Perspectives on antigen presenting cells in zebrafish

• The major APCs, dendritic cells, macrophages, and B cells, have been identified in zebrafish.
• Functional studies indicate that hallmarks of mammalian APC activity are conserved in zebrafish.
• Further research will advance our understanding of how APC function evolved in vertebrate animals.

Antigen presentation is a critical step in the activation of naïve T lymphocytes. In mammals, dendritic cells (DCs), macrophages, and B lymphocytes can all function as antigen presenting cells (APCs). Although APCs have been identified in zebrafish, it is unclear if they fulfill similar roles in the initiation of adaptive immunity. Here we review the characterization of zebrafish macrophages, DCs, and B cells and evidence of their function as true APCs. Finally, we discuss the conservation of APC activity in vertebrates and the use of zebrafish to provide a new perspective on the evolution of these functions.