CD26/dipeptidyl peptidase IV expression in human lymphomas is restricted to CD30-positive anaplastic large cell and a subset of T-cell non-Hodgkin's lymphomas

Abstract

CD26 is identical to the cell surface ectoenzyme dipeptidyl peptidase IV (DPPIV). CD26 DPPIV is associated with T-cell activation and proliferation and also may function as an auxiliary adhesion factor. Although CD26 DPPIV has been previously studied on lymphoid populations and on leukemias/lymphomas of B- and T-cell phenotype, little is known about its expression and functional role in some specific types of lymphomas, such as CD30-positive anaplastic large cell (ALC) lymphomas and Hodgkin's disease (HD). A series of 81 lymphoma samples, including 23 cases of HD, 17 cases of CD30-positive ALC lymphomas, 41 cases of other non-Hodgkin's lymphomas (NHL), and a panel of HD- or ALC lymphoma-derived human cell lines were evaluated for CD26 DPPIV expression by enzyme histochemistry and immunohistochemistry on frozen sections and cell smears. CD26 DPPIV protein was expressed on neoplastic cells in 12 of 17 (71%) ALC lymphomas irrespective of their antigenic phenotype and in seven of 15 (47%) T-cell NHLs. In contrast, we did not detect CD26 DPPIV expression in tumor cells from 26 cases of B-cell NHL other than ALC lymphomas or in Reed Sternberg (RS) cells and variants of 21 of 23 HD cases. Accordingly, CD26 DPPIV expression was maintained on the CD30-positive ALC lymphoma cell line Karpas 299, but the molecule was not detected on HD-derived cell lines of B, T, or non-B non-T phenotype. These results may support a new potential tool for the phenotypic separation of ALC lymphomas from HD based on the differential expression of the CD26 DPPIV molecule. Moreover, given the demonstration that CD26 DPPIV is identical to the human adenosine deaminase (ADA) binding protein, it could be speculated that CD26 DPPIV also may function by interacting with ADA to regulate the growth of CD26 DPPIV expressing neoplastic cells in ALC lymphomas.