Visualization of neutrophil extracellular traps and fibrin meshwork in human fibrinopurulent inflammatory lesions: I. Light microscopic study

Kazuya Shiogama, Takanori Onouchi, Yasuyoshi Mizutani, Kouhei Sakurai, Ken Ichi Inada, Yutaka Tsutsumi

Research output: Contribution to journalArticle

10 Citations (Scopus)


Neutrophil extracellular traps (NETs) are extracellular fibrillary structures composed of degraded chromatin and granules of neutrophil origin. In fibrinopurulent inflammation such as pneumonia and abscess, deposition of fibrillar eosinophilic material is a common histopathological finding under hematoxylin-eosin staining. Expectedly, not only fibrin fibrils but also NETs consist of the fibrillar material. The aim of the present study is to analyze immunohistochemically how NETs are involved in the inflammatory process. Archival formalin-fixed, paraffin-embedded sections accompanying marked neutrophilic infiltration were the target of analysis. Neutrophil-associated substances (citrullinated histone H3, lactoferrin, myeloperoxidase and neutrophil elastase) were evaluated as NETs markers, while fibrinogen gamma chain was employed as a fibrin marker. Light microscopically, the fibrils were categorized into three types: thin, thick and clustered thick. Lactoferrin represented a good and stable NETs marker. Thin fibrils belonged to NETs. Thick fibrils are composed of either mixed NETs and fibrin or fibrin alone. Clustered thick fibrils were solely composed of fibrin. Neutrophils were entrapped within the fibrilllar meshwork of the thin and thick types. Apoptotic cells immunoreactive to cleaved caspase 3 and cleaved actin were dispersed in the NETs. In conclusion, NETs and fibrin meshwork were consistently recognizable by immunostaining for lactoferrin and fibrinogen gamma chain.

Original languageEnglish
Pages (from-to)109-116
Number of pages8
JournalActa Histochemica et Cytochemica
Issue number4
Publication statusPublished - 01-01-2016


All Science Journal Classification (ASJC) codes

  • Pathology and Forensic Medicine
  • Biochemistry
  • Physiology
  • Histology
  • Cell Biology

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