Description:
In the chicken, the CD8 molecule is present in two forms - (i) a homodimer of two α chains and (ii) a heterodimer of an α chain and a β chain. Chicken CD8 is expressed on approximately 80% of thymocytes, 45% of blood mononuclear cells, and 50% of spleen cells but less than 1% of cells in the bursa and bone marrow. While the vast majority of CD8+ cells in the thymus, spleen, and blood of adult chickens express both CD8α- and CD8β-chains, a relatively large proportion of the CD8+ TCRγδ cells in the spleens of embryos and young chicks express only the α-chain of CD8. Among intestinal epithelial lymphocytes, the major CD8+ T cell populations present in mice are conserved but there is a population of TCRγδ CD8αβ cells in the chicken that is not found in rodents. The monoclonal antibody 3-298 recognizes the CD8α chain of both the chicken and turkey.