Characterization of the putative avian CD2 homologue

Area of Science:

• Immunology
• Comparative immunology
• Avian immunology

Background:

• CD2 is a crucial cell surface receptor on T lymphocytes.
• Understanding CD2 conservation across species aids in deciphering immune system evolution.

Purpose of the Study:

• To identify and characterize the chicken homologue of the mammalian CD2 antigen.
• To investigate the structural and functional conservation of CD2 between avian and mammalian species.

Main Methods:

• Development of mouse monoclonal antibodies (mAbs) against chicken CD2.
• Immunoprecipitation and Western blotting to determine protein size and characteristics.
• Peptide-based antiserum for cross-species epitope mapping.
• Analysis of CD2 expression during chicken thymocyte development.
• Functional assays measuring DNA synthesis in response to anti-CD2 stimulation.

Main Results:

• Two mouse mAbs specifically recognized a ~40,000 Mr chicken CD2 antigen.
• Endo-beta-N-acetylglucosaminidase F treatment revealed a core protein size of ~25,000 Mr.
• A rabbit antiserum against a conserved cytoplasmic peptide cross-reacted with chicken CD2, indicating epitope conservation.
• CD2 expression was detected on chicken thymocytes starting at embryonic day 11.
• Thymic gamma delta T cells were CD2-positive, while most peripheral gamma delta T cells were CD2-negative.
• Anti-CD2 mAbs combined with PMA induced DNA synthesis in chicken T cells, demonstrating functional conservation.

Conclusions:

• The identified chicken molecule is a structural and functional homologue of mammalian CD2.
• CD2 plays a conserved role in T cell activation and development across vertebrates.
• This study provides a valuable tool for avian immunology research.