CD26 DIPEPTIDYL PEPTIDASE-IV EXPRESSION IN HUMAN LYMPHOMAS IS RESTRICTED TO CD30-POSITIVE ANAPLASTIC LARGE-CELL AND A SUBSET OF T-CELL NON-HODGKINS-LYMPHOMAS

CD26 is identical to the cell surface ectoenzyme dipeptidylpeptidase I V (DPPIV). CD26/DPPIV is associated with T-cell activation and prolife ration 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 lymphoma s, such as CD3O-positive anaplastic large cell (ALC) lymphomas and Hod gkin's disease (HD). A series of 81 lymphoma samples, including 23 cas es of HD, 17 cases of CD30-positive ALC lymphomas, 41 cases of other n on-Hodgkin's lymphomas (NHL), and a panel of HD- or ALC lymphoma-deriv ed human cell lines were evaluated for CD26/DPPIV expression by enzyme histochemistry and immunohistochemistry on frozen sections and cell s mears. CD26/DPPIV protein was expressed on neoplastic cells in 12 of 1 7 (71%) ALC lymphomas irrespective of their antigenic phenotype and in seven of 15 (47%) T-cell NHLs. In contrast, we did not detect CD26/DP PIV expression in tumor cells from 26 cases of B-cell NHL other than A LC lymphomas or in Reed Sternberg (RS) cells and variants of 21 of 23 HD cases. Accordingly, CD26/DPPIV expression was maintained on the CD3 0-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 sepa ration of ALC lymphomas from HD based on the differential expression o f the CD26/DPPIV molecule. Moreover, given the demonstration that CD26 /DPPIV is identical to the human adenosine deaminase (ADA) binding pro tein, it could be speculated that CD26/DPPIV also may function by inte racting with ADA to regulate the growth of CD26/DPPIV expressing neopl astic cells in ALC lymphomas. Copyright (C) 1994 by W.B. Saunders Comp any