Immunophenotyping Pig Immune Cells by Flow Cytometry: A Powerful Tool for Pharmacology and Toxicology Studies

Authors: Darcey L. Clark, Lynette Brown, and Jennifer J. Stewart
Flow Contract Site Laboratory, 18323 Bothell Everett Hwy, Suite 110, Bothell, WA 98012

Abstract: Pigs are increasingly used in biomedical research because they share many physiological and anatomical similarities to human. Although dogs and non-human primates have traditionally been used for this purpose, ethical concerns have increased the demand for alternatives (Swindle 2012). Because the pig has been a focus of vaccine research for many years, pig-specific immunology reagents exist as research tools. Pigs have some unique aspects to their immunology: in general pigs have higher circulating leukocytes, a lower ratio of CD4:CD8 T cells, and express more double positive (DP) CD4+/CD8+ cells than other species. These DP cells increase with age and after vaccine and/or infection, and are thought to have memory phenotype. Pigs also have a higher percentage of γδ T cells than other species. γδ T cells are highest in younger animals, express SLA-DR (Swine Leukocyte Antigen, MHC II), and CD8, and are thought to have cytolytic activity and memory. Unlike other species, SLA-DR is preferentially expressed on CD8+ T cells and is up- regulated on activated cells.