Cytochemical distribution of dipeptidylaminopeptidase IV (DAP IV; EC-3.4.14.5) in T-lymphoblastic lymphoma/leukemia characterized with monoclonal antibodies

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

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.

Possibilities and limitations of cytochemical methods in diagnosis of acute leukemia

Accurate identification and classification of leukemic blast cells is a very important prerequisite of the precise diagnosis of acute leukemia and has a great impact on therapy and prognosis. The purpose of this review is to consider, in the broad sense of the word, the present possibilities and limitations of enzyme cytochemistry and to emphasize how cytochemistry may contribute, on integration with the other methods of study, to the final classification and differential diagnosis of acute leukemia, a highly variable hematological disorder. In this review, the role of conventional enzyme cytochemistry, either dominant or subsidiary, in the discrimination of acute leukemia subtypes is discussed. The survey confirms the absolute necessity of immunologic marker analysis in the accurate diagnosis of acute lymphoblastic leukemia, undifferentiated or minimally differentiated leukemia and mixed-lineage leukemia because in these cases, the cytochemical evaluation provides insufficiently relevant information regarding blast cell origin, specificity of leukemia subtypes and the discrete stages of leukemic cell maturation. On the other hand, cytochemical investigation is appreciated to be dominant over immunophenotyping in characterizing acute myeloid leukemia, because of the lack of specificity of the majority of immunological markers against myeloid antigens and, because of the availability of standardized and sufficiently specific cytochemical reactions. The cytogenetic, molecular biological and electron microscopic studies mentioned in this review supplement the important information for correct differential diagnosis of acute leukemia. The prognostic impact of enzyme cytochemistry in correlation to other methods is evaluated.

Biosynthesis and metabolism of dipeptidylpeptidase IV in primary cultured rat hepatocytes and Morris hepatoma 7777 cells

N-Glycosylation, biosynthesis and degradation of dipeptidylpeptidase IV (EC 3.4.14.5) (DPP IV) were comparatively studied in primary cultured rat hepatocytes and Morris hepatoma 7777 cells (MH 7777 cells). DPP IV had a molecular mass of 105 kDa in rat hepatocytes and of 103 kDa in MH 7777 cells as assessed by SDS/PAGE under reducing conditions. This difference in molecular mass was caused by differences in covalently attached N-glycans. DPP IV from hepatoma cells contained a higher proportion of N-glycans of the oligomannosidic or hybrid type and therefore migrated at a slightly lower molecular mass. In both cell types DPP IV was initially synthesized as a 97-kDa precursor which was completely susceptible to digestion with endo-beta-N-acetylglucosaminidase H converting the molecular mass to 84 kDa. The precursor was processed to the mature forms of DPP IV, glycosylated with N-glycans mainly of the complex type with a half-life of 20-25 min. The transit of newly synthesized DPP IV to the cell surface displayed identical or very similar kinetics in both cell types with the major portion of DPP IV appearing at the cell surface after 60 min. DPP IV molecules were very slowly degraded in hepatocytes as well as in hepatoma cells with half-lives of approximately 45 h. Inhibition of oligosaccharide processing with 1-deoxymannojirimycin led to the formation of DPP IV molecules containing N-glycans of the oligomannosidic type. This glycosylation variant was degraded with the same half-life as complex-type glycosylated DPP IV. By contrast, inhibition of N-glycosylation with tunicamycin resulted into rapid degradation of non-N-glycosylated DPP IV molecules in both cell types. Non-N-glycosylated DPP IV could not be detected at the cell surface indicating an intracellular proteolytic process soon after biosynthesis.

Induction of antigen expression of follicular dendritic cells in a monoblastic cell line. A contribution to its cellular origin

Experiments were carried out to elucidate the cellular origin of the dendritic reticulum cell (DRC). The monoblastic cell line THP-1, the histiocytic cell line U-937, and the mononuclear cell fraction from peripheral blood (PMC) were stimulated with supernatants from lectin-stimulated peripheral blood lymphocytes and from stimulated T- and B-cell lines. Differentiation towards DRC was assessed by immunocytochemical demonstration of the DRC-specific antigen Ki-M4. Supernatants from isolated peripheral T lymphocytes and from T- and B-cell lines were capable of stimulating THP-1 to Ki-M4 antigen expression, whereas U-937 and the PMC fraction remained negative for this antigen throughout the experiments. These results provide further evidence for a relationship of DRCs with the mononuclear-phagocytic cell system and hence for their bone marrow origin. Furthermore, the data suggest that soluble factors of T and/or B cells are involved in mediating the differentiation process of precursor cells to DRC.

Biochemical properties of dipeptidyl peptidase IV in liver and hepatoma plasma membranes

In the present investigation we compared the glycoprotein DPP IV from rat liver and Morris hepatoma 7777 by means of biochemical and immunological methods. For that purpose nine monoclonal anti-DPP IV-antibodies recognizing four different epitopes and a monospecific anti-DPP IV-antiserum were applied. In the homogenates of both tissues a plasma membrane-bound and a soluble form were detected. The immunological cross-reactivity of both forms was demonstrated with the antiserum and the monoclonal antibodies against the epitopes A, B and C while epitope D was restricted to liver plasma membrane. Differences of the distinct DPP IV forms were exhibited in the molecular weights, isoelectric points and peptide maps. In the hepatoma homogenate only 10% of DPP IV activity was found compared to normal liver but the ratio of soluble to membrane-bound form is higher in the hepatoma than in the liver. The fractionation of the homogenates into different cell components revealed for the liver a continuous increase of DPP IV activity from the endoplasmic reticulum fractions to the Golgi apparatus and finally to the plasma membranes. By contrast, in hepatoma the flow from the Golgi apparatus to plasma membrane was greatly reduced. The loss of DPP IV from the surface of cultured hepatoma cells was concomitant with a decrease of cell-substratum adhesion. DPP IV was found to be inserted into the liver plasma membrane by two different mechanisms, a phospholipase C-sensitive and a papain-sensitive one. In the hepatoma the phospholipase C-sensitive anchorage was not expressed. Besides liver and hepatoma the distribution of DPP IV was characterized in various rat organs by enzyme activity, histochemistry and immunohistochemistry with the anti-DPP IV-antibodies.

Dipeptidyl peptidase (DPP) IV in rat organs. Comparison of immunohistochemistry and activity histochemistry

Immunohistochemistry and activity histochemistry were used to study the localization of dipeptidyl peptidase (DPP) IV in rats. For immunohistochemistry, polyclonal as well as monoclonal anti-DPP IV antibodies were employed. The pattern of DPP IV immunoreactivity, determined with polyclonal anti-DPP IV antibody, corresponds to the histochemical pattern found for the enzymic activity of DPP IV. Immunoreactivity was present, in addition, in nerve cells, lateral membranes of certain surface epithelia, e.g., Fallopian tube, uterus and vesicular gland, in the luminal cytoplasm of e.g., vesicular gland epithelium, and in mucous cells of Brunner's gland. The monoclonal antibodies against DPP IV recognized four different epitopes (A-D) of the DPP IV molecule, and revealed that certain epitopes were not detectable by immunohistochemistry in some organs. Generally, the staining intensities for epitopes A, B, C and D decreased in that order. Usually, the monoclonal antibodies against epitopes A and B showed similar reaction patterns to those as obtained with the polyclonal antibody. Epitope D was recognized in the lumen of the duct system of exocrine glands and the intestine. Furthermore, high reactivity of this epitope was detected in goblet cells of the intestine, where no DPP IV activity was present.

Histochemistry of dipeptidyl aminopeptidase (DAP) II and IV in reactive lymphoid tissues and malignant lymphoma

A modified histochemical method was used to show the presence of dipeptidyl aminopeptidase (DAP) II and IV in fixed, freeze dried, cryostat sections of tonsils, lymph nodes, and skin. In 14 reactive tonsils and lymph nodes both enzyme reactions were largely confined to T dependent areas where scattered positive lymphocytes were shown in the paracortical zones, while lymphocytes of germinal centres (B dependent areas) were negative. In either site some macrophages showed strong positivity for both enzymes. In 23 lymph node and two skin biopsy specimens of non-Hodgkin's lymphoma the neoplastic lymphocytes of 12 B cell lymphomas were completely unstained, whereas in the 13 cases of T cell lymphoma the neoplastic lymphocytes showed variable reactions with positivity for DAP II in eight and for DAP IV in seven, both reactions being positive in four and negative in two. Touch imprints of a lymph node from a case of Hodgkin's disease showed that the Reed-Sternberg cells were unreactive for both enzymes. The histochemistry of DAP II and IV may supplement other histochemical and immunological markers in the cytological classification of lymphomas.

T-cell lymphomas of the stomach: morphological and immunological studies characterizing two cases of T-cell lymphoma

Using cytochemical, electron microscopic and immunohistochemical techniques in 20 primary malignant lymphomas of the stomach, we found 18 B-cell and 2 T-cell lymphomas. Primary T-cell lymphoma in the stomach has not been previously reported. The T cells in both cases were reminiscent of T immunoblasts with prominent nucleoli and a basophilic cytoplasm. Case 1 showed a cytological relationship to pleomorphic T-cell lymphoma, large cell type. Case 2 contained in addition some cells not previously described in T-cell lymphomas, resembling immature plasma cells with abundant rough endoplasmic reticulum. Focal positivity to acid phosphatase and dipeptidylaminopeptidase IV suggests the T-cell nature of both lymphomas. In both cases the tumour cells were OKT 11 and OKT 4 positive, and negative for OKT 8. Thus, both cases represent high-grade malignant T-cell lymphomas which correspond phenotypically to T-helper cell lymphoma. Case 2 revealed a further immunohistochemical peculiarity: atypical immunoblasts reacted positively with Ki-1 antibody. Thus, it is a Ki-1 lymphoma of T-cell type.

Comparative cytochemical study of dipeptidyl aminopeptidase (DAP) II and IV in normal and malignant haemic cells

Modified cytochemical methods were used to show dipeptidyl aminopeptidases (DAP) II and IV in peripheral blood buffy coat preparations and bone marrow smears. In 23 normal buffy coats both enzymes were confined to lymphocytes. DAP II was found in T and B lymphocytes (about 80%) while DAP IV was restricted to T lymphocytes only (around 46%). In 11 normal bone marrows DAP II was found in 53% of the lymphocytes, as well as in plasma cells, macrophages, and occasional myeloblasts. DAP IV was found only in lymphocytes (around 32%). DAP II activity, but not DAP IV activity, was present in all of the mast cells in a case of systemic mastocytosis. Whereas DAP II was found, to a variable extent, in leukaemic myeloblasts, monoblasts, proerythroblasts, and in megakaryoblasts in 52 cases of acute myeloid leukaemia, DAP IV was not shown. Variable positivity to DAP II and DAP IV was found in the lymphoblasts in seven cases of acute lymphoblastic leukaemia, in 14 cases of B chronic lymphocytic leukaemia, and in three cases of non-Hodgkin's lymphoma. DAP II activity was variable compared with DAP IV activity, which was constantly reduced. Virtually all of the myeloma cells (96%) all of the myeloma cells (96%) in five cases of multiple myeloma and two cases of plasma cell leukaemia were DAP II positive and DAP IV negative. In 10 cases of hairy cell leukaemia most hairy cells were positive to DAP II (74%) with no demonstrable DAP IV activity. In a single case of Sézary's syndrome around 90% of the helper T cells were positive to DAP II with no DAP IV activity.

A monoclonal antibody detecting dipeptidylpeptidase IV in human tissue

Dipeptidylpeptidase IV (DPP IV) occurs among others in exocrine epithelia, hepatocytes, renal tubuli, endothelia, and myofibroblasts of man and laboratory animals. Also T mu lymphocytes and their varying differentiated neoplastic counterparts reveal this enzyme activity. The present paper describes a new monoclonal antibody recognizing DPP IV. Additional efforts have been taken to detect the subcellular localization of DPP IV and its isoelectric focusing pattern in different tissue types. The monoclonal antibody anti-DPP IV (clone II-19) shows a reaction pattern indistinguishable from the corresponding enzymehistochemical reaction. These findings were further substantiated by immunoblotting analysis. In line with the results of direct enzyme measurements in different subcellular fractions a considerable portion of the enzyme is localized in the membrane fraction.