Isoenzyme studies in human leukemia-lymphoma cell lines--1. Carboxylic esterase

Enhancer Hijacking Drives Oncogenic BCL11B Expression in Lineage-Ambiguous Stem Cell Leukemia

Lineage-ambiguous leukemias are high-risk malignancies of poorly understood genetic basis. Here, we describe a distinct subgroup of acute leukemia with expression of myeloid, T lymphoid, and stem cell markers driven by aberrant allele-specific deregulation of BCL11B, a master transcription factor responsible for thymic T-lineage commitment and specification. Mechanistically, this deregulation was driven by chromosomal rearrangements that juxtapose BCL11B to superenhancers active in hematopoietic progenitors, or focal amplifications that generate a superenhancer from a noncoding element distal to BCL11B. Chromatin conformation analyses demonstrated long-range interactions of rearranged enhancers with the expressed BCL11B allele and association of BCL11B with activated hematopoietic progenitor cell cis-regulatory elements, suggesting BCL11B is aberrantly co-opted into a gene regulatory network that drives transformation by maintaining a progenitor state. These data support a role for ectopic BCL11B expression in primitive hematopoietic cells mediated by enhancer hijacking as an oncogenic driver of human lineage-ambiguous leukemia. SIGNIFICANCE: Lineage-ambiguous leukemias pose significant diagnostic and therapeutic challenges due to a poorly understood molecular and cellular basis. We identify oncogenic deregulation of BCL11B driven by diverse structural alterations, including de novo superenhancer generation, as the driving feature of a subset of lineage-ambiguous leukemias that transcend current diagnostic boundaries.This article is highlighted in the In This Issue feature, p. 2659.

Options for imaging cellular therapeutics in vivo: a multi-stakeholder perspective

Cell-based therapies have been making great advances toward clinical reality. Despite the increase in trial activity, few therapies have successfully navigated late-phase clinical trials and received market authorization. One possible explanation for this is that additional tools and technologies to enable their development have only recently become available. To support the safety evaluation of cell therapies, the Health and Environmental Sciences Institute Cell Therapy-Tracking, Circulation and Safety Committee, a multisector collaborative committee, polled the attendees of the 2017 International Society for Cell & Gene Therapy conference in London, UK, to understand the gaps and needs that cell therapy developers have encountered regarding safety evaluations in vivo. The goal of the survey was to collect information to inform stakeholders of areas of interest that can help ensure the safe use of cellular therapeutics in the clinic. This review is a response to the cellular imaging interests of those respondents. The authors offer a brief overview of available technologies and then highlight the areas of interest from the survey by describing how imaging technologies can meet those needs. The areas of interest include imaging of cells over time, sensitivity of imaging modalities, ability to quantify cells, imaging cellular survival and differentiation and safety concerns around adding imaging agents to cellular therapy protocols. The Health and Environmental Sciences Institute Cell Therapy-Tracking, Circulation and Safety Committee believes that the ability to understand therapeutic cell fate is vital for determining and understanding cell therapy efficacy and safety and offers this review to aid in those needs. An aim of this article is to share the available imaging technologies with the cell therapy community to demonstrate how these technologies can accomplish unmet needs throughout the translational process and strengthen the understanding of cellular therapeutics.

Massive clonal expansion of polycytotoxic skin and blood CD8+ T cells in patients with toxic epidermal necrolysis

Toxic epidermal necrolysis (TEN) is a life-threatening cutaneous adverse drug reaction. To better understand why skin symptoms are so severe, we conducted a prospective immunophenotyping study on skin and blood. Mass cytometry results confirmed that effector memory polycytotoxic CD8⁺ T cells (CTLs) are the main leucocytes in TEN blisters at the acute phase. Deep T cell receptor (TCR) repertoire sequencing identified massive expansion of unique CDR3 clonotypes in blister cells. The same clones were highly expanded in patient's blood, and the degree of their expansion showed significant correlation with disease severity. By transducing α and β chains of the expanded clonotypes into a TCR-defective cell line, we confirmed that those cells were drug specific. Collectively, these results suggest that the relative clonal expansion and phenotype of skin-recruited CTLs condition the clinical presentation of cutaneous adverse drug reactions.

Characterization of Human Mucosal-associated Invariant T (MAIT) Cells

Mucosal-associated invariant T (MAIT) cells are a subset of unconventional T cells restricted by the major histocompatibility complex (MHC) class I-like molecule MHC-related protein 1 (MR1). MAIT cells are found throughout the body, especially in human blood and liver. Unlike conventional T cells, which are stimulated by peptide antigens presented by MHC molecules, MAIT cells recognize metabolite antigens derived from an intermediate in the microbial biosynthesis of riboflavin. MAIT cells mediate protective immunity to infections by riboflavin-producing microbes via the production of cytokines and cytotoxicity. The discovery of stimulating MAIT cell antigens allowed for the development of an analytical tool, the MR1 tetramer, that binds specifically to the MAIT T cell receptor (TCR) and is becoming the gold standard for identification of MAIT cells by flow cytometry. This article describes protocols to characterize the phenotype of human MAIT cells in blood and tissues by flow cytometry using fluorescently labeled human MR1 tetramers alongside antibodies specific for MAIT cell markers. © 2019 by John Wiley & Sons, Inc. The main protocols include: Basic Protocol 1: Determining the frequency and steady-state surface phenotype of human MAIT cells Basic Protocol 2: Determining the activation phenotype of human MAIT cells in blood Basic Protocol 3: Characterizing MAIT cell TCRs using TCR-positive reporter cell lines Alternate protocols are provided for determining the absolute number, transcription factor phenotype, and TCR usage of human MAIT cells; and determining activation phenotype by staining for intracellular markers, measuring secreted cytokines, and measuring fluorescent dye dilution due to proliferation. Additional methods are provided for determining the capacity of MAIT cells to produce cytokine independently of antigen using plate-bound or bead-immobilized CD3/CD28 stimulation; and determining the MR1-Ag dependence of MAIT cell activation using MR1-blocking antibody or competitive inhibition. For TCR-positive reporter cell lines, methods are also provided for evaluating the MAIT TCR-mediated MR1-Ag response, determining the capacity of the reporter lines to produce cytokine independently of antigen, determining the MR1-Ag dependence of the reporter lines, and evaluating the MR1-Ag response of the reporter lines using IL-2 secretion. Support Protocols describe the preparation of PBMCs from human blood, the preparation of single-cell suspensions from tissue, the isolation of MAIT cells by FACS and MACS, cloning MAIT TCRα and β chain genes and MR1 genes for transduction, generating stably and transiently transfected cells lines, generating a stable MR1 knockout antigen-presenting cell line, and generating monocyte-derived dendritic cells.

Application of Chromosome Conformation Capture Method for Detection MYC/TRD Chromosomal Translocation in Leukemia Cell Line

Background: Chromosomal breakpoints are the most common cause of hereditary diseases and cancers. Today, many standard clinical methods such as cytogenetic and PCR based techniques are used which have limitation regarding detection resolution. Chromosome conformation capture is a method for detecting gene proximity and chromosomal rearrangements.

Materials and Methods: In this study, SKW3 cell line was used for detecting t(8;14)(q24;q11) using a 3C-based technique. SKW3 cell line was used for 3C library preparation. For Inverse PCR, two regions were selected in upstream and downstream of the viewpoint locus on chromosome 8-MYC gene based on EcoRI restriction sites. The captured sequence with intra-chromosomal interaction between chr8-c-MYC and chr14-TRD was selected for the translocation PCR primer design.

Results: The DNA fragment captured in 3C PCR showed a specific TRD sequence translocated downstream of the MYC gene. Translocation PCR demonstrated the existence of (8; 14) (q24; q11) MYC /TRD in both library and genomic DNA.

Conclusion: This result demonstrated 3C- based method could be used as a useful low-cost easy operating technique in chromosomal rearrangements detection. In this study, the integration of whole genome library monitoring and PCR method was used as a high- through put method in chromosomal breakpoints detection.

Novel proteasome-inhibitory syrbactin analogs inducing endoplasmic reticulum stress and apoptosis in hematological tumor cell lines

The proteasome has been recognized as a druggable target in cancer cells, and this has led to searches for pharmacologic agents that target this cellular organelle for cancer therapeutic purposes. Syrbactins are a group of microbial metabolites consisting of two related families, the glidobactins and the syringolins. Some members of this group have revealed cytotoxic efficacy in tumor cells, and more recently it was discovered that they exert proteasome-inhibitory function. Based on this therapeutic promise and to gain further understanding of their molecular modes of action, we chemically synthesized de-novo three novel syrbactin analogs and characterized their proteasome-inhibitory and in vitro anti-neoplastic activity in human cell lines representing multiple myeloma, Waldenström's macroglobulinemia, and lymphocytic leukemia. Our results show that two of these novel compounds are able to inhibit proteasome activity in the nanomolar range, reduce the expression of anti-apoptotic proteins survivin and Mcl-1, and cause severe endoplasmic reticulum (ER) stress, resulting in pronounced tumor cell death. These anticancer effects can be synergistically enhanced when the agents are combined with thapsigargin, which further aggravates ER stress by a different mechanism. Taken together, our findings support the notion that syrbactin analogs may provide a structural platform for the development of novel cancer therapeutics, and that their efficacy may be further increased when complemented with other agents that trigger ER stress.

Somatic mutations and intraclonal variations in the rearranged Vkappa genes of B-non-Hodgkin's lymphoma cell lines

Three established Burkitt's lymphoma (BL) cell lines (Daudi, Raji and DG-75) and three B-non-Hodgkin's lymphoma (B-NHL) of other types (Pfeiffer, Farage and Toledo) were analyzed with respect to the presence of somatic point mutations in their rearranged immunoglobulin Vkappa genes. Two of the Vkappa sequences of BL and two of those of the B-NHL were heavily mutated (up to 11%), when compared with their closest germline variable region counterparts ("clonal mutations"). Only one of the six cell lines contained an unmutated germline Vkappa sequence. The clonal mutations have features characteristic of the mutation machinery operating in the course of the T-dependent immune response, such as a preference of mutations in purine bases, more transitions than transversions and targeting to CDR and to known "hotspot" motifs. Sequence variations among different Vkappa PCR clones isolated from each of the cell lines ("intraclonal mutations") showed that the Vkappa of Toledo exhibited about 5-fold higher mutation frequency (MF) than the background level of Taq polymerase error (approximately 0.12% mut/bp). Similarly, the MF of Vkappa of two of the BL cell lines was 3-4-fold higher than the Taq polymerase misincorporation rate. In contrast, the mutation frequencies of the Vkappa of DG-75, Farage and Pfeiffer did not significantly exceed the level of Taq polymerase error. Our combined results show that 5 out of the 6 B-cell lines studied originated from B-cells that have already somatically mutated in vivo their rearranged Vkappa genes. Moreover, two of the Burkitt's and one of the B-NHL cell lines exhibit intraclonal variation indicating that the process of somatic hypermutation continued following the neoplastic event, either in vivo or in culture. These results are in accord with the presumed origin of the majority of the BL and some types of the B-NHL, from centrocytes or centroblasts of the germinal centers in which the process of somatic hypermutation is taking place.

Heterogeneity of T-acute lymphoblastic leukemia (T-ALL) cell lines: suggestion for classification by immunophenotype and T-cell receptor studies

Hematopoietic cell lines are often used as representatives for a certain cell differentiation lineage and stage, particularly in immunological and hematological studies. Acute lymphoblastic leukemia (ALL) of T-cell type is a rather heterogeneous group of ALL at least by immunophenotyping. Our aim was to present a comprehensive characterization of frequently used T-cell leukemia cell lines and to suggest a correlation with the normal differentiation pattern. A total of 16 T-ALL cell lines were analyzed for their immunophenotype and for T-cell receptor (TCR) rearrangement and expression. The panel of 20 cell surface markers included two new monoclonal antibodies (MoAb), TC-12 and TH-111, which were raised in our laboratory and detect subpopulations of T-cell ALL. TC-12 was typed 'unique', TH-111 was assigned to the CD96 cluster at the Vth Conference on human leucocyte differentiation antigens (HLDA). We categorized the 16 cell lines into the four groups pro-T, pre-T, cortical T and mature T differentiation stage according to the recent proposal of the European Group for the Immunological Characterization of Leukemias (EGIL). Interestingly, none of the T-cell lines were found to be alike. In conclusion, it appears necessary to consider the particular differentiation stage of each individual cell line when using T-cell leukemia lines as models for malignant or normal T cells.

Molecular cloning of human and bovine LECT2 having a neutrophil chemotactic activity and its specific expression in the liver

We previously reported the purification and amino acid sequence of a novel neutrophil chemotactic protein termed LECT2 (leukocyte cell-derived chemotaxin 2). In this paper we report molecular cloning of human and bovine LECT2 cDNAs based on the amino acid sequence of the purified protein. The deduced amino acid sequence of human LECT2 (hLECT2) shows an 86% identity to bovine LECT2 (bLECT2). The deduced primary structures of LECT2 were highly homologous to the repeated units of Mim-1 protein (myb induced myeloid protein-1). The mim-1 gene is one of the known myb target genes and is specifically expressed in normal and transformed immature granulocytes in the chicken. Northern blot analysis of normal human tissues demonstrated that the hLECT2 gene is specifically expressed in the adult and fetal livers. In addition, several human hepatoma cell lines also expressed LECT2 mRNA, suggesting that hepatic cells in the liver produce LECT2 protein.

Purification and primary amino acid sequence of a novel neutrophil chemotactic factor LECT2

We purified a neutrophil chemotactic factor from a culture fluid of the PHA-activated human T-cell leukemia SKW-3 cells. The factor showed a 16-kDa basic protein by Tricin-SDS-polyacrylamide gel electorophoresis and analysis of amino acid composition. The primary amino acid sequence revealed that the chemotactic factor was significantly different from other known chemotactic factors, indicating a novel protein designated LECT2. The sequence revealed homology with the myb-induced myeloid protein-1 (Mim-1), which is expressed from gene in immature and normal granulocytes of chicken. Its biological function had not yet been identified. LECT2 and Mim-1 may be involved in the regulation of neutrophil functions in an as yet unidentified way.

Expression and modulation of annexin VIII in human leukemia-lymphoma cell lines

Annexin VIII is a calcium- and phospholipid-binding protein with anticoagulant activity. Annexin VIII mRNA was found to be specifically expressed in acute promyelocytic leukemia (APL) cells; it was not found in other types of acute myeloid leukemia (AML) nor in lymphoid malignancies. Using Northern blot analysis we investigated annexin VIII expression in 142 continuous human leukemia and lymphoma cell lines at the mRNA level. While the only APL cell line, NB-4, was indeed positive, other cell lines also displayed annexin VIII mRNA: 4/22 myeloid cell lines, 8/23 monocytic cell lines, 2/8 megakaryoblastic cell lines, 5/26 lymphoma-derived cell lines, 2/10 myeloma cell lines and 1/44 lymphoid leukemia cell lines. The strongest expression was seen in NB-4 and in the Hodgkin's disease derived cell line HDLM-2. Treatment of NB-4 cells with all-trans retinoic acid (ATRA) or the phorbol ester TPA induced terminal differentiation and down-regulated annexin VIII mRNA expression rapidly within a few hours; vitamin D3 was ineffective in this regard; the protein kinase C activator Bryostatin 1 up-regulated the expression. A panel of initially negative cell lines could not be induced by any of these biomodulators to transcribe annexin VIII. The half-life (T1/2) of annexin VIII mRNA was about 3-4 h using actinomycin D as transcription inhibitor. Treatment with ATRA or TPA prior to exposure to actinomycin shortened the T1/2 to 2 h while Bryostatin 1 extended it to 6h. As 21/141 non-APL cell lines were positive, annexin VIII cannot be used as a marker gene for APL cells; however, it might be associated with myelomonocytic or erythro-megakaryoblastic precursor cells. Annexin VIII gene expression might play a unique role in the proliferation and/or differentiation of leukemic cells and could be associated with the particular abnormal hemostasis of some leukemias.

Differentiation and growth modulation of myeloid leukemia cells by the protein kinase C activating agent bryostatin-1

Bryostatin-1 (Bryo), a macrocyclic lactone of the sea water bryozoan Bugula neritina, is a potent activator of protein kinase C and was found to exhibit antineoplastic activity in several systems. We studied the effect of Bryo on differentiation and growth modulation of human myeloid leukemia cell lines and freshly explanted blood cells from patients with myeloid leukemia. Alterations at the molecular level and phenotypic changes triggered by Bryo were similar, but not identical, to those induced by phorbol esters. Bryo was able to inhibit cellular proliferation as evidenced by [3H]-thymidine uptake and induced morphological changes associated with monocytic differentiation. In studies using continuous cell lines, the glucocorticoid dexamethasone was unable to prevent the Bryo-induced growth inhibition or the induced phenotypic changes. However, in fresh myeloid blood cells dexamethasone attenuated these Bryo-triggered effects. Our own data taken together with reports from the literature reviewed here suggest the following conclusions: (i) Bryo, while lacking tumor promoting activity, is able to induce differentiation in maturation arrested leukemia cells; (ii) it exhibits selective antiproliferative properties in normal or malignant hematopoietic cells and supports growth of multipotent stem cells. These features might qualify Bryostatin-1 as a potential candidate for promising research and possibly for future clinical applications.

Induced thermotolerance to apoptosis in a human T lymphocyte cell line

A brief exposure to elevated temperatures elicits, in all organisms, a transient state of increased heat resistance known as thermotolerance. The mechanism for this thermotolerant state is unknown primarily because it is not clear how mild hyperthermia leads to cell death. The realization that cell death can occur through an active process of self destruction, known as apoptosis, led us to consider whether thermotolerance provides protection against this mode of cell death. Apoptosis is a common and essential form of cell death that occurs under both physiological and pathological conditions. This mode of cell death requires the active participation of the dying cell and in this way differs mechanistically from the alternative mode of cell death, necrosis. Here we show that mild hyperthermia induces apoptosis in a human leukemic T cell line. This is evidenced by chromatin condensation, nuclear fragmentation and the cleavage of DNA into oligonucleosome size units. DNA fragmentation is a biochemical hallmark of apoptosis and requires the activation of an endogenous endonuclease. The extent of DNA fragmentation was proportional to the severity of heat stress for cells heated at 43 degrees C from 30 to 90 minutes. A brief conditioning heat treatment induced a resistance to apoptosis. This was evident as a resistance to DNA fragmentation and a reduction in the number of apoptotic cells after a heat challenge. Resistance to DNA fragmentation developed during a recovery period at 37 degrees C and was correlated with enhanced heat shock protein (hsp) synthesis. This heat-induced resistance to apoptosis suggests that thermotolerant cells have gained the capacity to prevent the onset of this pathway of self-destruction. An examination of this process in heated cells should provide new insights into the molecular basis of cellular thermotolerance.

Monocyte-specific esterase isoenzyme demonstrated by isoelectric focusing

Using horizontal thin-layer isoelectric focusing in polyacrylamide gels, we separated the isoenzymes of carboxylic esterase (EC 3.1.1.1) of cell extracts prepared from human hematopoietic cells. Isoenzyme bands were visualized by staining with naphthol ester as substrate and coupling to an azo dye. Staining intensities of isoenzymes were quantified by densitometric scanning. On isoelectric focusing in a pH 2-11 gradient, distinct esterase isoenzyme profiles could be discerned and correlated to various types of normal hematopoietic cells and their leukemic counterparts. One unique isoenzyme, termed monoband, could be clearly identified on the basis of its isoelectric point (pI 6.0), its strong expression by normal and malignant monocytes and its complete and selective inhibition by sodium fluoride. This band was only found in monocytes of either normal or leukemic origin, but not in lymphoid or myeloid cells. The monocyte esterase could be inhibited by sodium fluoride whereas other isoenzyme bands were resistant to this inhibition. However, the specificity of this inhibitory reaction was relative, depending on the concentration of sodium fluoride. Compared with normal monocytes, leukemic monocytes often showed an overexpression of the mono-bands. Dilution experiments established the distinct prominence of the mono-band which could be detected among the other isoenzymes even when only 1% of the total cell population consisted of monocytes. Immature myeloid, but mono-band negative leukemic cells whose arrest of differentiation can be overcome by in vitro 12-O-tetradecanoylphorbol 13-acetate-promoted differentiation to more mature cells, could be induced to express the mono-band which paralleled their maturation to monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

The human protooncogene product p33pim is expressed during fetal hematopoiesis and in diverse leukemias

We measured the human pim-1 protooncogene (PIM) expression during fetal development and in hematopoietic malignancies. Our data indicate that during human fetal hematopoiesis the 33-kDa pim product, p33pim, is highly expressed in the liver and spleen. In contrast, at the adult stage it is only slightly expressed in circulating granulocytes. Out of 70 hematopoietic malignancies analyzed, 51 patients and 19 cell lines, p33pim was overexpressed in approximately 30% of the samples, particularly in myeloid and lymphoid acute leukemias. This overexpression was unrelated to any stage of cellular differentiation and was not due to gene rearrangement or amplification. These results imply a physiological role of the pim-1 protooncogene during hematopoietic development and a deregulation in various leukemias.

Expression of protein kinase C subspecies in human leukemia-lymphoma cell lines

Expression of protein kinase C (PKC) subspecies was studied in various human leukemia-lymphoma cell lines. The PKC in most cell lines examined was resolved into two major fractions corresponding to type II (beta-sequence) and type III (alpha-sequence) PKC of the rat brain. The amounts of these two subspecies greatly varied among the cell lines. Type I PKC (gamma-sequence) was expressed in none of the cell lines tested, but PKCs with undefined structures were frequently detected. The differential co-expression of several PKC subspecies is presumably related to the state of cell differentiation.

Morphological, immunophenotypical and isoenzymatic profiles of human leukemia cells and derived T-cell lines

Six monoclonal leukemia cell lines (MOLT 12-17) were established from three patients with acute leukemia. Two of the patients' samples were of the T-ALL type, the third had morphological, isoenzymatic and immunological features of AMoL. The cell lines resulting from these original cells displayed distinct, but stable marker profiles. A comparison between primary cells and resulting cell lines showed that the cell lines established from patients with T-ALL (MOLT 12, 13, 14 and MOLT 16, 17) expressed similar phenotypes and isoenzyme patterns, but were different in a few specific aspects. The changes suggest a modulation of marker expression in vitro or an arrest at a more immature stage of differentiation than the original cells. The cell line MOLT 15 established from the case of AMoL exhibited a quite discordant profile when compared to the primary sample: the cells lacked all previously found myelomonocytic antigens and a monocyte-specific esterase isoenzyme, but expressed the T-cell associated CD7 antigen and had rearrangements and RNA transcripts of the T-cell receptor beta and gamma chain genes. This striking discrepancy between the patient's malignant cells and the corresponding cell line suggests that subpopulation selection had occurred in culture.

Mutations in the human adenosine deaminase gene that affect protein structure and RNA splicing

Adenosine deaminase (ADA; adenosine aminohydrolase, EC 3.5.4.4) deficiency is one cause of the genetic disease severe combined immunodeficiency. To identify mutations responsible for ADA deficiency, we synthesized cDNAs to ADA mRNAs from two cell lines, GM2756 and GM2825A, derived from ADA-deficient immunodeficient patients. Sequence analysis of GM2756 cDNA clones revealed a different point mutation in each allele that causes amino acid changes of alanine to valine and arginine to histidine. One allele of GM2825A also has a point mutation that causes an alanine to valine substitution. The other allele of GM2825A was found to produce an mRNA in which exon 4 had been spliced out but had no other detrimental mutations. S1 nuclease mapping of GM2825A mRNAs showed equal abundance of the full-length ADA mRNA and the ADA mRNA that was missing exon 4. Several of the ADA cDNA clones extended 5' of the major initiation start site, indicating multiple start sites for ADA transcription. The point mutations in GM2756 and GM2825A and the absence of exon 4 in GM2825A appear to be directly responsible for the ADA deficiency. Comparison of a number of normal and mutant ADA cDNA sequences showed a number of changes in the third base of codons. These changes do not affect the amino acid sequence. Analyses of ADA cDNAs from different cell lines detected aberrant RNA species that either included intron 7 or excluded exon 7. Their presence is a result of aberrant splicing of pre-mRNAs and is not related to mutations that cause ADA deficiency.

T-leukemia cell lines CCRF-CEM, HPB-ALL, JM and MOLT-4: changes in isoenzyme profiles during induction of differentiation

Biochemical analysis has been used to monitor the induction of differentiation in cultured human T-leukemia cell lines (CCRF-CEM, HPB-ALL, JM and MOLT-4) by the phorbolester 12-0-tetradecanoylphorbol 13-acetate (TPA). The isoenzymes of carboxylic esterase, acid phosphatase, hexosaminidase and lactate dehydrogenase were separated by isoelectric focusing on horizontal thin-layer polyacrylamide gels and stained by histo-cytochemical methods. TPA inhibited the proliferative activity in all four cell lines and led to aggregation of cells seen as floating clusters. TPA induced an increase in number and staining intensity of isoenzymes of all four enzymes in the cell lines studied. This corresponds to an induced isoenzymatic maturation as the progressive increase in number and staining intensity of the isoenzymes parallels the differentiation along the T-cell pathway. However, regardless of the initial stage of arrested differentiation, the cell lines could be induced only to differentiate to a certain more mature stage, but could not be triggered to differentiate terminally with regard to expression of isoenzyme patterns.

Isoenzyme studies in human leukemia-lymphoma cell lines--V. Induction of differentiation by T-cell derived differentiation-inducing activity

A panel of human leukemia cell lines from various lineages (T-cell, pre B- and Non-T/Non-B cell, myelomonocytic and erythroleukemia cell lines) were utilised as model systems of the distant effects of differentiation-inducing activity (DIA) produced by the T-leukemia cell line HUT-102. DIA inhibited cell proliferation and induced distinct morphological changes which were more pronounced in the myelomonocytic and erythroleukemia cell lines than in the lymphoid cell lines. DIA triggered in the myelomonocytic and erythroleukemia cell lines an increase in the number of NBT-reducing cells and caused strong adherence to plastic surface. The T-cell lines showed aggregation of cells in floating clusters. In the isoenzyme analysis of the enzymes carboxylic esterase and acid phosphatase, it was found that DIA stimulated the new expression of isoenzymes and a stronger staining intensity of several isoenzyme bands in all cell lines, however, at varying degrees. HL-60 and HEL displayed newly a monocyte-specific isoenzyme. Several myelomonocytic and erythroleukemia cell lines were triggered to express the tartrate-resistant acid phosphatase isoenzyme. The cell kinetic, morphological, functional and isoenzymatic data demonstrated that DIA effected the development of the different blood cell types. However, it appears that the cells reached a new differentiation block after acquired expression of differentiation-linked features; the lymphoid cell lines were more limited in their response to DIA than the myeloid and erythroid cells.

Occurrence of particular isoenzymes in fresh and cultured leukemia-lymphoma cells. III. Esterase isoenzyme in monocytes

The expression of a particular alpha-naphthyl acetate esterase isoenzyme which is specific for monocytes was examined in a panel of cultured leukemia-lymphoma cell lines (n = 88), freshly obtained leukemia-lymphoma cells (n = 527), and in fresh (n = 10) and cultured (n = 22) leukemia cells treated with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). The sodium fluoride-sensitive isoenzyme was separated by isoelectric focusing on horizontal thin-layer polyacrylamide gels. The esterase isoenzyme was not detected in untreated or TPA-treated lymphoid, erythroid, or Hodgkin's disease-derived cell lines, but was seen in leukemia cell lines of monocytic origin. TPA induced the new expression of this marker isoenzyme in two leukemia cell lines of promyelocytic and erythroid origin that are known to differentiate along the monocytic-macrophage cell lineage; TPA stimulation increased the staining intensity of the band in monocytoid cell lines. This esterase isoenzyme was found in 92% of the cases classified morphologically as acute myelomonocytic or monocytic leukemia, but only in 3% of the non-monocytic acute myeloid leukemias. All lymphoid or erythroid leukemias or lymphomas were negative. Treatment with TPA of AML and CML cells, which commonly differentiate to monocyte/macrophage-like cells, showed de novo the monocyte-specific isoenzyme. It is concluded that this isoenzyme is a characteristic marker for monocytic leukemia cells and will be a useful tool for the discriminatory identification of the monocytic element in normal and leukemic cells.

Expression of FMC7 antigen and tartrate-resistant acid phosphatase isoenzyme in cases of B-lymphoproliferative diseases

A panel of different B-cell malignancies representing various stages of B-cell differentiation were analyzed for the expression of an antigen labeled by the monoclonal antibody FMC7 and of tartrate-resistant acid phosphatase (TracP) activity. The FMC7 antigen and TracP were not found on early immature pre B-cell proliferations, appeared at early and intermediate B-cell stages, reached their peak of expression in terms of both incidence of positivity and staining intensity at the late B cell stage (as represented by hairy cell leukemia) and were lost at the B-cell/plasma cell transition. Although detected at similar stages of B-cell differentiation, FMC7 and TracP appear to be independently expressed and were not related to a particular Ig class. The simultaneous detection of FMC7 and TracP represents a distinguishing parameter for the identification of hairy cell leukemia.

Occurrence of particular isoenzymes in fresh and cultured leukemia-lymphoma cells. II. Hexosaminidase I isoenzyme

The isoenzyme profiles of hexosaminidase (N-acetyl-beta-D-glucosaminidase) were analyzed by isoelectric focusing on horizontal polyacrylamide thin-layer gel with special emphasis on the intermediate isoenzyme (Hex I). The expression of Hex I was examined in 87 leukemia-lymphoma cell lines, in 14 B-lymphoblastoid cell lines, in 441 cases of leukemia-lymphoma (specimens containing 80% or more tumor cells), in 22 leukemia cell lines and in 14 cases of leukemia that had been treated with phorbolesters (TPA) for induction of differentiation, and in the mononuclear cell preparations separated from peripheral blood, lymph node, thymus, bone marrow, tonsil, liver, and spleen specimens from normal donors. Hex I was detected in the leukemia cell lines arrested at early, immature or at late, mature stages of B- and T-cell differentiation, but not in cell lines blocked at intermediate stages of maturation. Most myelomonocytic leukemia cell lines and the erythroleukemia cell lines showed Hex I, whereas the B-lymphoblastoid cell lines were negative for this marker. During induction of differentiation, the expression of Hex I was lost in 13 of 15 leukemia cell lines that were originally Hex I-positive. Among the panel of the "fresh" leukemia-lymphoma cells, Hex I was found predominantly in cases of acute lymphoblastic leukemia and acute myeloblastic/monoblastic leukemia, but rarely or not at all in the mature T-, B- or myeloid malignancies. However, two out of two cases of multiple myeloma were Hex I-positive, and the Hex I expression could be induced by TPA in three of six B-cell chronic lymphocytic leukemia cases. Chronic myelocytic leukemia cells remained Hex I-negative during induction of differentiation. Hex I-positivity was not detected in the cell preparations from normal tissues, and peripheral blood indicating that the normal cellular counterpart of the Hex I-positive tumor cells are present at only low percentages within the respective cell populations. It is suggested that Hex I is a marker of early lymphoid and myeloid hematopoiesis that is no longer expressed in intermediate stages of lymphoid differentiation and in later or terminal stages of myeloid differentiation, but that is again detectable in terminally differentiated B-cells. Further studies will focus on identification and isolation of normal Hex I-positive cells.

Induction of differentiation in chronic myelocytic leukaemia cells by the phorbolester TPA

The mononuclear peripheral blood cells from eight patients with chronic myelocytic leukaemia (CML) were incubated in cell suspension culture in the presence of the phorbolester 12-O-tetradecanoylphorbol 13-acetate (TPA). TPA caused the treated cells to adhere and to acquire morphological and functional features characteristic of macrophage-like cells. Using isoelectric focusing distinct changes in the isoenzyme profiles of carboxylic esterase, acid phosphatase, hexosaminidase and lactate dehydrogenase were detected in the TPA-exposed cells. Besides an increase in the number and staining intensity of isoenzymes of all enzymes, TPA triggered the new expression of a monocyte-specific esterase isoenzyme isoenzyme and of the tartrate-resistant acid phosphatase isoenzyme. The latter two isoenzymes represent further parameters of the monocyte/macrophage complex. The results indicate that immature leukaemic cells arrested along the granulocytic cell axis retain the ability to transform to macrophages.

Occurrence of particular isoenzymes in fresh and cultured leukemia-lymphoma cells. I. Tartrate-resistant acid phosphatase isoenzyme

The cells from 87 leukemia-lymphoma cell lines, 14 B-lymphoblastoid cell lines, 459 cases of leukemia-lymphoma, normal specimens, 22 leukemia-lymphoma cell lines treated with 12-O-tetradecanoylphorbol 13-acetate (TPA) and 14 cases of chronic lymphocytic leukemia (CLL) and chronic myelocytic leukemia (CML) treated with TPA were analyzed for the expression of tartrate-resistant acid phosphatase (TracP) isoenzyme separated by isoelectric focusing. The TracP isoenzyme was seen in the following leukemia-lymphoma cell lines: 4 of 30 T-cell, 2 of 35 B-cell, 1 of 6 non-T/non-B-cell, 1 of 8 myelomonocytic, 3 of 4 erythroleukemia, and 3 of 4 Hodgkin's disease-derived cell lines. The expression of the TracP band could be induced by treatment with TPA in 3 myelomonocytic leukemia cell lines. Among the different types of leukemia-lymphoma cells freshly obtained from patients, the TracP isoenzyme was detected at a high incidence in cases of B-CLL, hairy cell leukemia (HCL), and B-lymphoma. Of the myeloid leukemias, 10% to 20% displayed the TracP isoenzyme. TracP positivity was detected in the peripheral blood, tonsil, bone marrow, spleen, and liver obtained from healthy donors, but not in the thymus. The expression of the TracP band could be newly induced by TPA in cases of CLL and in cases of CML. It is concluded that TracP activity is not specific for HCL, but is found at high incidences in cases of HCL, B-CLL and B-lymphoma. The TracP isoenzyme is not expressed by very immature lymphoid leukemia cells, but by cells arrested at later stages of differentiation of the T- or B-cell lineage, and by some myeloid cells.

Induction of differentiation in the human leukemia cell line SPI-802: morphological, immunological, and isoenzymatic changes

The phorbolester 12-0-tetradecanoylphorbol 13-acetate (TPA) was used for the induction of differentiation in cells of the human leukemia cell line SPI-802. The cellular morphology, surface marker antigen expression, and isoenzyme profiles of four enzymes (carboxylic esterase, acid phosphatase, hexosaminidase, and lactate dehydrogenase) served as parameters for monitoring the induced phenotypical changes. TPA led to distinct alterations of the morphology and significantly affected the growth rate with cessation of cell proliferation. No major increase in the number of nitro blue tetrazolium-positive cells or aggregation of cells, phagocytosis of latex beads, adherence to plastic surface, or development of pseudopodia were observed. As TPA-treated SPI-802 cells remained negative for these markers of the monocyte-macrophage complex, it can be concluded that the cells did not differentiate into monocytes and macrophages. The immunological marker profile based on testing of 55 monoclonal antibodies, terminal deoxynucleotidyl transferase and two erythrocyte rosette tests indicated a differentiation of SPI-802 cells along the granulocytic cell lineage. This was confirmed by isoenzyme analysis, especially that of carboxylic esterase. An isoenzyme specific for monocytes and macrophages was not detected. In earlier studies it was found that SPI-802 cells produce hemoglobin upon exposure to TPA or hemin. This latter observation and the present results suggested a comparison with the two erythroleukemia cell lines K-562 and HEL. SPI-802 cells appear to have the potential to differentiate along several cell lineages.

Erythroleukemia cell lines HEL and K-562: changes in isoenzyme profiles and morphology during induction of differentiation

The effects of the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) and of hemin on the human erythroleukemia cell lines HEL and K-562 were studied using the parameters cellular morphology, cell proliferation, positivity in the nitro-blue tetrazolium (NBT)-reduction test, adherence to surface, development of pseudopodia, and isoenzyme profiles of carboxylic esterase, acid phosphatase, hexosaminidase and lactate dehydrogenase (LDH) separated by isoelectric focusing on horizontal polyacrylamide gels. TPA and hemin induced similar morphological changes in HEL and K-562, erythrocyte-like cells were seen to be the predominant population after exposure to hemin. Both TPA and hemin led to cessation of cell proliferation and to a dose-dependent decrease in the number of viable nucleated cells. Whereas HEL cells treated with TPA became positive in the NBT-reduction test, adhered to plastic surface and showed pseudopodia, HEL cells exposed to hemin and K-562 cells cultured with TPA or hemin did not show these markers indicative of the macrophage-cell lineage. TPA-treated HEL cells exhibited isoenzyme patterns which were characteristically seen in cells of the monocyte-macrophage complex. 'Myeloid isoenzyme profiles' were found in TPA-treated K-562 cells. As evidenced by the above described phenotypical changes, HEL cells appeared to differentiate along the macrophage and erythroid cell lineages. Induced K-562 cells displayed myeloid and erythrocytic markers.

Morphological and isoenzymatic differentiation of B-chronic lymphocytic leukaemia cells induced by phorbolester

Fresh leukaemia cells from the peripheral blood of 6 patients with B-chronic lymphocytic leukaemia (CLL) were cultured in the continuous presence of the phorbolester 12-O-tetradecanoylphorbol 13-acetate (TPA) for in vitro induction of differentiation. Upon treatment with TPA the cells showed distinct morphological changes consisting of cytoplasmic and nuclear enlargement, vacuolisation and protrusion of cytoplasm, eccentric location of nuclei with perinuclear clear zones, and oval to elongated cell forms. Isoenzyme profiles of the enzymes carboxylic esterase, acid phosphatase, hexosaminidase and lactate dehydrogenase (LDH) were analysed by isoelectric focusing on polyacrylamide gels. An increase in the number and in the staining intensity of isoenzymes were observed for all 4 enzymes in the TPA-exposed cells indicating a maturation along the B cell pathway. TPA triggered the new expression of the tartrate-resistant acid phosphatase isoenzyme, a marker of hairy cell leukaemia (HCL) cells, and of the hexosaminidase I isoenzyme, a marker of multiple myeloma cells. The induced phenotypic changes are suggestive of differentiation to stages corresponding to those of HCL cells or 'pre-plasma cells'.

Phenotyping of malignant hematopoietic cells. Analysis of 1200 cases of leukemia-lymphoma

1255 cases of leukemia-lymphoma were tested between 1972 and 1984 by multiple marker analysis. Routine leukemia phenotyping was performed using standard morphological and cytochemical techniques in combination with clinical and histo-pathological information; the main emphasis was put on immunological surface marker analysis using erythrocyte rosette assays, TdT and a large panel of poly- and monoclonal antibody tests. The 1255 cases were divided into these major types and subtypes: 349 cases of ALL and related immature T- and Burkitt-lymphomas (cALL, pre B-ALL, B-ALL and Burkitt-lymphomas, T-ALL and immature, mostly leukemic T-lymphomas, Null-ALL), 454 cases of mature T- and B-cell malignancies (T-CLL, mycosis fungoides, Sezary-syndrome, T-lymphomas, B-CLL, hairy cell leukemia, multiple myeloma, B-lymphomas), 263 cases of acute myeloid leukemias (AML, AMMoL/AMoL), 182 cases of chronic myeloid leukemias (CML in chronic phase, CMoL, CML in blast crisis), 6 cases of erythroleukemia and 1 case of megakaryoblastic leukemia. A simplified classification scheme which has been used in our laboratories is presented. Phenotyping is of diagnostic, prognostic and therapeutic relevance, most evidently for patients with ALL. Routine leukemia phenotyping should be performed with highly standardized techniques and reagents and by combining information from several fields in the multiple marker analysis. New areas of leukemia research might become very useful for the routine procedure of phenotyping.

Hodgkin's disease derived cell lines HDLM-2 and L-428: comparison of morphology, immunological and isoenzyme profiles

The cell lines HDLM-2 and L-428 were established from the pleural effusions of two patients with Hodgkin's disease. We studied and compared phenotypic characteristics of HDLM-2 and L-428 cells before and during induction of differentiation with 12-O-tetradecanoylphorbol 13-acetate (TPA) using a number of parameters. TPA-treated HDLM-2 and L-428 cultures did not show adhesion to plastic surface or aggregation of cells; the cells did not develop pseudopodia and were not phagocytic. Only a slight increase in the percentage of NBT-positive cells was observed for L-428 cells. TPA led to a cessation of cell proliferation and to a dose-dependent decrease in the number of viable cells in both cell lines. In HDLM-2 and L-428, treatment with TPA induced distinct morphological changes indicative of a partial differentiation along the myeloid cell lineage. In addition, the production and expellation of benzidine-positive, unnucleated particles were observed in HDLM-2 and L-428 cells. The induced isoenzyme profiles of carboxylic esterase and acid phosphatase resembled those found in myelomonocytic leukemia cell lines. Both cell lines were negative for immunological markers of the T- and B-cell lineages, but reacted with several markers associated with the myelomonocytic cell lineages. HDLM-2 cells produced a factor which could induce differentiation in 12 leukemia cell lines. The overall results suggest that Hodgkin and Sternberg-Reed cells constitute a unique cell type and might be derived from cells of the myelomonocytic cell lineage.

Reactivity pattern of 'myeloid monoclonal antibodies' with emphasis on MCS-2

The reactivity pattern of the murine monoclonal antibody (MoAb) MCS-2 was tested on a panel of 724 cases of leukemia-lymphoma. MCS-2 was positive in 178/185 (96%) cases of AML (FAB M1-3), 10/10 cases of AMMol/AMoL (FAB M4/5), 42/45 (93%) cases of CML, 1/1 case of CMoL, 37/38 (97%) cases of CML-myeloid blast crisis, 0/9 cases of CML-lymphoid blast crisis. No positive staining was seen in 238 cases of T-CLL, mycosis fungoides, Sèzary-syndrome, B-CLL, hairy cell leukemia, multiple myeloma and T- and B-lymphoma nor in 32 cases of B-ALL, Burkitt-lymphoma, Null-ALL and immature T-lymphoma. A positive expression was found in 8/110 cases of cALL, 1/6 cases of pre B-ALL and 1/35 cases of T-ALL. Fifteen other MoAbs (MCS-1, OKM1, My-1, Leu-M1, Leu-M3, CA-2-38, MY4, MY7, MY8, MY9, VIM-D2, VIM-D5, Mol, Mo2, 63D3) which are associated with the myelomonocytic cell lineages were tested by indirect immunofluorescence on 60 or more patients (62-149 cases). A wide variability in the frequency of positivity was seen for the panel of cases studied and for the blast cell populations per individual samples: 21-96% of the AML cases (FAB M1-3) and 31-100% of the AMMoL/AMoL cases (FAB M4/5) were positive for the various MoAbs. None of the analysed MoAbs stained only myelocytic or only monocytic leukemias, but a certain degree of preference for the monocytic variants was noted for Leu-M3, CA-2-38, MY4, VIM-D2, Mo2 and 63D3. The detection of MCS-2 on immature ALL blast cells might indicate a coexpression of lymphoid and myeloid markers on very immature cells, or an abnormal gene expression by malignant cells, or the identification of a so far undetected subclass of acute leukemias.

Expression of a monocyte-specific esterase isoenzyme in cases of acute myeloid leukemias

The carboxylic esterase (E.C. 3.1.1.1) isoenzymes from cases of acute myeloid leukemias were separated by analytical isoelectric focusing on horizontal thin-layer gels. One isoenzyme consisting of one or two components (bands) could be completely and selectively inhibited by addition of 40 mM sodium fluoride (NaF) to the staining bath. The 105 cases were classified into the groups M1-M6 according to the FAB proposals. The NaF-sensitive isoenzyme was not detected in cases of FAB groups M1/2 (acute myeloblastic leukemia without or with maturation), group M3 (acute promyelocytic leukemia) or group M6 (erythroleukemia). Thirty-one out of 33 cases in the FAB group M4 (acute myelomonocytic leukemia) and 9/9 cases in FAB group M5 (acute monocytic leukemia) expressed the NaF-sensitive isoenzyme. The NaF-sensitive isoenzyme was found at different staining intensities; all M5 cases showed the isoenzyme at strong or very strong intensity, whereas most of the M4 cases displayed the isoenzyme at weak, medium or strong staining intensity. The data presented are further evidence that the presence of the NaF-sensitive esterase isoenzyme indicates monocytic involvement or differentiation in cases of myeloid leukemias. The easy and fast to perform method of isoelectric focusing can be used to distinguish the monocytic variants among the acute myeloid leukemias and can supplement the morphological analysis of these cases.

Isoenzyme studies in human leukemia-lymphoma cell lines--IV. Lactate dehydrogenase

Isoelectric focusing (IEF) in horizontal polyacrylamide gels has been used to separate lactate dehydrogenase (LDH) isoenzymes in 97 human permanent hematopoietic cell lines (85 leukemia-lymphoma cell lines and 12 'normal' B-lymphoblastoid cell lines). Maximally 8 LDH bands were seen; the electrophoretically detectable bands 4 and 5 could be separated by IEF into 2 and 3 isoenzymes, respectively. The LDH patterns have been found to vary both in number of isoenzymes and in relative intensity in different cell lines depending upon the stage at which arrest of differentiation occurred. These differences can be used to analyse and distinguish different cell lines. The method should provide a valuable supplement to the enzymatic phenotyping and complete characterization of fresh and cultured leukemias and for the monitoring of phenotypic changes occurring during induction of differentiation.

High concordance between marker profiles of 22 human leukemia-lymphoma cell lines tested with the same monoclonal antibodies before and during the second international workshop on human differentiation antigens

Our laboratory participated in the Second International Workshop and Conference on Human Leucocyte Differentiation Antigens. In this international study the reactivity profiles of monoclonal antibodies were analyzed on normal and malignant hematopoietic cells. The Workshop was divided into three categories: the T-cell, B-cell and myelomonocytic cell studies. We blindly tested 159 coded monoclonal antibodies of the panel for the T-cell study on 22 permanently established leukemia cell lines. The monoclonal antibodies were provided by the Workshop Committee and their reactivity with the target cells was visualized by standardized indirect immunofluorescence. After decoding it was recognized that 11 monoclonal antibodies had been examined on these cell lines prior to the Workshop. The reactivity of these 11 monoclonal antibodies was analyzed and compared with the earlier results. From a total of 217 paired tests done blindly in the Workshop study and prior to the Workshop, 191 tests (88%) did not show significantly different data. The possible reasons for discrepancies include nonspecific Fc-receptor-binding on some cell lines and a relatively nonspecific reactivity of some monoclonal antibodies. This analysis demonstrates the stability of the antigen expression on human leukemia-lymphoma cell lines grown at consistently optimal conditions, for the tests, using the same monoclonal antibodies as in the Workshop, had been performed 0.5-5 years prior to the Workshop study. On the other hand, nonspecific Fc-binding, wide "specificity" of monoclonal antibodies and a shift in antigen expression of the cells (due to poor growth conditions, involuntary induction of differentiation and other factors) must be taken into consideration upon immunological analysis.

Isoenzyme studies in human leukemia-lymphoma cell lines--III. beta-Hexosaminidase (E.C. 3.2.1.30)

The hexosaminidase (beta-N-acetylglucosaminidase) isoenzyme profiles of 86 human hematopoietic cell lines grown actively in suspension culture were analysed by isoelectric focusing and by conventional disc electrophoresis on horizontal thin-layer polyacrylamide gels. A maximum of three hexosaminidase (Hex) isoenzymes (A = anodic, I = intermediate, B = basic) could be demonstrated. The immunological phenotyping of 74 leukemia-lymphoma derived cell lines had led to a categorization into four groups with a subclassification of the T- and B-cell lines into several stages of differentiation: 26 T-cell, 34 B-cell, 6 myelomonocytic and 8 Non-T, Non-B cell leukemia-lymphoma cell lines. Twelve so-called 'normal' B-lymphoblastoid cell lines were also available. Distinct isoenzyme profiles were seen in the different stages of differentiation in the T- and B-leukemia-lymphoma cell lines. Among the 12 normal B-lymphoblastoid cell lines heterogeneity in the isoenzymatic phenotypes was detected. Hex isoenzyme expression in normal and neoplastic lymphoid cell lines represents hypothetically sequential stages of T- and B-cell differentiation. Myelomonocytic cell lines displayed strongly stained bands of all three isoenzymes. Heterogeneity was seen in the group of Non-T, Non-B cell lines. Four out of 5 pre B-cell lines and 4 out of 4 Non-T, Non-B cell lines which are comparable to cases of pre B- and common ALL revealed a high Hex I/Hex A ratio in terms of intensity of the isoenzyme bands. The analysis of Hex isoenzymes is useful for characterizing lymphoid and myeloid populations (both normal and malignant, cultured or fresh), particularly with regard to their stage of differentiation. But this enzyme should be part of a multiple enzyme study where the information obtained is complementary. In turn, enzyme marker analysis should be included in the multiple marker analysis for an optimized characterization of leukemic cells.

Isoenzyme studies in human leukemia-lymphoma cells lines--II. Acid phosphatase

This report describes the qualitative acid phosphatase (acP) isoenzyme profiles detected in permanent human hematopoietic cell lines. The acP activity was separated into its isoenzymes by isoelectric focusing on horizontal thin-layer polyacrylamide gels. The pattern of acP isoenzyme was investigated in a total of 86 cell lines. These cell lines were classified into five groups on the basis of their phenotypes characterized in the multiple marker analysis: 74 leukemia-lymphoma cell lines (26 T-, 34 B-, 6 myelomonocytic, 8 Non-T, Non-B cell lines) and 12 so-called 'normal' Epstein-Barr virus transformed B-lymphoblastoid cell lines. Their immunological features had been analysed in detail by use of a large panel of poly- and monoclonal antibodies which led to a further subclassification into stages of differentiation. A progressive increase in number and staining intensity of the isoenzymes which paralleled the expression of surface markers at different stages of differentiation along their developmental pathway was seen in the T- and B-leukemia-lymphoma cell lines. Some cell lines whose isoenzyme profiles did not correspond to the stage of differentiation as evidenced by surface antigen analysis might represent good examples of deranged gene expression in otherwise normally programmed malignant cells, i.e. in our study a mismatch between the isoenzymatic and immunological phenotypes. The tartrate-resistant isoenzyme was detected in 9 out of 74 leukemia-lymphoma cell lines (4 T-, 2 B-, 1 myelomonocytic, 2 Non-T, Non-B cell lines) and in 10 out of 12 normal B-lymphoblastoid cell lines; the only one studied hairy cell leukemia cell line did not express this isoenzyme. The relative specificity of the tartrate-resistant acP is discussed in detail. No leukemia-lymphoma specific isoenzyme or an additional isoenzyme which was not seen in normal hematopoietic cells could be observed. Nor did we find an isoenzyme or isoenzyme pattern characteristic for a certain cell lineage. This underlines the necessity of a combined analysis using markers from different disciplines in the 'multiple marker analysis' in order to accurately characterize normal and malignant blood cells. Furthermore, our results support the concept of maturation arrest at particular stages of differentiation together with the theory of normal gene expression in leukemic cells equivalent to that in their normal counterparts.