CD26 (DPIV, Dipeptidyl peptidase 4, EC=3.4.14.5, DPP IV, T-cell activation antigen CD26, TP103, Adenosine deaminase complexing protein 2, ADCP-2, ADABP, DPP4, ADCP2, CD26, Dipeptidyl Peptidase IV, Adenosine deaminase complexing protein 2, T cell activation anti)

CD26 (110 kDa) is a cell surface glycoprotein with known dipeptidyl peptidase IV activity in its extracellular domain which is present on various cell types, including T cells and epithelial cells of the liver, kidney, and intestine. CD26 has been identified as a key marker for monocytotropic HIV-1 infection, with a mechanism of early loss of CD26– expressing cells in HIV-1 infected individuals. CD26 is an indicator of T-cell activation and CD26 level has been shown to fluctuate in parallel with several autoimmune diseases such as rheumatoid arthritis and autoimmune thyroiditis.