Hairy Cell Leukemia: Enzyme-histochemical and Ultrastructural Investigation of one Case

The investigation was carried out on blood smears, bone marrow aspirates, one lymph node biopsy, and the surgically removed spleen of a 53-year-old man with hairy cell leukemia. In the blood smears stained with May-Grünwald-Giemsa, 60 to 70 % of the hairy cells contained tubular inclusions that corresponded to the ribosome-lamella complexes demonstrated at electron microscopy. In blood smears, imprints and cryostatic sections of the lymph node and of the spleen, hairy cells revealed tartrate-resistant acid phosphatase, beta-glucuronidase and adenosine-triphosphatase activity. In the spleen neutral esterase and alkaline phosphatase demonstrated the numerical increase of the histiocytes, which ultrastructurally displayed phagocytic activity. The presence in the spleen of pseudosinuses lined by hairy cells was confirmed by electron microscopy as well as by cytoenzymology.

Central role of protein kinase Cepsilon in constitutive activation of ERK1/2 and Rac1 in the malignant cells of hairy cell leukemia

We have previously identified the presence of Ras/Raf-independent constitutive activation of extracellular signal-regulated kinase (ERK) in the hairy cells (HCs) of hairy cell leukemia. The aim of the present study was to characterize the signaling components involved in this activation and their relationship to the reported activation of Rac1. We found that both Rac1 and ERK activation in HCs are downstream of active Src and protein kinase C (PKC). Inhibition with toxin B showed that Rac1 plays no role in ERK activation in HCs. However, toxin B inhibited p60src and the Rac1-GEF Vav, demonstrating a positive feedback/activation of p60src by Rac1. Treatment with specific small interfering RNA for various PKC isoforms, or with PKC isoform-specific inhibitors, demonstrated a central role for PKCepsilon in the constitutive activation of Rac1 and ERK in HCs. PKCepsilon and active ERK were mutually associated and co-localized with mitochondria in HCs. Furthermore, active PKCepsilon was nitrated on tyrosine, pointing to a reactive oxygen species-dependent mechanism of activation. By being involved in activation of ERK and Rac1, PKCepsilon plays roles in both the survival of HCs and in the cytoskeletal dynamics responsible for the distinctive morphology and tissue homing of these cells. Our study therefore describes novel aspects of signaling important for the pathogenesis of hairy cell leukemia.

Purine analogues: rationale for development, mechanisms of action, and pharmacokinetics in hairy cell leukemia

Cladribine is effective therapy for HCL, and there are several ways to achieve the adequate concentrations of the active metabolites in relevant cells, without the need for long-term continuous infusions. This simplifies therapy, although careful control of patients is required during and after treatment in most instances because of the significant activity of the drug on leukemia cells of various types and also on lymphoid cells and normal stem cells.

The value of tartrate resistant acid phosphatase (TRAP) immunoreactivity in diagnosis of hairy cell leukemia

Hairy cell leukemia (HCL) is a rare chronic B-cell lymphoproliferative disorder characterized by splenomegaly, pancytopenia, and circulating atypical lymphocytes with circumferential cytoplasmic projections. We investigated the specificity and the sensitivity of anti-TRAP antibody immunoreactivity in 57 cases of HCL. We found that there is a statistically highly significant difference between TRAP immunoreactivities of the study and the control groups, and HCL can be diagnosed by TRAP immunoreactivity in bone marrow trephine biopsy materials with a specificity of 98.27 % and a sensitivity of 100%.

Disruption of a novel ectodermal neural cortex 1 antisense gene, ENC-1AS and identification of ENC-1 overexpression in hairy cell leukemia

Karyotypical alteration of chromosome 5 and in particular band 5q13 is a frequent finding in hairy cell leukemia (HCL). We have previously identified a number of candidate genes localized in close proximity to a constitutional inv(5)(p13.1q13.3) breakpoint in one HCL patient. These included beta-hexosaminodase HEXB, frequently mutated in the lysosomal storage disorder Sandhoff disease. We now report that the 5q13.3 breakpoint disrupts a novel evolutionary conserved alternative isoform of HEXB. This isoform directly overlaps, in a cis-antisense fashion, exon 1 of the gene for ectodermal neuronal cortex 1 ENC-1, and was thus named ENC-1AS. ENC-1 has previously been shown to be overexpressed in several malignancies, and is believed to play a critical regulatory role in malignant transformation of various tumors. Importantly, subsequent analysis of ENC-1 in purified primary HCL tumor cells revealed a striking upregulation of ENC-1 in all 26 patients examined, compared with normal peripheral blood lymphocytes from healthy donors. Upon further analysis of the ENC-1/ENC-1AS locus, we identified a complex 5' regulatory mechanism involving an inverse expression of the ENC-1 sense and the ENC-1AS transcripts in several tissues supporting the hypothesis that expression of ENC-1AS regulates ENC-1 levels. In addition, we have also found tissue-specific methylation of a 1.2 kb segment encompassing the overlapping ENC-1/ENC-1AS 5' exons, adding to the complexity of the regulation of this locus. Altogether, these results suggest that upregulation of ENC-1 contributes to the development of HCL and provides new information on the possible dysregulation of ENC-1 including expression of a novel antisense gene, ENC-1AS.

Regulation of hairy-cell survival through constitutive activation of mitogen-activated protein kinase pathways

The hairy cells (HCs) of hairy-cell leukemia are intrinsically activated mature clonal B cells. The aims of this study were to gain further insights into the nature of this activation and to assess its importance for the prolonged HC survival in this chronic disease. We show that HCs contain phosphorylated/activated p38 MAPK, JNK and ERK1/ERK2 (ERK1/2). PKC inhibitors increased the activation of p38 and JNK, but reduced the phosphorylation of ERK1/2. Moreover, PKC inhibition resulted in cell death; cell death was also observed when the activation of ERK1/2 in HCs was abrogated with an inhibitor of MEK1/2 activation. In addition to PKC, active Src kinase was also shown to be involved in the maintenance of Raf-independent ERK activation in HCs. During cell culture on a nonadherent surface, ERK phosphorylation was sustained, while phosphorylation of p38 and JNK decreased. This decrease was not observed in HCs cultured on vitronectin (VN), indicating that p38/JNK activation is probably a consequence of in vivo HC interaction with VN present in abundance in the red pulp of the spleen. Taken together, these results suggest that active p38/JNK make HCs susceptible to apoptosis, but the cells are effectively rescued by ERK activation involving constitutively active PKC and Src. These findings are relevant for the understanding of the prolonged cell survival of HCs and their selective sensitivity to some chemotherapeutic agents.

Expression of a functional inducible nitric oxide synthase in hairy cell leukaemia and ESKOL cell line

The expression of nitric oxide synthase (NOS) isoforms was investigated in the established ESKOL hairy cell line and in leukemic cells of patients with hairy cell leukemia (HCL). By reverse transcription-polymerase chain reaction (RT-PCR), these cells were found to spontaneously express inducible NOS (iNOS)-specific mRNA, but not endothelial constitutive NOS (ecNOS) mRNA. The iNOS protein was detected by immunofluorescence in the cytoplasm of permeabilized leukemic cells and ESKOL cells, using different anti-iNOS monoclonal antibodies. A protein of 135 kDa was identified by Western blotting in ESKOL and HCL lysates, confirming the presence of an iNOS in these cells. Cytosolic homogenates displayed NOS catalytic activity, as measured by the conversion of 14C-labelled L-arginine into 14C L-citrulline and by detection in situ using the DAF-2DA (diaminofluorescein diacetate) NO-sensitive fluorescent probe. Ligation of CD23 (low affinity IgE receptor) was found to increase iNOS expression in ESKOL and conversely to decrease the percentage of cells undergoing apoptosis, as measured by the percentage of cells expressing annexin V. These results indicate that, as in chronic B cell lymphocytic leukemia cells (B-CLL) a functional iNOS is expressed constitutively in hairy cells that contributes to protecting these tumoral cells from apoptosis.

Telomerase activity in chronic lymphoproliferative disorders of B-cell lineage

The progressive shortening of telomeres at each cell division is a key mechanism in controlling cell proliferative capacity. The activation of telomerase, a reverse transcriptase that extends telomere length, potentially leads to unlimited cell proliferation, and is believed to play a critical role in the neoplastic process. High levels of telomerase activity have been demonstrated in almost all solid tumours; however, little data is available concerning its expression in chronic B-cell neoplasms. By using a quantitative polymerase chain reaction-based method we quantified telomerase activity in normal B lymphocytes, and in various B-cell malignancies, including chronic lymphocytic leukaemia (CLL), mantle cell lymphoma (MCL) and hairy cell leukaemia (HCL). Compared to normal B cells, which expressed very low levels of telomerase activity, malignant cells from most of the patients showed a significant increase in telomerase activity, with highest values observed in HCL samples. Moreover, among the CLL and HCL cases, significantly higher levels of telomerase activity were found in patients with progressive disease at 1 year follow-up versus patients with stable disease. These data suggest that telomerase activity might correlate with disease progression.

Species specificity of monoclonal antibodies to human tartrate-resistant acid phosphatase

Tartrate-resistant acid phosphatase (TRAP) is expressed abundantly by osteoclasts and is required for bone resorption. This enzyme is emerging as an important biomarker in bone pathology, both for histochemical identification of osteoclasts and as a serum marker of osteoclast activity and increased bone turnover. Rat and mouse models are becoming popular systems for studying osteoclast development, bone physiology and morphogenesis, and bone diseases such as osteoporosis. We have developed two unique antibodies to human TRAP purified from hairy cell leukemia spleen. Both antibodies (9C5 and 14G6) are suitable for immunohistochemistry of osteoclasts and macrophages. Only one (14G6) is capable of immunoprecipitating active TRAP from human cell lysates. Antibody 9C5 reacts with a denatured epitope of TRAP while antibody 14G6 probably reacts with a native, conformational determinant. The high degree of homology among TRAPs of various species predicts that these antibodies should be suitable for work in experimental animals as well as humans. Immunohistochemical staining, electrophoretic analyses, immunoprecipitation and immunoblotting assays of human rat and mouse TRAP were carried out to test the validity of these antibodies as cell markers in rodents. Both antibodies were suitable for immunohistochemistry in all species. Antibody 9C5 was suitable for immunoblotting of denatured TRAP of all species tested. Antibody 14G6 reacted with the native TRAP of humans only and failed to immunoprecipitate mouse or rat TRAP activity. Although TRAP is a phylogenetically conserved protein, subtle, species-specific determinants exist. Care should be exercised when anti-TRAP antibodies are used for immunoassay in experimental animals.

Immunohistochemical demonstration of acid phosphatase isoenzyme 5 (tartrate-resistant) in paraffin sections of hairy cell leukemia and other hematologic disorders

The demonstration of tartrate-resistant acid phosphatase (TRAP) activity has long been a cornerstone in the diagnosis of hairy cell leukemia (HCL). Recently a monoclonal antibody to this enzyme has been developed that can be used in an immunoperoxidase method on paraffin-embedded tissues. By using a peroxidase-labeled streptavidin biotin method, paraffin sections of B5 and formalin-fixed tissue from 86 cases of HCL (41 bone marrow, 36 spleen, 9 liver) were stained with the antibody to TRAP and compared against staining for CD20 (L26) and DBA.44 (DAKO, Carpinteria, Calif). In addition, 193 specimens (127 bone marrow, 42 lymph node, 19 spleen, 5 other) from a variety of neoplastic and nonneoplastic hematologic conditions were stained using the monoclonal antibody to TRAP. For comparison, these cases were also stained with DBA.44. In the cases of HCL, 80 of 86 specimens were immunoreactive for TRAP. While the antibody to TRAP generally stained less than 50% of the hairy cells, CD20 and DBA.44 stained 90% and 50% to 60% of hairy cells, respectively. Two of three cases of marginal zone lymphoma showed weak immunoreactivity to the TRAP antibody. Two specimens from a patient with Gaucher's disease and 8 of 13 cases of mastocytosis also showed positivity to the TRAP antibody in the macrophages and mast cells, respectively. In contrast, staining for DBA.44 was positive in 3 of 9 cases of B-cell large cell lymphoma, 1 of 4 cases of mantle cell lymphoma, and in the paraimmunoblasts of 1 of 7 cases of small lymphocytic lymphoma. Only HCL was TRAP and DBA.44 positive. This antibody to TRAP is a useful addition to the diagnosis of HCL but should be used in conjunction with CD20 and DBA.44. The use of this antibody to determine minimal residual disease after chemotherapy was not addressed.

Characterization of monoclonal antibodies specific to human tartrate-resistant acid phosphatase

A major product of osteoclasts, tartrate-resistant acid phosphatase (TRAP) is an essential but insufficient enzyme for bone resorption. TRAP is an excellent cell marker for osteoclasts and macrophages and is being investigated as a serum marker for osteoclast activity in diseases of bone destruction. For decades, TRAP has also been used as a marker for hairy cell leukemia. Immunoassays for TRAP are sought to increase the sensitivity and specificity of the TRAP test for bone and hairy cells. Our laboratory recently developed a monoclonal antibody to TRAP (9C5) useful for immunohistochemical identification of TRAP-positive cells in paraffin sections. Herein, we characterize 9C5 in greater detail and report production of another anti-TRAP monoclonal antibody antibody (14G6) reactive with native, active enzyme antigen. Enzyme immunoassay, immunoprecipitation, western blot, and immunohistochemical analyses revealed the contrasting properties of 9C5 and 14G6. Antibody 9C5 reacts with a heat-denatured epitope and is suitable for denaturing western blot analysis and for immunohistochemistry. Antibody 14G6 reacts with a conformational determinant destroyed by heat and is suitable for immunoprecipitation of active TRAP, although 20% to 30% of activity is inhibited in the immune complexes. Having characterized several properties of these anti-TRAP antibodies, 9C5 and 14G6 may be useful for development of TRAP-specific immunoassays in bone pathology and hematology. They will certainly be of use for the study of biosynthesis, regulation, expression, and function of TRAP.

Epitope enhancement for immunohistochemical demonstration of tartrate-resistant acid phosphatase

We have developed a monoclonal antibody (9C5) for immunohistochemical localization of tartrate-resistant acid phosphatase (TRAcP). This antibody reacts with a denatured epitope of TRAcP and requires enhancement methods to promote antigenicity in paraffin-embedded tissues. We used this antibody to systematically examine proteolytic digestion and heat denaturation conditions for epitope enhancement in both paraffin sections and fixed smears. The goal was to increase the sensitivity of the immunohistochemical stain for TRAcP. Optimal conditions for proteolytic digestion were established. Denaturation in a conventional boiling water bath was compared to microwave irradiation in several commonly used solutions. Immunohistochemistry was compared directly to TRAcP cytochemistry in fixed smears from hairy cell leukemia specimens to gauge the level of sensitivity of our improved method. Attempts were made to "retrieve" the 9C5 epitope from overfixed tissues and aged smears. Maximal immunoreactivity of TRAcP was achieved by microwave irradiation in a citrate or Tris buffer of pH 6.0-8.0 without the need for a subsequent protease digestion step. With this method of epitope enhancement, immunohistochemistry with antibody 9C5 was as sensitive as direct cytochemical staining of TRAcP activity. However, once a tissue specimen had been overfixed or a smear stored for a year or more, the 9C5 epitope was no longer retrievable. The key element in epitope enhancement for 9C5 immunohistochemistry is heat denaturation of the target epitope. Immunohistochemistry of TRAcP in paraffin sections would be a great asset to the study of specialized forms of the monocyte/macrophage lineage and to the process of macrophage activation. It would also provide another means for more precise evaluation of residual disease in bone marrow of patients treated for hairy cell leukemia.

Immunohistochemical detection of tartrate-resistant acid phosphatase in non-hematopoietic human tissues

Immunohistochemical studies were done on formalin-fixed, paraffin-embedded tissues to evaluate the specificity of a newly developed monoclonal antibody (9C5) against tartrate-resistant acid phosphatase. Sections from 195 specimens were examined, which included 33 types of tissues/organs. These tissues included normal, inflammatory, and neoplastic processes. Neoplastic tissues from 14 patients with hairy cell leukemia served as positive controls. Epitope enhancement was accomplished either by microwave irradiation in citrate buffer or by boiling in water followed by trypsin digestion. Tissues were reacted with monoclonal antibody 9C5 and stained with either the avidin-biotin peroxidase method or the alkaline phosphatase anti-alkaline phosphatase method. The hairy cells of all cases of hairy cell leukemia reacted positively with 9C5. Other positively stained cells included osteoclasts, activated macrophages and giant cells. Immunohistochemical studies with 9C5, when interpreted within the context of the specificity of this antibody, are useful for the diagnosis and assessment of treatment results for hairy cell leukemia. Monoclonal antibody 9C5 also may be useful as a marker for osteoclasts and the activated macrophages and for the diagnosis of disorders involved by these cells.

Hairy cell identification by immunohistochemistry of tartrate-resistant acid phosphatase

Tartrate-resistant acid phosphatase (TRAcP) has been an indispensible marker for hairy cell leukemia (HCL) for over two decades. However, the traditional TRAcP cytochemical stain cannot be performed effectively on sections of paraffin-embedded tissues that are important resources for histopathologic evaluation in diagnosis and treatment of HCL. Wide variation in expression of TRAcP activity by hairy cells (HCs) within and among patients is an interesting biologic phenomenon that has not been explained and can cause some diagnostic uncertainty as well. To solve the problem of staining TRAcP in paraffin sections and to begin to address the questions of variable TRAcP expression in HCL, we developed a monoclonal antibody to TRAcP, 9C5, for immunohistochemical identification of HCs. In smears of blood and bone marrow, immunocytochemistry of TRAcP using 9C5 was as specific but slightly less sensitive than direct cytochemical staining of enzymatic activity. In paraffin sections of spleen and bone marrow from HCL patients, immunohistochemistry with 9C5 stained the HCs with high sensitivity and specificity and clearly showed the characteristic diffuse infiltration by HCs. Other cells noted to stain strongly with 9C5 were occasional macrophages in bone marrow smears and osteoclasts and occasional tissue macrophages in paraffin sections. These are cells known to express abundant TRAcP activity. Immunohistochemistry with anti-TRAcP monoclonal antibody 9C5 may have utility as an added option in the diagnosis of HCL, as a means to evaluate residual disease in HCL patients undergoing new treatments, and as a way to address questions regarding variable expression of TRAcP activity by HCs within and among patients with HCL. Also, 9C5 has potential as a reagent for the immunoassay of bone-derived serum TRAcP in patients with certain bone diseases and cancers with bone metastasis.

Expression of deoxycytidine kinase and phosphorylation of 2-chlorodeoxyadenosine in human normal and tumour cells and tissues

Deoxycytidine kinase (dCK) activates several clinically important drugs, including the recently developed antileukaemic compound 2-chlorodeoxyadenosine (CdA). The distribution of dCK in cells and tissues has previously been determined by activity measurements, which may be unreliable because of the presence of other enzymes with overlapping substrate specificities. Therefore we have measured dCK polypeptide levels in extracts of normal and malignant human peripheral blood mononuclear cells, gastrointestinal tissues and sarcomas, using a specific immunoblotting technique, as well as the phosphorylation of CdA in the same extracts. High levels of dCK were found in all major subpopulations of normal mononuclear leucocytes (120 +/- 19 ng dCK/mg protein) and in B-cell chronic lymphocytic leukaemia (81 +/- 30 ng/mg, n = 23). Hairy-cell leukaemia contained lower levels (28 +/- 23 ng/mg, n = 7), as did three samples of T-cell chronic lymphocytic leukaemia (18 +/- 14 ng/mg). Phytohaemagglutinin stimulation of normal lymphocytes did not lead to any substantial increase in either dCK activity or protein expression (less than 2.5-fold). The human CEM wt T-lymphoblastoid cell line contained 56 +/- 1 ng/dCK/mg protein, while in the CEM ddC50 and AraC8D mutants that lack dCK activity, no dCK polypeptide could be detected. In colon adenocarcinomas, the dCK content was significantly higher (20 +/- 9 ng/mg, n = 20) than in normal colon mucosa (8 +/- 3.5 ng/mg, n = 19, P < 0.05). A similar pattern of dCK expression was found in gastric adenocarcinomas (21 +/- 13 ng/mg, n = 5) and normal stomach mucosa (6 +/- 5 ng/mg, n = 5, P < 0.15). One leiomyosarcoma and one extra-skeletal osteosarcoma showed dCK levels comparable with those found in normal lymphocytes (84 +/- 6 and 109 +/- 4 ng/mg, respectively), while other sarcoma samples contained lower levels, comparable to the gastrointestinal adenocarcinomas (20 +/- 7 ng/mg, n = 12). Thus, dCK is expressed constitutively and predominantly in lymphoid cells, but it is also found in solid non-lymphoid tissues, with increased levels in malignant cells. The phosphorylation of CdA in crude extracts showed a close correlation to the dCK polypeptide level.

Properties and levels of deoxynucleoside kinases in normal and tumor cells; implications for chemotherapy

Deoxynucleoside kinases are key enzymes in deoxyribonucleoside salvage, activating several clinically important chemotherapeutic drugs. The four known kinases, cytosolic thymidine kinase (TK1) and deoxycytidine kinase (dCK) and the mitochondrial thymidine kinase (TK2) and deoxyguanosine kinase (dGK), have been purified and characterized as to the subunit structure as well as specificity with a large number of analogs. These results are summarized and used to establish selective assays for the four enzymes in crude extracts of normal and malignant human peripheral blood mononuclear cells, gastrointestinal tissues and sarcomas. TK2 and dGK activities were found at low levels in all tissues, possibly correlated to the content of mitochondria. TK1 activity was detected only in samples containing a significant number of S phase cells. We have measured dCK activity as well as dCK polypeptide level by immuno blotting in these extracts. High levels of dCK were found in normal mononuclear leukocytes (91-145 ng dCK/mg protein) and in B-cell chronic lymphocytic leukemia (80 +/- 30 ng/mg, n = 23). Hairy cell leukemia contained lower levels (28 +/- 23 ng/mg, n = 7), as did unexpectedly three samples of T-cell chronic lymphocytic leukemia (18 +/- 14 ng/mg). Phytohemaglutinine stimulation of normal lymphocytes did not lead to any substantial increase in either dCK activity or expression (less than 2.5-fold). In colon adenocarcinomas, the dCK content was significantly higher (21 +/- 9.3 ng/mg, n = 20) than in normal colon mucosa (8.2 +/- 3.7 ng/mg, n = 19, p < 0.05). A similar pattern of dCK expression was found in gastric adenocarcinomas (21 +/- 13 ng/mg, n = 5) and normal ventricular mucosa (6.2 +/- 5.4 ng/mg, n = 5, p < 0.15). One leiomyosarcoma and one extra-skeletal osteosarcoma showed a dCK levels comparable to those found in normal lymphocytes (84 +/- 6 and 109 +/- 4 ng/mg), while other sarcoma samples contained levels comparable to the gastrointestinal adenocarcinomas (20 +/- 7 ng/mg, n = 12). We confirm that dCK is expressed constitutively and predominantly in lymphoid cells, but conclude that a significant expression may be found in non-lymphoid tissues as well, with increased levels in the corresponding tumor tissue. 2-Chlorodeoxyadenosine (CdA), an antileukemic agent used in treatment of hairy cell leukemia and chronic lymphocytic leukemias (B-CLL), is phosphorylated by dCK which was used as the selective substrate for this enzyme. A study was performed to investigate if there was a correlation between the dCK levels and the response to CdA treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Predominance of a distinct subtype of hairy cell leukemia in Japan

Forty Japanese patients with hairy cell leukemia (HCL) were reviewed. Nine cases were diagnosed as typical HCL, and two cases had the features of HCL variant (prolymphocytic variant). The remaining 29 cases (72.5%) differed morphologically and hematologically from the other two groups in that they usually had a moderately high leukocyte count (average 27.9 x 10(3)/microliters), and abnormal cells showing a densely stained round nucleus and an inconspicuous nucleolus. Tartrate-resistant acid phosphatase reaction was weak, and their cells exhibited generally smooth or slightly irregular, cellular outlines in smears. The cells showed weak expression of surface immunoglobulin G (IgG) with kappa-chain predominance. CD25 antigen was not detected. Some of these findings resemble those of B-cell chronic lymphocytic leukemia, but the patients also had several important features of HCL. They had splenomegaly without significant lymphadenopathy. The abnormal cells were CD20+, CD11c+ and showed typical 'hairy morphology' under phase-contrast and scanning electron microscopy. Furthermore, spleen sections revealed diffuse infiltration by the abnormal cells in the red pulp. From these findings, we speculated that this group of patients constitute a distinct subtype of HCL which is commonly seen in Japan. We propose to term the disease as HCL Japanese variant.

Relationship of deoxycytidine kinase and cytoplasmic 5'-nucleotidase to the chemotherapeutic efficacy of 2-chlorodeoxyadenosine

The agent 2-chlorodeoxyadenosine (2-CdA) has chemotherapeutic activity in hairy cell leukemia (HCL) and in refractory chronic lymphocytic leukemia (CLL). The cytotoxic activity of 2-CdA requires the intracellular accumulation of 2-CdA nucleotides. Deoxycytidine kinase (dCK) and cytoplasmic 5'-nucleotidase (5'-NT) are the principal enzymes that phosphorylate 2-CdA and dephosphorylate 2-CdA 5'-monophosphate, respectively. The net accumulation of 2-CdA nucleotides may therefore depend on both dCK and 5'-NT. The purpose of the present experiments was to determine if there is a relationship between pretreatment levels of dCK and 5'-NT in HCL and in CLL cells, and the clinical outcome of 2-CdA treatment. As measured by a direct immunoassay for dCK in 25 CLL patients, and by a 5'-NT activity assay in 23 patients, mean dCK levels were significantly higher in 2-CdA responders than in nonresponders (P < .01), whereas mean 5'-NT levels were significantly lower in 2-CdA responders than in nonresponders (P < .05). Mean dCK levels were higher in six HCL 2-CdA responders than in one nonresponder, whereas mean 5'-NT levels were lower in the 2-CdA responders than in the nonresponder. These results suggest that both dCK and 5'-NT are determinants of 2-CdA responsiveness.

Heterogeneity of hairy cell tartrate-resistant acid phosphatase

The human nonerythrocytic acid phosphatases (AcP) are composed of seven distinct activity bands in nondenaturing polyacrylamide gel electrophoresis (PAGE) when stained using either 1-naphthyl phosphate or naphthol ASBI phosphate as substrate. They are numbered 0, 1, 2, 3, 3b, 4, and 5 according to their increasing mobility toward the cathode in acidic conditions. Of these, only the most cationic "band 5" is tartrate resistant (TRAcP). When naphthol ASBI phosphate is used as substrate, AcP activity can also be stained in situ. In the presence of tartrate, activity remains strong in the hairy cells (HC) of hairy cell leukemia (HCL). Thus, the TRAcP stain has remained a reliable marker for HC. To investigate the function of TRAcP in HC, we purified two isoforms of TRAcP from HCL spleen tissue and found them to have similar substrate specificities and inhibitor sensitivities. In this report, we describe in detail the methods for TRAcP purification and compare some of the structural properties of the two isoforms to reinforce the concept that human TRAcP is a heterogeneous group of related enzymes. Band 5 represented only 15-20% of the total TRAcP extracted from HCL spleen. The remaining 80% of TRAcP hydrolyzed p-nitrophenyl phosphate but not naphthol ASBI phosphate and was not detectable in acidic, nondenaturing PAGE gels. Band 5 was solubilized from tissue using 500 mmol/L NaCl after previous extraction with 0.5% (v/v) NP-40 removed most other AcP and TRAcP activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative immunoassay of human deoxycytidine kinase in malignant cells

Deoxycytidine kinase (dCK) is necessary for the activity of several nucleosides used for the chemotherapy of cancer and AIDS. However, the measurement of dCK catalytic activity in crude cell extracts may be imprecise, due to the presence of phosphatases and nucleotidases that degrade the enzyme products. We describe a simple immunoassay for dCK that can measure accurately as little as 5 ng enzyme protein in crude tissue extracts. The assay enabled us to show (i) that mutant cells deficient in dCK activity lack immunoreactive dCK protein, (ii) that dCK catalytic activity and immunoreactivity correlate closely in human tumors, and (iii) that immunoreactive dCK is particularly high in lymphocytes and lymphoid malignancies, although certain solid tumors may also contain the enzyme. The immunoassay of dCK could prove useful in the selection and monitoring of patients who are being treated with nucleosides that are activated by this enzyme.

Increased tyrosine protein kinase activity in hairy cell and monocytic leukemias

Tyrosine protein kinases (TPK) help regulate cellular growth and differentiation. Several proto-oncogenes encode for protein products with associated tyrosine kinase activity. An assay for TPK activity was performed in cell extracts using a synthetic peptide substrate and [32P] adenosine triphosphate (ATP). TPK activity was elevated in K-562 cells, which possess an amplified c-abl oncogene, compared to normal blood mononuclear cells (K-562 = 9.37 +/- 1.72 [mean +/- standard deviation] pmol ATP/10(6) cells/min; normal = 1.14 +/- 0.46, p less than 0.01). TPK activity was measured in peripheral blood mononuclear cells from patients with hairy cell leukemia (HCL), myelomonocytic leukemia (MOL), acute myeloblastic leukemia (AML), and chronic lymphocytic leukemia (CLL). In patients with clinically active disease, elevated TPK activity was measured in mononuclear cells from five HCL patients (range 3.76-24.15) and from seven MOL patients. These elevated levels appeared to parallel disease activity, as low levels of TPK activity were measured in patients with inactive (treated) disease. Low levels of TPK were measured in mononuclear cells from active AML and CLL patients. Elevated TPK levels in patients with HCL and MOL may reflect the overexpression of a proto-oncogene or increased growth factor activity in immature or rapidly dividing leukemic cells. Serial TPK levels in HCL and MOL patients correlated with change in disease activity.

Protein-tyrosine phosphatase activity of hairy cell tartrate-resistant acid phosphatase

Tartrate-resistant acid phosphatase (TRAcP) is a reliable cytochemical marker for the diagnosis of hairy cell leukemia (HCL). The enzyme has been the subject of much biochemical investigation yet its function in the hairy cells (HC) is still unknown. Two TRAcPs have been purified from HCL spleen tissues by a series of chromatographic separations. The two enzymes, provisionally called peak 1 and peak 2, had specific activities of greater than 600 U/mg and 800 U/mg respectively when p-nitrophenyl phosphate (p-NPP) was used as substrate and had Km values in the range of 1 to 5 mM p-NPP. The two TRAcPs had the same substrate specificities and inhibitor sensitivities, therefore could be isoforms of the same enzyme. Their pH optima were between 5 and 6 for all substrates tested including the phosphotyrosine-containing peptide, Raytide, which was still hydrolyzed efficiently at neutral pH. Neither phosphoserine nor phosphoserine-containing casein were hydrolyzed by either enzyme. The TRAcPs of HC may thus be capable of functioning as protein-tyrosine phosphatases (PTP). High activity of a PTP could regulate the activities of protein-tyrosine kinases and thereby influence the growth and differentiation of the hairy cells.

Induction of intracellular and plasma 2',5'-oligoadenylate synthetase by pentostatin

Similar to interferon alpha, pentostatin is highly effective in hairy cell leukemia and moderately active in other chronic lymphoid malignancies. In ten patients with hairy cell leukemia (HCL) and seven patients with other B-cell chronic leukemias (BCL), we have studied the intracellular 2',5'-oligoadenylate synthetase (2,5OAS) activity of the mononuclear cells before, 4 h, 24 h, and 48 h after pentostatin administration. In patients with HCL the median level of intracellular 2,5OAS increased 4.6-fold at 4 h and 11.5-fold at 24 h compared to the pretreatment value. Among the other seven patients, the median intracellular 2,5OAS remained unchanged in three patients and rose slightly by 2 to 14 times in four patients. Eleven patients (eight with HCL and two with BCL) responded to pentostatin. The median increase in 2,5OAS among the responders was 13.0-fold (range 4.8-30.0) whereas that among non-responders was 2.2-fold (range 0.2-6.3). The difference was highly significant (p less than 0.0001). In five of the total seventeen patients, the plasma levels of 2,5OAS activity were also determined and changes in plasma levels paralleled those measured intracellularly. To determine if the elevation of 2,5OAS is mediated by induction of interferon alpha, the expressions of mRNA for interferon alpha and beta were investigated by means of reverse transcription and polymerase chain reaction using the corresponding sense primers. In none of the five patients thus studied could we find an induction of mRNA for interferon alpha or beta in the leukemic cells during treatment with pentostatin. Thus, response to pentostatin correlates with induction of 2,5OAS directly and the 2',5'-oligoadenylate system seems to be involved in cytotoxicity.

Increase in 2',5'-oligoadenylate synthetase caused by deoxycoformycin in hairy cell leukaemia

2',5'-oligoadenylate synthetase (2-5OAS) has been studied in peripheral blood mononuclear cells from nine patients with hairy cell leukaemia (HCL) receiving therapy with the adenosine deaminase inhibitor deoxycoformycin (dCF) or alpha interferon (alpha-IFN). 2-5OAS mRNA was assayed by dot-blot hybridization. Increase of 2-5OAS mRNA level was seen in six patients with HCL treated with dCF and in one patient treated with alpha-IFN who responded to therapy. A patient with a variant form of HCL treated with dCF and the second patient treated with alpha-IFN did not show an increase of 2-5OAS mRNA and neither responded to therapy. The 15 other patients with T or B-chronic lymphoblastic leukaemia (CLL), T-acute lymphoblastic leukaemia (ALL), adult T-cell leukaemia lymphoma (ATLL), non-Hodgkins lymphoma (NHL), Sezary and T or B-prolymphocytic leukaemia (PLL) treated with dCF did not show an increase in 2-5OAS, though four patients, all with T-cell tumours, responded clinically. 2-5OAS activity is known to be stimulated by alpha-IFN and recent work suggests that this rise in 2-5OAS may result in increased cleavage of mRNA for tumour necrosis factor (TNF) and other cytokines on which autocrine growth and proliferation of the tumour cells are dependent. By analogy, we suggest that one mechanism of action of dCF in hairy cell leukaemia may be to break down an autocrine growth loop for TNF or other cytokines. An alternative explanation for these observations is that cytokines released from hairy cells in the bone marrow killed by dCF induce a rise in 2-5OAS in circulating leucocytes.

[Protein kinase activity in lymphoid cells in various forms of lymphoproliferative disorders]

Activities of dipeptidyl-aminopeptidase IV, urokinase-like plasminogen activator, cathepsins B and L were studied in lymphoid cells of patients with various forms of lymphoproliferative disorders. Activity of the enzymes studied was found in all the T- and B-cell, although rate and ratio of the enzymatic activity were dissimilar in various cell types. The highest rate of activity exhibited cells at early stages of maturation obtained from patients with acute lymphoblastic leukemia, while low level of the proteinase activity was detected in cells of patients with chronic lymphoid leukemia, non-Hodgkin lymphoma, hairy cell leukemia and Sezary disease, corresponding to mature T- and B-subpopulations. As shown by analysis of the cells immunological phenotype and their proteolytic activity, the rate of lymphoid cells differentiation correlated with level of proteinases activity. Series of proteinases were firstly studied in human malignant lymphoid cells with known phenotype. The enzyme assay may be used in diagnosis and treatment of patients with lymphoproliferative disorders.

[Lymphoid cell glycosidases in various forms of lymphoproliferative disorders]

Activity of 8 glycosidases (6 acid lysosomal and 2 neutral cytosolic enzymes) was estimated in lymphoid cells of 28 patients with different forms of lymphoproliferative disorders: B- and T-chronic lymphocytic leukemia (CLL), non-Hodgkins lymphoma (NHL), Sezary syndrome, hairy cell leukemia (HCL) and B- and T-acute lymphoblastic leukemia (ALL). Activity of these glycosidases was also studied in mononuclear cells and granulocytes of healthy volunteers and in immature myeloid cells of 16 patients with chronic myeloid leukemia (CML). In lymphoid cells of all the patients studied (except of ALL) the glycosidases activity was decreased as compared with that of normal mononuclear cells and immature myeloid cells. Activity of the majority enzymes studied was higher in T-lymphoid cells of patients with lymphoproliferative disorders as compared with B-cells. The highest glycosidases activity was found in ALL cells and the lowest--in CLL cells of the patients with B-lymphoid cells forms of the disease. Activities of N-acetyl-beta-D-hexosaminidase, alpha-D-mannosidase and beta-D-glucuronidase were distinctly dissimilar in cells of the patients with B-CLL, B-NHL and HCL. Estimation of these glycosidases activity in lymphoid cells may be of importance in differential diagnosis of lymphoproliferative disorders.

[Alpha-L-fucosidase of normal and pathological blood cells]

The glycosidases, enzymes which participate in the degradation of glycoproteins and glycolipids inside the lysosomes are themselves glycoproteins and, for one enzyme, several forms may be isolated in tissues and in biological fluids, corresponding to variations in the composition or the structure of their glycanic moiety. We have previously studied the different forms of alpha-L-fucosidase in human serum, kidney and urine. Some modifications of the glycanic fraction of glycoproteins have been described in various forms of tumoral cells; therefore, we have attempted to verify if the alpha-L-fucosidase of blood cells might be a useful marker in the diagnosis of leukemias, using the enzymic pattern obtained by chromatographic or electrofocusing methods. Detergent extracts from normal lymphocytes, submitted to ion-exchange chromatography as well as to chromatofocusing, revealed the presence of two forms of alpha-L-fucosidase, A and B, with respective pIs of 5.7 and 6.2. After treatment by neuraminidase, these two forms remain distinct, showing that the degrees of sialylation is not the only difference. Moreover, after desialylation, the two forms have not the same affinity for concanavalin A, an argument for the heterogeneity of the glycanic structures. The determination of the total activity, and of enzymic patterns of alpha-L-fucosidase from leukemic cells led to the observation of three types of modifications, in comparison with normal lymphocytes: quantitative variations in the total activity; variations in the proportions of the two forms; variations due to the modification of pIs. We have studied the lymphocytes from four patients with a hairy-cell leukemia (HCL), four patients with chronic lymphoid leukemia (CLL) and the MO cell-line, proceeding from a HCL. In all cases, the total fucosidase activity is strongly decreased in comparison with normal lymphocytes activity. The chromatofocusing pattern for CLL cells reveals the presence of the A and B forms, without modification of their eluting pH. A characteristic pattern is obtained with hairy cells, presenting only the B form, eluted in more acidic conditions. The normal lymphocytes in peripheral blood are for 80 per cent of the T phenotype, and the CLL lymphocytes exhibit the phenotypic markers B, as well as the hairy cells, but the MO cell-line acquires in culture the T markers. As these last cells express both the A and B forms of enzyme, the absence of the A form of alpha-L-fucosidase seems to be a marker of the HCL.(ABSTRACT TRUNCATED AT 400 WORDS)

Evidence that tartrate-resistant acid phosphatases from osteoclastomas and hairy cell leukemia spleen are members of a multigene family

1. Osteoclasts and hairy cell leukemia spleen both contain large amounts of a band 5-tartrate-resistant acid phosphatase (TrACP). 2. We have recently purified to homogeneity a band 5 TrACP from human osteoclastomas and two isoforms of band 5 TrACP (5a and 5b) from the spleen of a patient with hairy cell leukemia. 3. Although the N-terminal amino acid sequences and the apparent molecular weights of the osteoclastoma, hairy cell leukemia spleen TrACPs were identical, there were several differences in the physical and biochemical properties between the three isoenzymes. 4. Based on these findings, it is concluded that these isoenzymes are different enzymes, but that they could have originated from a similar ancestral gene. 5. It is proposed that the osteoclastoma and hairy cell leukemia band 5 TrACPs are members of a multigene family.

Combined effects of interferon and 2'-deoxycoformycin on 2',5'-oligoadenylate synthetase and adenosine deaminase in hairy cell and chronic lymphocytic leukemia cells

The combined effects of interferon (IFN) and 2'-deoxycoformycin (DCF) on 2',5'-oligoadenylate (2-5A) synthetase and adenosine deaminase (ADA) activity were examined in vitro in peripheral blood mononuclear cells from patients with hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL). In HCL cells, the effects of IFN and DCF on both OAS and ADA activity were strictly antagonistic. Antagonism in inducing OAS activity was also observed in CLL cells, although, in general, little interaction between DCF and IFN occurred in these cells. If OAS and ADA are important in the antitumor effects of IFN and DCF, our results suggest that combination therapy with IFN and DCF could be counterproductive.

Comparison of tartrate resistant acid phosphatase in a giant cell bone tumor and a spleen infiltrated with hairy cells

Acid phosphatase (E.C.3.1.3.2) in a giant cell bone tumor and a spleen infiltrated with hairy cells was extracted by citrate buffer and then by 0.3 mol/L NaCl. The cationic acid phosphatase in the crude extract was isolated by CM-cellulose chromatography, and further separated by high pressure liquid chromatography. The majority of the tartrate resistant acid phosphatase in the hairy cell spleen was unabsorbed on CM-cellulose and was insensitive to iron. A much larger portion of the acid phosphatase in the bone tumor, than in the spleen, was cationic and was eluted from the column by 0.8 mol/L NaCl. The cationic acid phosphatase was further separated into consecutive peaks of acid phosphatases with different sensitivity to iron. A major portion of acid phosphatase in the giant cell bone tumor was enhanced by iron, while the amounts of iron-enhanced and iron-insensitive acid phosphatase were about the same in the spleen. The differences of the phosphatases in these two types of pathologic specimens indicate the occurrence of two types of enzymes with different biological significance.

Development of an immunoassay for human serum osteoclastic tartrate-resistant acid phosphatase

A tartrate-resistant acid phosphatase (TrACP), which has been suggested to be very similar to the osteoclastic TrACP, was partially purified from the spleen of a patient with hairy cell leukemia. The purification procedure consisted of carboxymethyl-Sepharose, phosphocellulose, Sephacryl S-200, and phenyl-Sepharose chromatographies. Polyclonal antibodies were generated in guinea pigs with a titer of at least 1:6000. Immunohistochemical staining of fetal rat tibia with the antisera revealed that only the lysosomes of osteoclasts, but not osteoblasts, were stained. An enzyme-linked immunosorbent assay (ELISA) was developed with the antisera. There was no cross-reactivity with 1) partially purified acid phosphatases (ACPs) from normal human and beef spleens, 2) ACPs in extracts of human osteoblastic cells, 3) purified bovine bone matrix TrACP, or 4) commercial prostatic ACP. However, extracts of giant cell bone tumors, containing large amounts of bona fide osteoclasts, showed large amounts of cross-reactive material, which diluted in parallel with the partially purified hairy cell leukemic TrACP in the ELISA. Commercial serum band 5b TrACP also displaced in parallel with the partially purified hairy cell leukemic TrACP. Immunoblotting studies revealed that the antiserum, but not nonimmune guinea pig serum, reacted with the homogeneous hairy cell leukemia splenic band 5 TrACPs, which were recently purified by our laboratory. Preliminary application of the ELISA to sera of patients with metabolic bone diseases revealed that normal healthy individuals had measurable amounts of the immunoreactive material, and patients with Paget's disease or hyperparathyroidism, who should have high bone turnover, had elevated levels of this immunoreactive material in their sera. In contrast, the level of serum osteoclastic TrACP in a patient with an acute lymphatic leukemia was normal. In summary, 1) we have shown that hairy cell leukemia splenic TrACP shares significant immunological similarity with the osteoclastic TrACP and with the serum band 5b TrACP, and 2) the ELISA holds promise for a sensitive and specific assay for bone resorption.

Methods in pathology. Immunophenotype of hairy cell leukemia in paraffin sections

The immunophenotype of hairy cell leukemia (HCL) was investigated using 20 routinely fixed paraffin-embedded tissue sections (12 bone marrows, six spleens, one liver, one lymph node) from 12 patients known to have this disease. A panel of antibodies was used, including anti-leukocyte common antigen (anti-LCA), B-lineage antibodies (LN2, MB2, L26), T-lineage reagents (MT1, UCHL1), monocytic (anti-cathepsin B) and myelomonocytic (anti-lysosyme, Mac 387) antibodies, and other less lineage-specific markers (anti-S-100, anti-alpha-1-antichymotrypsin (anti-alpha 1-ACT), anti-alpha 1-antitrypsin (anti-alpha 1-AT), anti-vimentin). Anti-LCA stained hairy cells in seven of the 12 bone marrows and consistently recognized hairy cells in the spleen, liver, and lymph nodes. Hairy cells generally reacted with B-lineage antibodies and were not labeled by T-lineage markers. No reactivity was noted with myelomonocytic antibodies, anti-S-100, anti-alpha 1-ACT, or anti-alpha 1-AT. Vimentin was expressed in the majority of cases. Tartrate-resistant acid phosphatase reactivity was demonstrated in three of the 20 routinely processed tissue sections. These data suggest that immunohistochemical studies of hairy cell leukemia in routinely processed tissue may be useful in diagnostic hematopathology and surgical pathology.

5' Nucleotidase in chronic B cell leukemias: a cytochemical and ultrastructural study

We studied by cytochemical means the distribution of 5' nucleotidase (5' NT), a purine degradative enzyme, in the circulating lymphocytes of 24 healthy donors and 41 cases of chronic lymphoid leukemias, classified according to morphological and immunological criteria. About half the normal circulating lymphocytes were 5'NT positive and exhibited variable degrees of enzyme activity. Among chronic B lymphocytic leukemias we found high percentages of positive cells only in the phenotypically more mature cases. Moreover all cases of hairy cell, follicular cell, lymphoplasmacytic, and plasma cell leukemia showed moderate or weak 5' NT reactivity. Also one case of chronic T lymphocytic leukemia, CD8 positive, was moderately positive, while another, with large granular lymphocyte morphology, was completely negative. Electron microscopy revealed a discontinuous, granular plasma membrane reaction pattern, varying in intensity from case to case. In conclusion, our results confirm the usefulness of the 5' NT cytochemical reaction for identification of lymphoid populations at different stages of maturation in chronic B cell disorders.

Purification and N-terminal amino acid sequence of the tartrate-resistant acid phosphatase from human osteoclastoma: evidence for a single structure

Tartrate-resistant acid phosphatase type-5 was purified to apparent homogeneity from human osteoclastomas by sequential chromatography on CM-Sepharose, Phenyl-Sepharose, concanavalin A-Sepharose, FPLC Superose-12, and FPLC Mono-S. The purification over the original tissue extract was 1167-fold, with a yield of 16%. An identity in the N-terminal amino acid sequence and Mr was found between this enzyme and two type-5 tartrate-resistant acid phosphatases isolated from hairy cell leukemia spleen. However, they appeared to be different as assessed by amino acid composition. In contrast to a previous report, no evidence was found for two subunits of the tartrate-resistant acid phosphatase.

beta-N-acetylhexosaminidases in the spleen of a patient with hairy-cell leukaemia

The spleen from a patient with hairy-cell leukaemia had beta-N-acetylhexosaminidase activity that could be resolved into three isoenzymes by chromatography on phenyl boronate agarose. Two of these were the major forms, A and B, found in normal tissues but, in addition, there was an 'extra' form that accounted for 15% of total activity. The 'extra' form hydrolysed the synthetic substrate 4-methylumbelliferyl-beta-N-acetylglucosamine 6-sulphate, indicating the presence of alpha-subunits. It was more acidic than A, was less heat-stable and showed no generation of B on denaturation under a variety of conditions. These findings and the immunoblot (Western blotting) analysis demonstrate that the 'extra' form is entirely composed of alpha-subunits, and most closely resembles S, the residual activity in Sandhoff's disease.

Alpha-L-fucosidase isoenzyme pattern in hairy cell leukaemia

alpha-L-Fucosidase isoenzymes pattern in hairy cell leukaemia (HCL) is characterized by the disappearance of the more acidic form when compared to normal lymphocytes. Our data seem to indicate that this profile could not be related to the T or B phenotype because in normal lymphocytes (mainly T), MO cells possessing T markers, as well as lymphocytes from chronic lymphoid leukaemia (CLL) known to exhibit normal-like B phenotypes two alpha-L-fucosidase forms are identified and especially the more acidic one.

Purification and N-terminal sequence of two tartrate-resistant acid phosphatases type-5 from the hairy cell leukemia spleen

Tartrate-resistant acid phosphatases types 5a and 5b were purified from human hairy cell leukemia spleen by sequential chromatography on Phenyl-Sepharose, CM-Sepharose, concanavalin A-Sepharose, FPLC Superose-12 and FPLC Mono-S. The purification over the original tissue extract was 1150- and 3300-fold, with a yield of 2.1% and 2.5%, respectively. Gel filtration indicated an Mr of about 30000 for both forms. There was a N-terminal sequence identity between the two enzymes. However, they appeared to be different as assessed by cation exchange chromatography and amino acid composition.

[Dipeptidyl aminopeptidase-IV in lymphocytes of patients with lymphoproliferative diseases]

DAP-IV activity (Gly-Pro-MCA hydrolysis, pH 7.8) was found in lysates of peripheral blood lymphocytes of patients with T- and B-cell forms of malignant lymphoproliferative diseases. The highest DAP-IV activity was seen in the cells of patients with a rare variant of T-cell lymphocytic leukemia (T-CLL); these cells expressed simultaneously the antigens of T helpers and T suppressors (Th and Ts) (OKT4+ and OKT8+). The DAP-IV activity about ten times less was found in the pathological cells with a phenotype of mature Th (Sezary disease), as well as in the cells expressing antigens of both Ts and natural killers (a rare variant of T-CLL). The same activity was also found in Ts (T gamma-lymphocytosis). The data obtained show that the differences in DAP-IV expression are connected with the differentiation step rather than with the belonging to a particular subpopulation of T-cells. DAP-IV activity, which was somewhat lower than that of T-cells, was found in B-lymphocytes of patients with B-CLL, hair-cellular leukemia, and non-Hodgkin's lymphoma. No correlation of DAP-IV activity with the level of E-cellular differentiation was observed.

Demonstration of the increase in serine esterase-positive T cells in hairy-cell leukemia patients undergoing alpha-interferon therapy

An increased number of serine esterase non-B lymphocytes including CD4+ helper/cytotoxic cells were observed in hairy-cell leukemia patients during (56 +/- 18) and immediately post (52 +/- 16) alpha-interferon therapy compared with pretreatment status (17 +/- 5) and normal donors (29 +/- 3). This increase in lymphocytes bearing one of the putative cytotoxicity-linked proteins was paralleled by a higher cytotoxicity towards K562 cells in the NK and LDCC assays during therapy and similarly, but to a much reduced level, against the hairy-cell derived JOK-1 target cells. Phenotypically, a higher percentage of non-B cells also expressing DR or CD11 antigens were seen in the HCL patients during IFN therapy. In lymphocyte target binding assays, a high affinity of effector to target conjugate formation was observed when either of the hairy cell lines JOK-1 or Hair-M was chosen as targets for IFN-therapy effector cells. Although predominantly CD4+ cells exhibited the in vitro affinity for effector/target conjugation with autologous HCs, the polarisation of serine esterase activity towards the E/T membrane contact area was shown by both CD4+ and CD8+ cells during a short incubation period and before target cell death.

Immunological recovery and dose evaluation in IFN-alpha treatment of hairy cell leukemia: analysis of leukocyte differentiation antigens, NK and 2',5'-oligoadenylate synthetase activity

A low-dose interferon (IFN)-alpha regimen for the treatment of hairy cell leukemia (HCL) was evaluated by following changes in leukocyte differentiation antigens (LDA), natural killer cell (NK) and 2',5'-oligoadenylate (2-5A) synthetase activities. Due to hairy cells' (HC) weak expression of several antigens positive for T cells, B cells, NK cells and monocytes, the use of a double marker specific for hairy cells was needed to distinguish the different subpopulations. Analysis of LDA in peripheral blood (PB) showed a total normalization of the T cell and monocyte numbers within 90 days, the number of NK cells normalized in 90 to 180 d, whereas normalization of B cell number was seen only after 180 to 360 d of treatment. Mean pretreatment 2-5A synthetase activity was normal or low, but upon treatment the levels rose immediately to higher than normal values and remained high throughout the study. Pretreatment NK activity was low, but normalized after between 90 to 360 d, except in 2 patients with severe splenomegaly. In vitro incubation of peripheral blood mononuclear cells (PBMNC) with IFN-alpha induced activation of the NK and 2-5A synthetase activity in untreated patients, but with treatment these effects were gradually abolished, indicating an increasing effect of IFN-alpha in vivo with time. These results shows that the different PBMNC subpopulations and important immunological functions normalize with treatment. This normalization is, however, not seen until at least after 1 year of treatment, indicating that the treatment schedule should be longer. As no exhaustion to the effect of IFN was seen, as measured by the 2-5A synthetase activity, a continuing beneficial effect of treatment is anticipated. The increasing effect of IFN-alpha after the first signs of clinical effect suggests that the doses used in the present study were higher than necessary.

Enzyme activities of leukemic cells and biochemical changes induced by deoxycoformycin in vitro--lack of correlation with clinical response

Deoxycoformycin (DCF) is a specific inhibitor of adenosine deaminase (ADA) and has been shown to be active in lymphoid neoplasms. Cytotoxicity is thought to be mediated by the accumulation of deoxyadenosine (AdR) and deoxyadenosine triphosphate (dATP) which inhibits ribonucleotide reductase and DNA synthesis in rapidly proliferating cells. Others suggested mechanisms leading to cell death particularly in non-dividing cells include depletion of ATP and NAD pools, inhibition of S-adenosylhomocysteine (SAH) hydrolase and induction of DNA strand breaks. In patients with high leukemic counts who were subsequently treated with DCF, we have studied (a) the levels of ADA, ecto-5'-nucleotidase (5NT), deoxyadenosine kinase (AdR-kinase) and SAH-hydrolase in the leukemic cells; [b) the in-vitro effects of DCF on dATP, ATP, NAD, SAH-hydrolase levels and on DNA strand breaks; and (c) the correlation between these parameters with clinical response to DCF. No significant difference in ADA, 5NT, AdR-kinase and SAH-hydrolase activities could be found between responders and non-responders. Incubation of the leukemic cells in vitro with DCF caused an inhibition of ADA, an accumulation of dATP, a moderate reduction in ATP and NAD levels, a suppression of SAH-hydrolase activity and an increase in DNA strand breaks in practically all the leukemic samples, irrespective of clinical response. Our results show that neither measurement of these enzymes nor studies of these biochemical sequelae of ADA inhibition in vitro predicts clinical responsiveness to DCF therapy.

In vivo and in vitro induction of (2'-5') oligoadenylate synthetase by human interferons in leukocytes from healthy donors and patients with renal cancer and hairy cell leukemia

The effect of in vivo administered interferon-alpha (IFN-alpha) on 2-5-oligoadenylate (A) synthetase activity of peripheral blood mononuclear cells (PBMC) was compared in patients with hairy cell leukemia and renal cell cancer. Basic levels of this enzyme varied from donor to donor, but mean levels were not significantly different in patients with renal cell cancer or hairy cell leukemia compared to healthy donors. After a single injection of 3 x 10(6) IU IFN, these basic levels rose 2- to 8-fold within 12-24 h post-injection and reverted to pretreatment levels after 48 h. The extent of this in vivo stimulation by IFN-alpha was similar in patients with hairy cell leukemia and renal cell carcinoma, and was correlated with down-regulation of IFN-alpha receptors. The in vitro effects of IFN-alpha, -beta and -gamma were compared after 18 h treatment with 10, 10(2) and 10(3) IU/ml of each IFN. Unlike IFN-alpha and -beta, IFN-gamma did not induce 2-5 A synthetase activity in either normal PBMC or hairy cells; these results were related to the effects of the three IFN on proliferative response of normal PBMC to phytohemagglutinin. Our data support the idea that 2-5 A synthetase activity is a marker of biological response to interferon treatment in human cancers.

Cytochemistry of tartrate-resistant acid phosphatase: 15 years' experience

Tartrate-resistant acid phosphatase (T-AcP) has been used in the past 15 years as a specific test for the diagnosis of hairy cell leukemia (HCL). However, enzyme activity has been reported to be absent from the hairy cells of rare cases of HCL and to be present in the neoplastic cells of diseases other than HCL. In order to fully utilize T-AcP for the diagnosis of HCL, it is necessary to maximize the sensitivity and specificity of the staining method, to have adequate quality control to ensure technical and interpretative accuracy, and to prepare optimal cytologic and histologic materials for study. In blood, only the presence of cells with intense T-AcP activity is diagnostic of HCL (positive T-AcP test). In tissues other than blood, the presence of cells with intense enzyme activity may not be diagnostic for HCL; assessment of cell morphology and appreciation of the pattern of enzyme localization are also important. In studying the blood of over 1,000 patients, we have found a negative T-AcP test in two of 200 cases of HCL and a positive T-AcP test in three of 800 patients with diseases other than HCL. We believe that the T-AcP test, when performed and interpreted properly, is a useful diagnostic test for HCL.

Enzymes of purine metabolism in hairy cell leukemia

Differences in activities of the purine degradative enzymes, adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), and 5'-nucleotidase (5'NT), have been observed among different classes of lymphoid malignancies. Recent studies have shown that hairy cell leukemia (HCL) may respond to treatment with the ADA inhibitor, 2-deoxycoformycin. This study demonstrates that the cells of HCL have significantly lower levels of ADA and 5'NT (P always less than 0.01) when compared to levels in normal B- or T-lymphocytes, but have higher levels of PNP (P less than 0.001 for both comparisons). Recent studies have shown that when treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA), cells of B-cell chronic lymphatic leukemia (B-CLL) acquire phenotypic characters of HCL. The authors have therefore also investigated the changes in enzyme pattern of B-CLL after incubation with TPA B-CLL cells are characterized by low levels of ADA, PNP, and 5'-NT, but TPA caused a marked increase in PNP activity (P less than 0.001, t test for paired samples), a pattern similar to HCL. The results from biochemical studies are thus in accordance with the hypothesis that HCL cells are more mature than B-CLL cells. The special enzyme profile of HCL suggests that a PNP inhibitor might also be effective in the treatment of this disease.

Induction of features characteristic of hairy cell leukemia in chronic lymphocytic leukemia and prolymphocytic leukemia cells

In vitro maturation was induced with 12-O-tetradecanoylphorbol-13-acetate in leukemic cell samples from patients with chronic lymphocytic leukemia (n = 10) and prolymphocytic leukemia (n = 4). The cells were studied for morphology, for immunological markers using the fluorescence activated cell sorter, and for acid phosphatase isoenzymes using both cytochemistry and isoelectrofocusing. Morphologically the induced changes included appearance of cells with an excentric nucleus and basophilic cytoplasm and eventually of cells with many fine cytoplasmic projections ("hairs"). Analysis of immunological markers by flow cytometry revealed that the monoclonal antibody defined cell surface molecule HD6 (CD22), which is strongly expressed on hairy cell leukemia (HCL) but absent from plasmacytoma and plasma cells, can be induced or enhanced in the leukemic samples. In the study of acid phosphatase isoenzymes using cytochemistry we observed the induction of the tartrate resistant isoenzyme. Further, using isoelectrofocusing we could demonstrate the induction of the same band of tartrate resistant acid phosphatase with an isoelectric point of 9.0-9.7 as detected also in HCL. This particular isoenzyme is considered characteristic of HCL but is absent in plasmacytoma. Our data demonstrate that chronic lymphocytic leukemia and prolymphocytic leukemia cells can be induced to realize a common genetic program which bears characteristics of HCL, indicating that these three entities are much more closely related than previously thought.

Uracil-DNA glycosylase activity in chronic lymphoproliferative disorders

The activity of uracil-DNA glycosylase, a repair enzyme for the excision of uracil from DNA, was studied in patients with chronic lymphoproliferative disorders and with malignant plasma cell dyscrasias. The biochemical assay was performed on mononuclear cells, isolated by density gradient centrifugation from peripheral blood, from bone marrow or from both. The activity of the uracil-DNA glycosylase of peripheral blood cells in 8/8 cases of myeloma and in 3/3 cases of Waldenström's macroglobulinemia was in the same range as in 22 non-hematological control patients, i.e. 2.4-25.1 U/mg of protein. Higher activities were found in 9/12 cases of chronic lymphocytic leukemia (CLL), in 2/4 cases of hairy cell leukemia (HCL), in 2/2 cases of chronic T-cell lymphocytosis and in the only case of small cell lymphocytic lymphoma. Follow-up of some CLL and HCL patients revealed that uracil-DNA glycosylase activity was fairly stable during the course of the disease. We conclude that malignant cells in chronic lymphoproliferative disorders are characterized by a normal or even increased capability to repair DNA, as exemplified by uracil-DNA glycosylase in this study.

Bone marrow changes in patients with hairy cell leukemia treated by recombinant alpha 2-interferon

Bone marrow specimens from 21 patients with hairy cell leukemia (HCL) who were entered into a program to study the efficacy of treatment with recombinant alpha 2-interferon were evaluated. Patients were treated with the interferon, 2 X 10(6) U/m2 subcutaneously three times weekly, and were scheduled to undergo bone marrow aspiration and biopsy at study entry and after three (21 patients) and six (16 patients) months of treatment. Bone marrow samples after three months of treatment showed an overall decline in cellularity, from an average of 77 +/- 20 to 57 +/- 22 per cent, with a marked decrease in the percentage of neoplastic mass (from 87 +/- 9 to 59 +/- 24 per cent). The bone marrow changes were associated with significant improvement in hematologic values, including hemoglobin levels and granulocyte and platelet counts. The bone marrow changes and improved hematologic values remained stable with continuation of interferon therapy. However complete bone marrow remission did not occur in any of the patients after three or six months of interferon therapy. The HCL cell mass in more than 60 per cent of the patients remained at or above 50 per cent of the marrow cellularity and dropped to less than 25 per cent in 14 per cent of the patients. In all of the patients increased amounts of reticulin fibers were identified in the bone marrow prior to therapy, and 89 per cent of bone marrow aspirations failed (dry tap). The amounts of reticulin fibers remained increased in most of the patients (91 per cent), with a high incidence of dry taps (73 per cent), after therapy. Interferon therapy also changed the tartrate-resistant acid phosphatase(TRAP)-positive HCL cells to TRAP-negative, suggesting inhibition of activity and/or production of TRAP in HCL cells.

The type 5, acid phosphatase from spleen of humans with hairy cell leukemia. Purification, properties, immunological characterization, and comparison with porcine uteroferrin

The spleens of patients with hairy cell leukemia contain high levels of a tartrate-insensitive, cationic, acid phosphatase (the human Type 5 isozyme). This phosphatase has been purified by a procedure which involves only two chromatographic steps: CM-cellulose chromatography and immunoaffinity chromatography on sheep antibodies generated against porcine uteroferrin. Uteroferrin is an abundant iron-containing acid phosphatase that can be recovered readily from porcine uterine secretions. Like uteroferrin, the purified human Type 5 phosphatase is a glycoprotein of molecular weight about 34,000. It contains two atoms of iron/molecule. The human phosphatase and uteroferrin also resemble each other closely in electrophoretic mobility, substrate specificity, and response to a variety of activators and inhibitors. Mouse monoclonal antibodies have been raised to uteroferrin and to the human Type 5 phosphatase. Three monoclonal antibodies which bind with high affinities to distinct sites on the uteroferrin molecule also recognize the human spleen enzyme, but bind to it with much lower affinity. These antibodies also recognize cationic acid phosphatases purified from bovine and rat spleens. A monoclonal antibody raised against the human enzyme, but selected for binding to uteroferrin, appears to recognize a relatively conserved site on all four phosphatases. We conclude that the human Type 5 isozyme belongs to a growing class of structurally related, iron-containing acid phosphatases which includes the iron-transport protein, uteroferrin.