Immune-like phagocyte activity in the social amoeba

Science. 2007 Aug 3;317(5838):678-81. doi: 10.1126/science.1143991.


Social amoebae feed on bacteria in the soil but aggregate when starved to form a migrating slug. We describe a previously unknown cell type in the social amoeba, which appears to provide detoxification and immune-like functions and which we term sentinel (S) cells. S cells were observed to engulf bacteria and sequester toxins while circulating within the slug, eventually being sloughed off. A Toll/interleukin-1 receptor (TIR) domain protein, TirA, was also required for some S cell functions and for vegetative amoebae to feed on live bacteria. This apparent innate immune function in social amoebae, and the use of TirA for bacterial feeding, suggest an ancient cellular foraging mechanism that may have been adapted to defense functions well before the diversification of the animals.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Separation
  • Cytoplasmic Vesicles / metabolism
  • Dictyostelium / cytology
  • Dictyostelium / immunology*
  • Dictyostelium / microbiology
  • Dictyostelium / physiology
  • Ethidium / metabolism
  • Fluorescent Dyes / metabolism
  • Gene Expression
  • Immunity, Innate
  • Legionella pneumophila / immunology*
  • Mutation
  • Phagocytes / cytology
  • Phagocytes / immunology*
  • Phagocytosis*
  • Protozoan Proteins / metabolism


  • Fluorescent Dyes
  • Protozoan Proteins
  • Ethidium