Eosinophil-active cytokine from mononuclear cells cultured with L-tryptophan products: An unexpected consequence of endotoxin contamination

Hirohito Kita, Arthur N. Mayeno, Cornelia M. Weyand, Jörg J. Goronzy, Deborah A. Weiler, Steven K. Lundy, John S. Abrams, Gerald J. Gleich

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Background: The eosinophilia-myalgia syndrome, caused by a contaminant or contaminants in epidemiologically implicated L-tryptophan products, is characterized by eosinophilia and eosinophil degranulation. We hypothesized that immune cells are stimulated by implicated L-tryptophan and produce eosinophil-active cytokines. Objectives: This study was designed to identify substances in L-tryptophan causing the eosinophilia-myalgia syndrome. Methods: Peripheral blood mononuclear cells were cultured with L-tryptophan products, and supernatants were tested for their ability to enhance eosinophil degranulation and survival in vitro and for their cytokine content. Subsequently, 46 different L-tryptophan lots were analyzed for their in vitro biologic activities. Results: After peripheral blood mononuclear cells were cultured with implicated L-tryptophan, their supernatants enhanced eosinophil degranulation and survival. These activities were blocked by anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibody; immunoreactive GM-CSF was measurable in the supernatants. Monocytes, but not T lymphocytes, were the responding cells. However, no correlation was observed between the in vitro biologic activity and lots of epidemiologically implicated L-tryptophan products. This biologic activity in the L-tryptophan products was characterized as endotoxin. Conclusion: Although L-tryptophan products stimulate peripheral blood mononuclear cells to produce GM-CSF, this response is caused by endotoxin contamination of the L-tryptophan products and not by a specific L-tryptophan contaminant. Endotoxin contamination must be considered as a possible cause of eosinophil-active cytokine production by peripheral blood mononuclear cells. (J ALLERGY CLIN IMMUNOL 1995;95:1261-7.).

Original languageEnglish (US)
Pages (from-to)1261-1267
Number of pages7
JournalThe Journal of Allergy and Clinical Immunology
Issue number6
StatePublished - Jun 1995


  • Eosinophilia-myalgia syndrome
  • GM-CSF
  • L-tryptophan
  • cytokine
  • degranulation
  • endotoxin
  • eosinophils
  • survival

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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