Identification of inducible nitric oxide synthase in human macrophages surrounding loosened hip prostheses

Simon C. Watkins, William Macaulay, David Turner, Richard Kang, Harry E. Rubash, Christopher H. Evans

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Exposure of rodent macrophages to certain cytokines and endotoxin results in the synthesis of inducible nitric oxide synthase (iNOS or NOS-II) leading to the production of large amounts of nitric, oxide (NO). Cultures of human macrophages, in contrast, do not produce iNOS after cytokine stimulation, and their ability to act as a physiological source of NO remains questionable. Here we have used immunohistochemistry and in situ hybridization to demonstrate the presence of iNOS within human macrophages present in the interfacial membrane and pseudocapsule that surround failed prosthetic hip joints. Synovial tissue recovered from normal human joints did not express iNOS. Many of the iNOs-positive macrophages within the interfacial membrane had phagocytosed large amounts of polyethylene wear debris, suggesting a role for phagocytic stimuli in inducing iNOS in human macrophages. These findings additionally support a role for NO in modulating the localized bone resorption that accompanies the aseptic loosening of prosthetic joints.

Original languageEnglish (US)
Pages (from-to)1199-1206
Number of pages8
JournalAmerican Journal of Pathology
Issue number4
StatePublished - 1997

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


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