Search for immunosuppressive substances produced in the culture of enteric bacteria isolated from marine fish

Hitoshi Ohmori, Masayuki Raitoh, Mikiya Harano, Toshiyuki Oda, Masaki Hikida, Ryosuke Sugihara, Kazunaga Yazawa

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Culture supernatants of enteric bacteria isolated from the gastrointestinal tracts of two marine fishes were screened for the production of immunosuppressive substances. At least 50% of the 60 bacterial isolates tested were found to produce immunosuppressants that significantly inhibited the induction of cytotoxic T cells (CTL) in vitro. The strains that secreted the highest suppressive activity was identified as Aeromonas caviae. The immunosuppressive substance purified from the A. caviae culture supernatant was a polysaccharide with a molecular weight of about 70 kDa that contained mannose : glucose (4:1). This polysaccharide did not show nonspecific cytotoxicity, and was found to inhibit the proliferation and differentiation of CD8-positive CTL.

Original languageEnglish
Pages (from-to)117-119
Number of pages3
JournalJournal of Fermentation and Bioengineering
Issue number1
Publication statusPublished - 1998
Externally publishedYes



  • Cytotoxic T cells
  • Fish enteric bacteria
  • Immune suppression
  • Polysaccharides

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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