Flashcards in Chapter 3 Deck (290)
Where do macrophages derive from?
progenitor cells that enter tissues during emrbyonic development and self-renew or from circulating monocytes
Where do the embyronic progenitors of macrophages derive from?
fetal liver; yolk sac or the aorta-gonad-mesonephros
What cytokine does self-renewal of microglial cells and Kupffer cells rely on?
What receptor do classical monocytes express?
What receptors do patrolling monocytes express?
CD14 and CD16
What are the 3 methods by which pathogens can be taken into the cell?
phagocytosis; receptor-mediated endocytosis and macropinocytosis
What are the phagocytic receptors present on macrophages and neutrophils?
C-type lectin family; scavenger receptors; complement receptors; Fc receptors
what is the function of dectin-1?
recognises b-1,3-linked glucans
What cells are b-1,3-linked glucans found on?
Which cells express mannose receptor?
macrophages and denritic cells
What does the mannose receptor recognise?
What is thought to be the function of mannose receptors?
mainly as a clearance recpetor for host glycoproteins which have mannose containing side chains and whose extra-cellular concentrations are raised during inflammation
What do scavenger receptors recognise?
anionic polymers and acetylated low-density lipoproteins
Give an emaple of a GPCR involved in pathogen recognition and killing?
fMet-Leu-Phe receptor ; Chemokine receptors
What amino acid usually initiates protein synthesis in bacteria?
What happens when fMLF binds its ligand?
activates intracellular signalling that direct the cell to move toward th e most concentrated source of hte ligand; induces production of ROS in the phagolysosome
What proteins are activated in response to f-Met-Leu-Phe activation?
Rho family of small GTAse proteins: Rac and Rho
What is the function of Rac in the assembly of NADPH oxidase?
promotes the movement of cytosolic compoenets of the enzyme to the phagolysosomal membrane and assmble the full enzyme
what is the function of NADPH oxidase?
generates superoxide- a reactive oxygen species (NAPH---NAP+ and H+)
What does the NADPH oxidase reaction cause?
a transient increase in oxygen consumption by the cell:respiratory burst- as the electron from NADPH oxidase reaction is transferred to oxygen
What does the respiratory burst cause?
generates superoxide anion within the lumen of hte phagolysosome
What enzyme converts the superoxide anion into hydrogen peroxide?
What disease results from a genetic deficiency of NADPH oxidase?
chronic granulomatous disease
What type of infection are patients with CGD particularly susceptible to?
bacterial and fungal infections
What receptors synergise to activate Rac?
phagocytic recpetors and fMLF or C5a
How is the pH decreased in the phagolysosome?
potasssium and hydrogen ions are drawn into the phagolysosome to neutralise the charged superoxide ion
What does NET formation rely upon?
generation of ROS
What are monocytes attracted to a site of inflammation and activated called?
How are monocytes distinguished from macrophages?
monocytes lack of expression of the adhesion GPCR E1- F4/80