Complement receptor 3 (CD11b/CD18) is implicated in the elimination of β-amyloid peptides.

Microglia are the professional phagocytes of the brain and express phagocytic receptors such as complement receptor 3 (CR3 or CD11b/CD18). Using mimics of the amyloid deposit made of heat-killed yeasts coated with either Aβ 1-40 or Aβ 1-42, we were able to study how microglia interacted with and ingested these particles in vitro. We have shown previously that the low density lipoprotein receptor-related protein (LRP) is largely implied in the phagocytosis of Aβ 1-42-opsonized heat-killed yeasts and partly in that of Aβ 1-40-opsonized heat-killed yeasts.

Uptake of Abeta 1-40- and Abeta 1-42-coated yeast by microglial cells: a role for LRP.

Artificial diffuse and amyloid core of neuritic plaques [beta-amyloid peptide (Abeta) deposits] could be prepared using heat-killed yeast particles opsonized with Abeta 1-40 or Abeta 1-42 peptides. Interaction and fate of these artificial deposits with microglial cells could be followed using a method of staining that allows discrimination of adherent and internalized, heat-killed yeast particles. Using this system, it was possible to show that nonfibrillar or fibrillar (f)Abeta peptides, formed in solution upon heating (aggregates), could not impair the internalization of heat-killed yeast particles opsonized with fAbeta 1-40 or fAbeta 1-42.

Low-level iron-dependent mutants of Listeria monocytogenes and their virulence in macrophages.

Listeria monocytogenes is an opportunistic intracellular pathogen capable of growth that requires iron for growth within phagocytic cells and virulence expression. In the presence of an appropriate concentration tropolone, an iron-chelating agent, growth of L. monocytogenes is completely inhibited.