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Activation of channel catfish B cells by membrane immunoglobulin cross-linking

F W van Ginkel1, N W Miller, M A Cuchens

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

Developmental and Comparative Immunology
|March 1, 1994
PubMed

Insights

Channel catfish B cells activate upon membrane immunoglobulin M (mIgM) cross-linking, showing increased calcium and protein phosphorylation. This suggests conserved signaling pathways between fish and mammalian B cells.

Area of Science:

  • Immunology
  • Fish B cell signaling
  • Comparative immunology

Background:

  • B cells are crucial for adaptive immunity in vertebrates.
  • Mammalian B cell activation via membrane immunoglobulin (mIgM) involves conserved intracellular signaling pathways.
  • Understanding fish B cell activation provides insights into the evolution of the immune system.

Purpose of the Study:

  • To investigate the early activation events in channel catfish (Ictalurus punctatus) B cells upon mIgM cross-linking.
  • To compare the signaling pathways of fish B cells with those of mammalian B cells.

Main Methods:

  • Stimulation of channel catfish B cells with anti-mIgM antibodies.
  • Measurement of intracellular calcium levels.
  • Analysis of protein phosphorylation patterns using tyrosine-specific antibodies.

Main Results:

  • Cross-linking of catfish B cell mIgM induced rapid increases in intracellular calcium levels.
  • Anti-IgM stimulation led to the rapid phosphorylation of intracellular proteins on tyrosine residues.
  • Catfish B cells did not show calcium changes upon lipopolysaccharide stimulation.
  • Phosphorylated proteins suggest the activation of protein tyrosine kinases and potential association with accessory molecules.

Conclusions:

  • Channel catfish B cells exhibit conserved early activation events, including calcium flux and protein tyrosine phosphorylation, upon mIgM cross-linking, similar to mammalian B cells.
  • These findings suggest that fish B cells utilize a conserved signal transduction system for mIgM ligation.
  • The short cytoplasmic tail of catfish mIgM implies association with accessory molecules, potentially homologous to mammalian Ig-alpha and Ig-beta/gamma, for signal transduction.

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