Innate Immunity Flashcards
Which part of the LPS is antigenic: the hydrophobic lipid rich end or the hydrophilic polysaccharide end? What is this part called?
polysaccharide end, called the O antigen
In which part of LPS does endotoxicity reside: O-antigen or Lipid A region?
Lipid A
What are symptoms of gram neg. septic shock?
hypovolemic shock (decreased bp and CO), disseminated intravascular coagulation, acute respiratory distress syndrome
What are the primary mediators of septic shock? What are they secreted by?
TNF alpha and IL-1 secreted by macrophages
What in vitro test can be used to measure for endotoxin?
Limulus amebocyte lysate, use cascade of enzymes found in horseshoe crab’s primitive macrophages to test for presence of endotoxin
How does TNF alpha mediate responses to endotoxin?
activates vascular endothelium and increases vascular permeability, increased entry of complements and cells to tissues, causes shock
How does IL-1 mediate responses to endotoxin?
activates vascular endothelium, activates lymphocytes, local tissue destruction, increases access of effector cells, causes fever and IL-6 production
What does IL-6 do in septic shock?
fever, induces acute-phase protein production by hepatocytes
What is a toll-like receptor?
- stimulated by many different ligands from bacteria or DNA motifs of bacteria
- LPS, peptidoglycan, yeast, and mycobacterium can all bind it and induce same cytokine production
What else can stimulate TLR?
- protozoa parasites (such as falciparum) that induce TNF alpha
- leishmaniasis and trypanasomal infection
- super antigens
What bacteria is TSS caused by?
S. aureus
What is the cause of sterile sepsis?
TSS, symptoms look like gram - sepsis but is from an exotoxin
How does LPS bind?
CD14 binds LPS to bring it to the surface. TLR-4 specifically binds LPS that is bound by CD14
