Human CD199, also known as CCR9, is a member of the G protein coupled receptor family and is involved in T cell development in the thymus and in the gut-associated immune response. It is highly expressed on different stages of thymocytes and upregulated on CD4⁺ CD8⁺ cells. Expression of CCR9 on γ/δ T cells in the intraepithelial and small intestine has been reported. The interaction of CCR9 with its ligand CCL25 (TECK, thymus-expressed chemokine) may direct the trafficking of developing T cells in the thymus and the generation of gut-specific immunological memory.

Each lot of this antibody is quality control tested by immunofluorescent staining with flow cytometric analysis. For flow cytometric staining, the suggested use of this reagent is ≤1.0 microg per million cells in 100 microL volume. It is recommended that the reagent be titrated for optimal performance for each application.