Continuous culture of seven new cell lines (SK-L1 to 7) from patients with acute leukemia

Serial Transplantation of a Human Acute T Lymphoblastic Leukemia into Nude Mice

A human acute T lymphoblastic leukemia line (PF-382) was serially transplanted into nude mice. No takes were observed in untreated nude mice, whereas solid tumors were observed in splenectomized and total body, sublethally irradiated mice. The minimal tumor-inducing dose and the latency time remained unchanged after the third and fifth serial transplants. Moreover, leukemic cells recovered from the 8th in vivo passages displayed the same differentiation antigens and chromosomal markers as the in vitro PF-382 cell line used for the first transplant. This stable and well-characterized experimental system could be a new model for T-lymphocyte differentiation and immune-reactivity against human leukemias.

Acute leukaemia: development, remission/relapse pattern, relationship between normal and leukaemic haemopoiesis, and the 'sleeper-to-feeder' stem cell hypothesis

Attention has been focused on two problems of acute leukaemia: (1) the origin of normal-appearing haemopoietic cells during relapse, and (2) the inverse relationship between leukaemic blast cell proliferation and useful haemopoietic cell production. The available evidence suggests that the normal-appearing cells during relapse may not all be remnants of normal haemopoiesis but may at least in part be derived from leukaemic cells. Although a differentiation defect is a major characteristic of acute leukaemia, it seems as if this defect is not absolute: some cells may succeed in differentiating more or less normally in spite of their descent from a leukaemic stem cell. Acute leukaemia is usually considered to be a primary white cell disorder which indirectly affects the other haemopoietic cell lines. It appears more likely, however, that acute leukaemia, at least the myeloid type, is a disorder of a stem cell common to granulocytopoiesis, erythropoiesis, and probably thrombocytopoiesis. Most descendants from the diseased stem cell fail to differentiate and remain at the blast cell level where they proliferate for some time; however, at a certain point proliferation ceases and the cells ultimately die. Another fraction of the progeny of the leukaemic stem cells may differentiate to some extent and may give rise to functionally useful cells. This is analogous to chronic myeloid leukaemia. The mechanism by which useful haemopoiesis apparently is suppressed in the presence of leukaemic blast cells has remained enigmatic so far. Previously suggested explanations which all assume some kind of cell-cell interaction by which normal haemopoietic cells succumb have neither been proved nor disproved. In this chapter, a new hypothesis is presented. It is assumed that some normal haemopoietic stem cells enter a dormant state at various distances in lineage from the fertilized ovum ('sleepers'). Another fraction of haemopoietic stem cells ('feeders') are actively proliferating and serve to feed the differentiating haemopoietic cell lines and to maintain the 'feeder' pool. When the 'feeder' pool is exhausted, a 'sleeper' cell is activated and sets up a new 'feeder' clone. Otherwise, 'sleepers' are protected against acting as 'feeders' in order to keep 'sleeper' divisions at a minimum and thus preserve their genetic information as intact as possible. It is suggested that the leukaemic event initially takes place in one or a few 'sleepers'. If the leukaemic 'sleeper' never succeeds in setting up a 'feeder' clone, clinical leukaemia will not develop. Clinical leukaemia will result if a leukaemic 'sleeper' establishes a leukaemic 'feeder' pool.(ABSTRACT TRUNCATED AT 400 WORDS)

Thymidylate synthase inhibition in cells with arrested DNA synthesis is not due to an allosteric interaction in the replitase complex

Activity of thymidylate synthase was measured in situ in leukemia cells by tritium release from [5-3H]dUrd. Aphidicolin, an inhibitor of DNA polymerase alpha, but not thymidylate synthase, caused a time dependent inhibition of the enzyme when added to the cells after [5-3H]dUrd. Cells treated with hydroxyurea and aphidicolin in sequence before addition of [5-3H]dUrd had a high initial thymidylate synthase activity that decreased with time. This pattern indicates that thymidylate synthase activity is linked to DNA synthesis; however, its inhibition by drugs that inhibit DNA synthesis may be due to accumulation of thymidine nucleotide(s), rather than to an allosteric interaction in the replitase complex.

Leu-10 (HLA-DC/DS) antigen distribution in human leukaemic disorders as detected by a monoclonal antibody: correlation with HLA-DR expression

Reactivity of the monoclonal antibody anti-Leu-10 that detects the human equivalent of the murine 1-A subregion antigen(s) was studied and correlated with anti-HLA-DR expression on 83 cases of acute and chronic leukaemias, leukaemic non-Hodgkin's lymphomas (NHL) and seven human cell lines. Peripheral blood and/or bone marrow leukaemic cell suspensions were stained by indirect immunofluorescence for both monoclonal antibodies and analysed by flow cytometry. Leu-10, like HLA-DR, was absent from T-cell acute lymphoblastic leukaemia (ALL) (two cases). It was expressed on: 33% of TdT +, CALLA + ALL cases (8/24); 27% (4/15) of acute non-lymphocytic leukaemia (ANLL); 85% (24/28) of HLA-DR + B-cell chronic lymphocytic leukaemia (CLL); and on 9/14 (64%) B-cell NHL cases. There were no differences in clinical characteristics between Leu-10 + and Leu-10--patient subgroups. We were able to induce Leu-10 expression on 'Josh' cell line by culturing it with 12-0-tetra-decanoylphorbol-13-acetate (TPA). Our data indicate that Leu-10 expression on leukaemic cells is more restricted than HLA-DR and is likely to be differentiation related, since it can be induced to be expressed at a later stage than HLA-DR.

Rearrangement in rDNA-bearing chromosomes in cell lines from neoplastic cells

Cytological hybridization in situ and karyotypic analysis have been used to investigate positional changes in rDNA, and morphological changes in rDNA-bearing chromosomes, in a series of cell lines established from patients with various proliferative disorders. Characteristic features of chromosomes in these cell lines include extreme differences in the number of rRNA genes per locus, translocations involving rDNA, and distinct rearrangements of a large portion of the rDNA complex to a q-terminal position on acrocentric chromosomes.

Inaccuracy of estimations of s phase fraction by reduction in cloning efficiency with hydroxyurea or tritiated thymidine

The current hypothesis, that the fractional reduction of cloning efficiency in semi-solid culture systems induced by pretreatment of the cells with hydroxyurea (HU) or [3H]TdR equals the fraction of cells initially in S phase, is tested. A lymphoblastoid cell line, SK-L7, with known cell cycle kinetics was exposed to cytotoxic concentrations of HU or suicidal doses of [3H]TdR and then initiated in semi-solid and liquid culture. Although approximately 0.6 of the initial population was in S, 1-hr exposures of HU at concentrations of up to 10(-2) M failed to reduce subsequent cloning efficiency. The 1-hr exposure to HU did not reduce either the immediate cell number or the gross population doubling rate over 24 hr. A 24-hr exposure to 10(-3) M HU reduced the cloning efficiency by approximately 98%, confirming the drug's cytotoxic capability. [3H]TdR at doses of 100 microCi/ml for 20--40 min reduced the cloning efficiency by approximately 60 and 70%, respectively. Although no cytotoxicity immediately after exposure was observed in either case, gross population doubling rate in liquid culture was reduced. While HU failed to reduce subsequent cloning efficiency, [3H]TdR reduced cloning efficiency by approximately the fraction of initial cells in S. The above hypothesis, therefore, cannot be applied naïvely as a technique for quantitating the fraction of a clonogenic cell population in S phase.

Cloning of fresh lymphoma cells

We attempted to induce in vivo clonal growth of neoplastic lymphoid cells from fresh specimens of involved tissue from 22 patients with no-Hodgkin lymphoma (NHL). Conditioned media derived from two human B-lymphocyte tissue culture lines were tested for their ability to promote colony growth. In addition, we compared the incidence of colony induction to the flash-3H-thymidine labeling index (LI) of the cells in the tissues cultured. Successful colony induction occurred in three-tenths of the cases of diffuse histiocytic lymphoma and one-half of the cases of nodular lymphoma. Cloning efficiencies were low, ranging from 0.0003 to 0.04%. There was no apparent relationship between successful instances of cloning and LI. We have confirmed the observations of Jones et al that lymphoid tumor cells can be cloned from tissues involved by NHL using a soft agar system. The possibility of using such systems for clinical predictive assays of chemotherapeutic drug toxicity toward tumor cells of NHL is discussed. We conclude that further refinements of the assays are desirable before they can be applied to widespread clinical use.

Differences in genetic stability between human cell lines from patients with and without lymphoreticular malignancy

Isoenzymes determined by 11 loci have been examined in 137 human lymphoblastoid lines of various origins with a view to determining their phenotypic stability in culture. Lines of normal origin are stable and at these loci are phenotypically identical to the individuals from whom they are derived. Lymphomas and some lines from patients with leukaemias show a tendency to increased apparent homozygosity, presumably resulting from loss of expression of one or other allele during culture. Taken together with the cytogenetic evidence this suggests that progressive loss of functional parts of the genome with time in culture is a characteristic of lines derived from malignant lymphoid cells.

Abortive expression of the Epstein-Barr virus (EBV) cycle in a variety of EBV DNA-containing cell lines, as reflected by nucleic acid hybridization in situ

A variety of Epstein-Barr virus (EBV) DNA-containing cell lines have been tested for the expression of the EBV-associated antigens EBNA (nuclear antigen), EA (early antigen), and VCA (viral capsid antigen), and for the presence of cells containing disproportionate amounts of EBV DNA. The antigen tests utilized immunofluorescence and 125I-labelled antibodies combined with autoradiography. EBV-DNA was detected by in situ hybridization with 3H-labelled EBV RNA complementary to P3HR-1 EBV DNA (P-EBVcRNA). The P-EBVcRNA has been shown to represent the majority of the P3HR-1 EBV DNA sequences. It was concluded that EBV DNA-containing cell lines can be divided into those that express only EBNA, those that express EBNA and EA and those that express EBNA, EA and VCA and also contain cells that undergo disproportionate EBV DNA synthesis. Consequently, in some cell lines there is an abortive expression of the EBV cycle in that some cells spontaneously express EA but fail to continue further to viral DNA synthesis. A similar pattern can be found after experimental induction of the EBV cycle, suggesting that related mechanisms govern the spontaneous expression of the EBV cycle and the extent of its inducibility.

The establishment of the suspension Epstein-Barr virus producing cell lines from patients with tumoral diseases

Isolation of the Epstein-Barr virus (EBV) in suspension lymphoblastoid cell lines from human patients with tumor diseases, mainly malignant lymphoma, has been described. It has been shown that the EBV was isolated from human patients with myeloid type of leukemia in 75% of cases. A similar virus was also isolated from patients with Hodgkin's disease and leukemoid reaction of the myeloid type for lung cancer. Morphological, cytochemical, immunological, and cytogenetic characteristics of the cell lines in which the EBV is replicated have been investigated.

Detection of Epstein-Barr virus (EBV) DNA sequences using in situ hybridization

In situ hybridization was used to detect Epstein-Barr virus (EBV) DNA sequences under conditions where the virus DNA is replicating spontaneously and where it is induced to do so following superinfection. The in situ reaction itself is influenced by several parameters, analogous to conventional nucleic acid hybridization, consideration of which should help to optimize the designing of in situ hybridization reactions in general. Both EBV complementary RNA (cRNA) and EBV DNA synthesized in vitro can efficiently detect the virus DNA sequences in situ. The findings presented here can therefore be utilized in both the study of EBV-cell interactions and, more generally, in studies using in situ hybridization as a general approach.

Acute myelogenous leukemia: a human cell line responsive to colony-stimulating activity

A permanent human cell line that maintains the granulocytic characteristics of acute myelogenous leukemia cells has been established. The cells of this line form myeloid colonies in soft gel culture in the presence of human colony-stimulating activity. The cell line may be useful for studying human acute myelogenous leukemia and the mechanism of response to colony-stimulating activity.

Sensitivity of various human lymphoblastoid cells to the antiviral and anticellular activity of human leukocyte interferon

Of eight lymphoblastoid cell lines studied five were insensitive to both the anticellular and antiviral activities of human leukocyte interferon, and two were sensitive to both activities. One line could not be fully evaluated since it was not possible to study its sensitivity to the antiviral activity.

Motility of L 5222 rat leukemia cells in the flattened state. Evidence against emperipolesis

Emperipolesis is the term for the assumed penetration of living cells into other living cells. As reported earlier, L 5222 rat leukemia cells, migrating in vitro, change from a spherical to a spread configuration when they meet flat cells, and continue to move in this shape within the contours of the target cells. Whether or not this close cellular association corresponded to emperipolesis could not be determined with phase and interference contrast cinemicrography alone. In combination with transmission electron microscopy, it could be demonstrated that the compartment, in which the spread leukemia cells move, is not the cytoplasm of the target cells, but the narrow space created by the target cells and the underlying glass surface. Thus, emperipolesis could be ruled out for L 5222 leukemia cells. On this basis the reported observations on emperipolesis are reviewed, and a critical attitude regarding the occurrence of emperiopolesis in general is advocated.

Increase of proliferative activity of leukaemic blast cells from human peripheral blood in liquid culture

The proliferative behaviour of leukaemic cells from the peripheral blood of 12 patients suffering from acute leukaemia was investigated in short term liquid culture. In 3 cases of AML an increase of the blast cell number was observed exceeding the initial value whereas in 9 other cases the cell number decreased more or less rapidly. In 9 of these patients the proliferation kinetics of the cultured leukaemic blast cells were studied with 3H-thymidine labelling. In all these cases the labelling index increased during the first days of culture, in 3 cases to values of 48%, 45% and 38% on day 3. Only in 5 cases, however, did an absolute increase of the blast cells incorporating 3H-thymidine occur. Here the doubling times of the proliferating leukaemic blast cells were estimated to be 12, 13, 14, 28 and 55 h. Since a doubling time of 12 to 14 h seems to be too short to be explained only by an exponential growth of the initially proliferating cells it is postulated that leukaemic blast cells in a G0- or long G1-phase were present in the peripheral blood of these patients and that these entered the cell cycle during liquid culture.

Cell surface antigens of human malignant melanoma: mixed hemadsorption assays for humoral immunity to cultured autologous melanoma cells

We studied how frequently patients with malignant melanoma have specific antibody to cell surface antigens of cultured autologous melanoma cells as demonstrated by mixed hemadsorption assays. Of 35 patients studied over periods ranging from 1 to 36 months with Stage II, III, and IV disease, two showed consistent and high titered reactivity against autologous melanoma cells, two showed less consistent and intermediate reactivity, seven showed sporatic, low titered reactivity, and the remainder were consistently negative. A detailed analysis was carried out with the sera of one patient with sufficiently high titer against autologous melanoma cells. By direct tests and by absorption analysis with a variety of melanoma and nonmelanoma cell lines which included autologous fibroblasts, the antigen could not be demonstrated on any cell type other than the autologous melanoma.

Characteristics of hematopoietic cell line established from human myelomonocytic leukemia

The peripheral blood of an acute myelomonocytic leukemia patient has been cultured for 16 months. The culture is at present at the 140th population doupling level. The cultured cells have the characteristics of so-called lymphoblastoid cells and proliferate actively as individual cells in small clusters, or in large clumps consisting of large mononuclear cells. Some of these cells appeare to be lymphoid, but the majority are immature mononuclear cells with a tendency to lobulate. They gave a weakly positive peroxidase reaction at the beginning of cultivation, and have given a strongly positive esterase reaction persistently. The cytoplasm shows ciliary or tail-like projections as the cell matures. Complement (C3) receptor and IgG receptors are found on the cell surface, and active phagocytosis is mannifest. Colloidal iron particles or viable red blood cells attached to the cell membrane suggesting possible differentiation to reticulum cells or macrophages. The cultured cells are mostly diploid but some cells show chromosome abnormality. Herpes type virus was foun in the nucleus, cytoplasma and on the cell membrane. The transplanatation of cultured cells to the cheek pouch of hamsters produced small tumors with histological findings resembling reticulum cell sarcoma.

Surface markers on human B and T lymphocytes. VIII. Association between complement and Epstein-Barr virus receptors on human lymphoid cells

An association has been found between the Epstein-Barr virus (EBV) and complement (C3d) receptors on human lymphoid cells. The evidence was four-fold: there was a correlation between the expression of these two receptors; inhibition experiments showed that the binding sites probably are close to each other in the cell membrane, although not identical; EBV and complement receptors have been found to co-cap in either order; and lymphoid cell lines lacking complement receptors could not be superinfected with EBV.

Motility of l5222 rat leukemia cells

The locomotive behavior of cells of the transplantable rat leukemia L5222 was studied by means of microcinematography. It was found that these cells exhibit a homogeneous pattern of movement resembling that of normal lymphoblasts and stimulated lymphocytes. This is in contrast to cytochemical and ultrastructural evidence according to which the cells are completely undifferentiated. Another phenomenon, recorded by timelapse, is the ability of the cells to move in a spherical and in a flattened state. Treatment with cytochalasin B in a concentration of 30mug/ml leads to loss of locomotion. Incubation with colchicine, 40mug/ml, results in a greatly reduced locomotion, while the on-spot motility is not impaired. The suitability of this model for investigations on the role of locomotion in penetration and tumor cell dissemination is emphasized.

Cell kill kinetics with hydroxyurea

The effects of various concentrations of hydroxyurea (HU) on a human lymphoid cell line in exponential growth phase have been studied using a combination of methods, including determination of the total and viable cell counts; the cells relative DNA content, measured in a flow microfluorimeter after staining with a fluorescent Feulgen technique; the mitotic index; and the percentage of cells incorporating thymidine-3H (TdR-3H) during brief and continuous exposure to the isotope both in the presence and absence of colcemid. A significant redistribution of the cells in the various phases of the cell cycle occurred during the first 24 hr of continuous treatment with 10(-3) M and 10(-2) M HU as follows: (1) division of cells in G2; (2) depletion of mid and late S phase cells due to early cell death; (3) movement of most G1 cells at a normal rate into early S phase where they accumulate; and (4) arrest of the remaining cells in G1, which represented the surviving population after treatment for 96 hr or longer. After removal of the drug, the cell fraction blocked in early S phase progressed semisynchronously through S, but many of the cells were unable to complete division. Their capacity to recover depended on the drug concentration and duration of exposure, but in general the cellular injury caused by HU was more reversible than that caused by "equivalent" concentrations of arabinosylcytosine.

Cytochemical and cytogenetic findings in five human leukocyte long-term cultures (LAHL) of different origin

Five human leukocyte long-term suspension cultures were investigated by means of cytochemical and cytogenetic methods. A striking resemblance in the morphology of these cells originating either from peripheral blood or from spleen of patients with or without hematological disorders was found. Lymphocytic origin of all five cultures is suspected. In the three cultures a diploid karyotype was found with some aberrations. In one culture, derived from the spleen of a patient with panmyelopathy the mosaic 45 XX C -/46 XX was detected. Anomalies of C group chromosomes were the most consistent type of chromosome aberrations in two lines. Both were EBV positive.

Hemoglobin synthesis in murine virus-induced leukemic cells in vitro: stimulation of erythroid differentiation by dimethyl sulfoxide

Cells of a cloned line of murine virus-induced erythroleukemia were stimulated to differentiate along the erythroid pathway by dimethyl sulfoxide at concentrations that did not inhibit growth. A rise in the number of benzidine-positive normoblasts was accompanied by increased synthesis of heme and hemoglobin and a decrease in the malignancy of the cells. This action of dimethyl sulfoxide, which was reversible, may represent the derepression of leukemic cells to permit their maturation.