CD26 EXPRESSION AND DIPEPTIDYL PEPTIDASE-IV ACTIVITY IN AN AGGRESSIVEHEPATOSPLENIC T-CELL LYMPHOMA

The transmembrane serine aminopeptidase dipeptidyl peptidase IV (DPP I V) (also known as CD26) participates in several immunological function s and has a binding affinity for several molecules, including collagen , which may be an integral mechanism for T cells to traverse endotheli al barriers, Since CD26 is phenotypically expressed in certain T-cell malignancies, this study utilized a novel four-color cytofluorographic procedure to measure DPP IV enzymatic activity concurrently with the expression of other surface markers in an aggressive hepatosplenic T-c ell lymphoma, Immunophenotypic analysis by flow cytometry revealed the tumor to be CD2+, CD3+, CD5-, CD7+, TcR-gamma delta+, CD4-, CD8+/-, C D56+, and CD11c+, The CD26 molecule was also expressed, and DPP IV act ivity was present, with the maximal activity detectable after IO min o f incubation, These results represent the initial description of enzym atically active CD26 in a T-cell malignancy, and raise the possibility that this molecule may be a participant in the pathogenetic mechanism s utilized by the neoplastic cells. (C) 1998 Wiley-Liss, Inc.