLR are expressed
- extra - for bact etc.
2. intracellular - for viruses
general steps when TLR binds path.
- send signal to adapter molecule in cell
- kinases signal to nucleaus
- nucleus transcribes genes to deal with danger signal
what is an inflammasome
assembled intracellular complex of proteins that are signalled by phaged paths. and secrete IL-1 for inflammation
what cells phag
neutro, macro, dendritic, B-cells
4 main receptors on a macrophage
- Fc
- TLR
- mannose
- complement
what does phagocytosis lead to (3)
- initiation of bactericidal activities
- antigen presentation for T-cells
- induciton of pro-inflammatory cytokine reslease
4 mechs. other than phag t deal with a path.
- complement cascade
- ADCC - antibody dep. cellular toxicity
- defensins - anti-microbial peptides on mucous
- pentraxins - bind path. and act as a signal
3 different outcomes of completment activation
- recruitment on inflamm. cells
- opsinization
- killing of paths
what is ADCC - antibody dep. cellular toxicity
NK cells killing of paths. that have been opsinzed by surface bound antibodies
what are 3 first innate cells that will deal with an infection
- tissue sentinal cells - secrete cytokines
- neutophils - short-lived dedicated killers
- macrophages - supress neutophils and come in and clean up
3 ways neutrophils kill
- phag.
- degranulate
- netting
3 main pathways of complement activation
- classical - antibody depenedent
- lectin - lectin binding to path surfaces
- alternative - pathogen surfaces
what is main complement of complement activation
C3 convertase to C3a and C3b
what is function if C3a
small frag that cause increased vasc. permeability and inflammation
what is funciton of C3b
tags bacteria for phag - opsinization
what happens in C3 conversion
breaks into 2 peices (a and b)
how does C3b opsinize
bound C3b frag is recognized on phag. cell
what is early component of compliment system
C1 binding to antibodies
what is late component of compliment system
- C3 convertase > C5 convertase
- leads to membrane attack complex (MAC attack)
- pokes small pore in membrane and leads to explosion
what else does complement do aside from recognize paths
recognizes damage host cells to elim. danger
what happens if def. in early components
not severe - assoc. with lupus
what happens if def. in late components
more nesseria infections
what happens if def. in C3
recurrent pyogenic infections -M and M
3 places where complement is regulated
- at C1 conversion
- C3 convertase
- late phase
what is hereditary angioneurotic edema
C1INH (inactivtate C1) deficiency leads to too much active C1 and get excessive response
what is febrile neutropenia
severe lack of neutrophils and get infected easily
