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Induction of target cell apoptosis by channel catfish cytotoxic cells

R J Hogan1, W R Taylor, M A Cuchens

  • 1Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.

Cellular Immunology
|August 17, 1999
PubMed

Insights

Channel catfish effector cells induce target cell apoptosis via a secretory mechanism, not direct cell contact. This research reveals novel cytotoxic pathways in fish immunity.

Area of Science:

  • Immunology
  • Cell Biology
  • Aquatic Animal Health

Background:

  • Peripheral blood leukocytes (PBLs) in channel catfish possess cytotoxic capabilities.
  • Understanding fish immune mechanisms is crucial for aquaculture and comparative immunology.

Purpose of the Study:

  • To elucidate the cytotoxic mechanisms employed by channel catfish peripheral blood-derived effector cells.
  • To determine if catfish effector cells induce apoptosis or necrosis in target cells.

Main Methods:

  • Transmission electron microscopy (TEM) for ultrastructural analysis.
  • [(3)H]thymidine DNA fragmentation (JAM) and TUNEL assays to detect DNA fragmentation.
  • Coculture experiments with allogeneic target cells and calcium chelation (EGTA).

Main Results:

  • Catfish PBLs, specifically agranular lymphocytes, induced apoptosis in allogeneic target cells.
  • DNA fragmentation was observed within 1 hour of coculture, confirmed by JAM and TUNEL assays.
  • Cell lysis was inhibited by calcium chelation, and fixed effectors did not induce cell death, suggesting a secretory mechanism.

Conclusions:

  • Channel catfish peripheral blood effector cells trigger target cell apoptosis through a secretory mechanism.
  • The mechanism appears to involve the release of cytotoxic factors rather than direct cell-surface ligand interactions.
  • This study provides the first evidence of an apoptotic pathway utilized by catfish peripheral blood cytotoxic effectors.

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