The Avian Macrophage in Cellular Immunity

This chapter describes the identification and characterization of avian macrophages relative to their mammalian counterparts. It discusses the role of macrophages in cellular immunity and some examples of genetic and environmental modulations of macrophage function. The chapter emphasizes chicken macrophage function because of limited research that has been conducted using macrophages of non-chicken avian species. While much of the information presented in this chapter concerns macrophages as effector cells, macrophages also serve as important regulatory cells of the immune system. In contrast, these cells could mobilize lymphocytes via the leukotrienes, process and present tumor-associated antigens (TAAs) to T lymphocytes, further activate lymphocytes with selected monokines, and, finally, directly kill the tumor cells via any combination of multiple pathways. A fourth pathway for macrophage cytotoxic action is a classic cytolytic process that involves enzymes broadly designated as cytolytic proteases.