Recognizes a glycoprotein of 110kDa, identified as CD26 (Workshop VI; Code: N-L039). It is an atypical serine protease belonging to the prolyl oligopeptidase family. It is expressed on lymphocyte cells and is upregulated during T-cell activation. CD26 is also expressed on activated B cells and natural killer cells and abundantly on epithelia. CD26 is implicated in a variety of biological functions including T-cell activation, cell adhesion with extracellular matrix such as fibronectin or collagens, and in HIV infection. Cross-linking of CD26 using this antibody dramatically enhances the anti-CD3-induced IL-2 production. In Western blotting, this MAb reacts with only glycosylated CD26, but not with the deglycosylated form. It does not prevent ADA binding to CD26.