This monoclonal antibody reacts with the mouse CD8â chain. The CD8â chain associates with the CD8á chain to form the CD8á/â heterodimer on MHC class I restricted T-cells (cytoxic T cells) and most thymocytes . Since a small subset of T cells (IEL cells) express CD8á/á homodimers rather than Cdá/â heterodimers, in- vestigators should use an antibody directed against the CD8á chain to definitively label mouse CD8 cells. This antibody is suitable for use in flow cytometry.