Development and characterization of channel catfish long term B cell lines

Area of Science:

• Immunology
• Vertebrate Zoology
• Cell Biology

Background:

• B cell lines are crucial for studying immune responses.
• Ectothermic vertebrates, like fish, have less characterized immune systems compared to mammals.
• Establishing long-term cell lines from non-mammalian vertebrates presents unique challenges.

Purpose of the Study:

• To establish and characterize long-term cloned B cell lines from channel catfish (Ictalurus punctatus).
• To investigate the origin and characteristics of these novel cell lines.
• To assess their potential for studying B cell function and evolution in ectotherms.

Main Methods:

• In vitro lipopolysaccharide (LPS) stimulation of peripheral blood B cells.
• Cloning and continuous in vitro maintenance of cell lines for over 12 months.
• Southern blot analysis for immunoglobulin heavy chain (IgH) gene rearrangements.
• mRNA transcription analysis for VH gene families.
• Flow cytometry for IgM expression (cytoplasmic and cell surface).

Main Results:

• Successfully established diploid, long-term cloned B cell lines from channel catfish.
• Parental cell lines showed polyclonal origin with multiple IgH gene rearrangements and transcription of all VH gene families.
• Cloned cell lines exhibited allelic exclusion, expressing a single VH gene and producing IgM with a single L chain isotype.
• Cells secreted moderate levels of IgM, despite not morphologically resembling plasma cells.

Conclusions:

• These channel catfish B cell lines represent the first established from ectothermic vertebrates.
• They provide a valuable tool for investigating B cell development, Ig gene rearrangement, and allelic exclusion in a non-mammalian model.
• The cell lines offer significant potential for future research into the evolution of adaptive immunity.