Evolution of Immune Systems

1
Evolution of Immune Systems
2
Brunet, 1950 Immunity The ability to
differentiate between self and non-self
3
MHC-type Proteins are Present in all Metazoans

• Porifera have polymorphic MHC genes with
  multiple loci
• MHC have no structural similarities to vertebrate
  MHC - proteoglycan complex

4
Host Defence Systems in Invertebrates

• Phagocytosis Developed from procaryotic feeding
  mechanism Phagocytes present in all phyla
• Encapsulation Coelomocytes form a capsule around
  larger foreign bodies
• Antibacterial peptides Non-specific response -
  no capacity for modulation Probably ubiquitous

5
Lectins

• Antibacterial proteins
• Bind to sugar residues on microbe surfaces
• Tagg microbes, which attracts coelomocytes
• At least in vertebrates, lectins are sitting as
  receptors on the cell surface of neutrophils.
  Endothelial cells close to the infected tissue
  are producing R-Selectin, a transmembrane
  glycoprotein that bind lectins and activate the
  neutrophils