The TY/11.8 monoclonal antibody specifically recognizes mouse CD73 which is also known as Ecto-5'-nucleotidase (5'-NT). CD73 is a ~69 kDa glycosylphosphatidylinositol (GPI)-anchored, cell-surface glycoprotein that is encoded by Nt5e which belongs to the 5'-nucleosidase family. CD73 expression appears to be developmentally regulated on leucocytes. In the bone marrow, it is found on most CD11b+ myeloid cells and very few CD19+ cells of the B-lymphocyte lineage. It is neither found expressed on CD11b+ cells in the periphery nor on bone marrow-derived GM-CSF-stimulated dendritic cells. Some peripheral B lymphocytes express CD73, with higher levels detected on Ig isotype-switched B cells. The few thymocytes which have detectable surface CD73 are found within CD4-CD8-and the CD4+CD8- subpopulations. In peripheral lymphoid organs, large proportions of the CD4+ and CD8+ T lymphocytes express CD73. Significant variation in the frequencies of peripheral CD73+ T cells have been observed amongst inbred mouse strains. For example, C57BL/6 mice reportedly have higher frequencies of peripheral CD73+ T cells when compared with BALB/c mice. In the thymus and peripheral lymphoid organs, CD73 is found on endothelial and stromal cells. CD73 has also been detected on bone marrow and thymic epithelial cell lines, kidney glomeruli and proximal-tubule epithelial cells, liver endothelial cells and hepatocytes, mesenchymal cells, and fibroblasts including cancer-associated fibroblasts (CAFs) found in tumors. CD73 has enzymatic and signal transduction activities. It catalyzes the dephosphorylation of extracellular nucleoside 5' monophosphates to nucleosides. CD73 acts on adenosine monophosphate (AMP) to generate and regulate the concentration of extracellular adenosine. Adenosine can bind to adenosine receptors expressed on cells in many tissues and regulate physiological responses including anti-inflammatory or immunosuppressive responses. Regulatory T cells (Treg) can generate immunosuppressive adenosine by their expression and activity of the CD39 and CD73 ectoenzymes.
