PATH Immune lecture 1 Flashcards
Describe three constitutive barriers to infection
Skin
Mucosal surfaces
Commensal bacteria
Explain how the skin prevents infection
Skin:
tightly packed keratinised cells prevents colonisation by microorganisms
Low pH, low oxygen tension
Sebaceous glands:
Hydrophobic oils repel
microorganisms
Lysozyme destroys bacterial cell wall
Ammonia and defensins have antimicrobial properties
Explain how mucosal surfaces prevent infection
Mucous traps pathogens
IgA prevents bacteria/viruses attaching to epithelial cells
Lysozyme kills invading pathogens
Lactoferrin starves invading bacteria of iron
Explain how commensal bacteria prevent infection
Compete with pathogenic microorganisms for scarce resources
Produce fatty acids that inhibit the growth of pathogens
Describe the components of the innate immune system
Where are polymorphonuclear cells produced
Bone marrow, then migrate rapidly to the site of infection
List some polymorphonuclear cells
Neutrophils, eosinophils, basophils
What receptors do PMN cells contain and why?
Fc receptor to bind to Ig
What do monocytes and macrophages do?
Circulate in the blood and migrate to where needed, where they differentiate into macrophages
Present antigen to T cells
What do you call a macrophage in the liver?
Kupffer cell
What do you call a macrophage in the spleen?
Sinusoidal lining cell
What do you call a macrophage in the kidney?
Mesangial cell
What do you call a macrophage in the bone?
Osteoclast
What do you call a macrophage in the lung?
Alveolar macrophage
What do you call a macrophage in the neurons?
Microglia
What do you call a macrophage in the skin?
Langerhans cells
What do you call a macrophage in the connective tissue?
Histiocyte
Explain how phagocytes are recruited to a site
Cell damage and bacterial products trigger local production of inflammatory chemokines and cytokines; causing vascular endothelial permeability. CHEMOKINES attract phagocytes
How does the body pick up a pathogen?
PAMPS - pathogen associated molecular patterns - are picked up by TLRs and mannose receptors
PahWhat helps with endocytosis of pathogens? List three types
Opsonisation:
Ab bound to Fc receptors
Complement binding to complement receptors like CR1
Acute phase proteins (CRP)
