Human peripheral nerve macrophages in normal and pathological conditions

Bruno Bonetti, Salvatore Monaco, Caterina Giannini, Sergio Ferrari, Gian Luigi Zanusso, Nicola Rizzuto

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


We investigated, by immunocytochemistry and immune electron microscopy, the immunophenotype, morphology and functional properties of human peripheral nervous system (PNS) macrophages (MΦ) under normal and pathological conditions. Endoneurial MΦ disclosed an elongated, ramified morphology, with the main processes oriented along the major axis of nerve fibers; they shared several lineage-related and functional markers with monocyte/macrophages and central nervous system (CNS) microglia, including CD4, CR3, CR4 and FcRIII. In addition, basal expression of HLA-DR antigens was exclusively confined to MΦ in normal PNS. In the course of unrelated pathological conditions, resident MΦ underwent activation with transformation to hypertrophic cells or foamy phagocytes and up-regulation of the markers expressed in normal conditions; new expression of a macrophagic antigen was detected on activated MΦ. In different neuropathies, HLA-DR expression was also detected on non-myelin forming Schwann cells with ultrastructural features indicative of denervation. The present results demonstrate that the human PNS is provided with an intrinsic population of immunocompetent and potentially phagocytic MΦ, which represent the peripheral counterpart of CNS microglia.

Original languageEnglish (US)
Pages (from-to)158-168
Number of pages11
JournalJournal of the neurological sciences
Issue number2
StatePublished - Sep 1993


  • (Human)
  • Complement receptors
  • HLA-DR expression
  • HLA-DR-positive macrophages
  • Immune electron microscopy
  • Immunocytochemistry
  • Peripheral nervous system
  • Peripheral neuropathy

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology


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