A fish cell surface receptor defined by a mAb mediates leukocyte aggregation and deactivation

Area of Science:

• Immunology
• Marine Biology
• Cell Biology

Background:

• Cell adhesion molecules (CAMs) are crucial for inflammatory responses and leukocyte migration.
• CAMs regulate key cellular processes including activation, growth, differentiation, and apoptosis.
• Understanding fish CAMs is vital for comprehending aquatic immune systems.

Purpose of the Study:

• To characterize novel fish cell adhesion molecules involved in immune responses.
• To investigate the function of a newly identified seabream macrophage receptor, Aggregatin.
• To explore the impact of Aggregatin engagement on leukocyte function.

Main Methods:

• Generation of monoclonal antibodies (mAbs) against gilthead seabream (Sparus aurata L.) macrophages.
• Characterization of the Aggregatin receptor using anti-Aggregatin mAb.
• Analysis of Aggregatin-mediated cell adhesion and its functional consequences on phagocytes.

Main Results:

• A 140-kDa cell surface receptor, Aggregatin, was identified on seabream macrophages.
• Anti-Aggregatin mAb induced rapid heterotypic leukocyte aggregation, dependent on Ca(2+), cytoskeleton, and cell metabolism.
• Aggregatin engagement significantly inhibited the phagocyte respiratory burst without inducing cell death or DNA fragmentation.

Conclusions:

• Aggregatin is a novel fish cell adhesion molecule with a role in regulating leukocyte function.
• The findings suggest a potential inhibitory role for Aggregatin in fish inflammatory and immune responses.
• Further research into Aggregatin's function can elucidate fish immune mechanisms and CAMs.