Establishment and characterization of a human histiocytic lymphoma cell line (U-937)

A human hematopoietic cell line (U-937) with exceptional characteristics was derived from a patient with generalized histiocytic lymphoma. The morphology of the cell line was identical to that of the tumor cells in the pleural effusion from which the line was derived. Since Epstein-Barr virus (EBV) carrying diploid lymphoblastoid cell lines unrelated to the tumor population often become established in vitro from non-Burkitt lymphoma explants, several parameters were studied to discriminate the U-937 from such lines: morphology in vitro, growth characteristics, cytochemistry, surface receptor pattern, Ig production, lysozyme production, beta2-microglobulin production, presence of EBV genome and karyotype. In all these respects U-937 differed from prototype lymphoblastoid cell lines. The histiocytic origin of the cell line was shown by its capacity for lysozyme production and the strong esterase activity (naphtol AS-D acetate esterase inhibited by NaF) of the cells. It is therefore concluded that the U-937 is a neoplastic, histiocytic cell line.

The orphan receptor GPR55 is a novel cannabinoid receptor

BACKGROUND

The endocannabinoid system functions through two well characterized receptor systems, the CB1 and CB2 receptors. Work by a number of groups in recent years has provided evidence that the system is more complicated and additional receptor types should exist to explain ligand activity in a number of physiological processes.

EXPERIMENTAL APPROACH

Cells transfected with the human cDNA for GPR55 were tested for their ability to bind and to mediate GTPgammaS binding by cannabinoid ligands. Using an antibody and peptide blocking approach, the nature of the G-protein coupling was determined and further demonstrated by measuring activity of downstream signalling pathways.

KEY RESULTS

We demonstrate that GPR55 binds to and is activated by the cannabinoid ligand CP55940. In addition endocannabinoids including anandamide and virodhamine activate GTPgammaS binding via GPR55 with nM potencies. Ligands such as cannabidiol and abnormal cannabidiol which exhibit no CB1 or CB2 activity and are believed to function at a novel cannabinoid receptor, also showed activity at GPR55. GPR55 couples to Galpha13 and can mediate activation of rhoA, cdc42 and rac1.

CONCLUSIONS

These data suggest that GPR55 is a novel cannabinoid receptor, and its ligand profile with respect to CB1 and CB2 described here will permit delineation of its physiological function(s).

Characteristic chromosomal abnormalities in biopsies and lymphoid-cell lines from patients with Burkitt and non-Burkitt lymphomas

The karyotypes of cells from 10 Burkitt lymphoma (BL) biopsies, eight cell lines established from BL and nine cell lines from non-BL sources were studied by chromosome banding techniques. With the exception of the BL-derived cell lines BJAB, GC-BJAB, Maku and U-8691 all biopsies and lines of Burkitt origin contained an extra band at the distal region of the long arm of one chromosome 14. An extra band on chromosome 14 was also found in cells of one non-BL biopsy, in cells from a lymphosarcoma-derived cell line and in a long-established cell line derived from the pleural exudate of a patient with Hodgkin's disease. A distal region at the long arm of one chromosome 8 was missing in all metaphase figures of good technical quality in the same material. The size, morphology and stain-ability of the missing region corresponded fairly well to the extra region at chromosome 14. We therefore suggest that the chromosome 14 marker represents a translocation between chromosomes 8 and 14,t (8q-; 14q+). The translocation was present neither in lymphocytes of the peripheral blood of five Burkitt patients nor in five lymphoblastoid cell lines of non-BL origin. Trisomy 7 was found in two of the 10 BL biopsies, in two BL-derived cell lines, in one non-BL biopsy, in two lymphosarcoma-derived cell lines and in one cell line derived from a patient with Hodgkin's disease.

K562--a human erythroleukemic cell line

We have studied the surface membrane properties of the human leukemic cell line K562 which previously has been reported to represent an early stage of granulocyte maturation. The surface glycoprotein pattern of the K562 cells obtained after galactose oxidase-NaB[3H]4 labelling and slab gel electrophoresis shows striking similarities with that of normal erythrocytes but is completely different from the patterns of normal and malignant cells of various stages of the myeloblast to granulocyte differentiation. Moreover, the K562 cell expressed the major red cell sialoglycoprotein, glycophorin, on its surface as shown by immunofluorescence and by immunoprecipitation from labelled membrane preparations. As glycophorin is exclusively found on erythroid cells in human bone marrow we conclude that the K562 is a human erythroleukemic line.

Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303

Microquasars are binary star systems with relativistic radio-emitting jets. They are potential sources of cosmic rays and can be used to elucidate the physics of relativistic jets. We report the detection of variable gamma-ray emission above 100 gigaelectron volts from the microquasar LS I 61 + 303. Six orbital cycles were recorded. Several detections occur at a similar orbital phase, which suggests that the emission is periodic. The strongest gamma-ray emission is not observed when the two stars are closest to one another, implying a strong orbital modulation of the emission or absorption processes.

Lysozyme synthesis by established human and murine histiocytic lymphoma cell lines

A human cell line established in culture from a histiocytic lymphoma patient synthesizes and secretes the monocyte-granulocyte specific enzyme lysozyme. 18 other human cell lines with characteristics of T-lymphocyte, B-lymphocyte, Burkitt's lymphoma, non-Burkitt's lymphoma, myeloma, and bone marrow epithelial cells were not associated with lysozyme. Among murine cell lines, lysozyme was produced by (a) three histiocytic lymphoma or macrophage lines, which mediate antibody-dependent phagocytosis and cytolysis; (b) myelomonocytic leukemia line which also secretes myeloid colony-stimulating factor; and (c) a spontaneous lymphoma and an Abelson leukemia virus-induced lymphoma. Lysozyme-negative lines include another Abelson lymphoma, myelomas, T lymphomas, and mastocytoma.

Classification and biological nature of established human hematopoietic cell lines

Over 200 established human hematopoietic cell lines of normal and malignant origin have been investigated by morphological and functional parameters. Employing morphology as the overriding parameter four types of lines were identified. (1) Lymphoblastoid cell lines, derived from normal and neoplastic hematopoietic tissue, were characterized by the wide morphologic flexibility of individual lymphoblastoid cells, constant association with Epstein-Barr virus (EBV), polyclonal derivation, differentiation for immunoglobulin production (secretion) and their diploids. (2) Lymphoma cell lines. This type of line was established at a high frequency from Burkitt's lymphoma and rarely from other types of lymphoma, but never from patients without malignancy or with non-lymphoma malignancies. Important characteristics were morphologic stereotypia within each line, monoclonal derivation, common but not obligatory association with EBV, variability in the expression of Ig synthesis (no production, or membrane bound Ig, or secretion) and aneuploidy. (3) Myeloma cell lines could only rarely be obtained from patients with myeloma. The basis for classification of these lines is their production of Ig identical to the myeloma protein in vitro. Other important distinguishing features were: plasma cell morphology, absence of EBV and aneuploidy. (4) The leukemia cell line (MOLT 4) was the only line with T-cell characteristics and was easily distinguished from the other types. Important characteristics were a typical surface ultrastructure, absence of EBV and absence of immunoglobulin production, Individual lymphoblastoid lines were in principle identical whereas each line of the other three types had its own characteristic profile. The phenotypic characteristics of the lymphoblastoid lines were very stable during prolonged serial cultivation. Only in a few cases were secondary chromosomal, functional or morphologic alterations noted. We conclude that EBV-carrying lymphoblastoid lines can be obtained from non-neoplastic precursor cells from healthy as well as from diseased individuals. Lymphoma, myeloma and leukemia lines are only obtained from the respective neoplastic tissue but generally at a low frequency. With the exception of Burkitt's lymphoma, malignant hematopoietic tissue and leukemia frequently give rise to established cell lines in vitro of the lymphoblastoid type rather than lines derived from the neoplastic cells;

Continuous lymphoid cell lines with characteristics of B cells (bone-marrow-derived), lacking the Epstein-Barr virus genome and derived from three human lymphomas

Three exceptional cell lines have been tested for the presence of the Epstein-Barr virus genome by nucleic acid hybridization (complementary RNA.DNA) and Epstein-Barr virus-determined nuclear antigen tests. Two lines were derived from Swedish lymphoma cases and one from an African Burkitt-like lymphoma biopsy that was negative for Epstein-Barr virus DNA and the virus-determined nuclear antigen. All three lines apparently lacked the viral genome. Two of the three lines clearly had characteristics of B-cells (bone-marrow-derived).

High frequency of multiple melanomas and breast and pancreas carcinomas in CDKN2A mutation-positive melanoma families

BACKGROUND

: Inherited mutations in the CDKN2A tumor suppressor gene, which encodes the p16(INK4a) protein, and in the cyclin-dependent kinase 4 (CDK4) gene confer susceptibility to cutaneous malignant melanoma. We analyzed families with two or more cases of melanoma for germline mutations in CDKN2A and CDK4 to elucidate the contribution of these gene defects to familial malignant melanoma and to the occurrence of other cancer types.

METHODS

: The entire CDKN2A coding region and exon 2 of the CDK4 gene of an affected member of each of 52 families from southern Sweden with at least two cases of melanoma in first- or second-degree relatives were screened for mutations by use of polymerase chain reaction-single-strand conformation polymorphism analysis. Statistical tests were two-sided.

RESULTS

: CDKN2A mutations were found in 10 (19%) of the 52 families. Nine families carried an identical alteration consisting of the insertion of arginine at position 113 of p16(INK4a), and one carried a missense mutation, in which the valine at position 115 was replaced with a glycine. The 113insArg mutant p16(INK4a) was unable to bind cdk4 and cdk6 in an in vitro binding assay. Six of the 113insArg families had at least one member with multiple primary melanomas; the 113insArg families also had a high frequency of other malignancies-in particular, breast cancer (a total of eight cases compared with the expected 2.1; P =.0014) and pancreatic cancer (a total of six cases compared with the expected 0.16; P<.0001). Families with breast cancer also had a propensity for multiple melanomas in females, suggesting that a sex-dependent factor may modify the phenotypic expression of CDKN2A alterations.

CONCLUSIONS

: Our findings confirm that the majority of CDKN2A-associated melanoma families in Sweden are due to a single founder mutation. They also show that families with the CDKN2A 113insArg mutation have an increased risk not only of multiple melanomas and pancreatic carcinoma but also of breast cancer.

MEC1 and MEC2: two new cell lines derived from B-chronic lymphocytic leukaemia in prolymphocytoid transformation

We report the establishment and characterization of two cell lines, MEC1 and MEC2, that grew spontaneously on two subsequent occasions from the peripheral blood (PB) of a patient with B-chronic lymphocytic leukemia (B-CLL) in prolymphocytoid transformation. The patient was EBV-seropositive, his leukemic cells were EBNA negative, but the spontaneously grown cell lines are EBNA-2 positive. In liquid culture MEC1 cells grow adherent to the vessel wall and as tiny clumps; MEC2 cells do not adhere and form large clumps. The doubling time of MEC1 is 40h and of MEC2 is 31h. Both cell lines express the same light (kappa) and heavy chains (mu, delta) as the fresh parental B-CLL cells at the same high intensity, share the expression of mature B cell markers (CD19, CD20, CD21, CD22), differ in the expression of CD23 and FMC7, are CD11a+, CD18+, CD44+, CD49d+, CD54+ and express at high levels both CD80 and CD86. CD5 is negative on MEC1 cells (as on the vast majority of parental cells) and it has been lost by MEC2 cells after several months of culture. The cells have a complex karyotype. The tumour origin of MEC1 and MEC2 has been demonstrated by Southern blot analysis of the IgH loci and by Ig gene DNA sequencing. They use the VH4 Ig family and have not undergone somatic mutations (94.8% homology with germline Ig gene 4-59). Cytofluorographic analysis and RT-PCR reveal that MEC1 and MEC2 overexpress Bcl-2 together with Bax, express large amounts of Bcl-xL and trace amounts of Bcl-xS.

A primordial tRNA modification required for the evolution of life?

The evolution of reading frame maintenance must have been an early event, and presumably preceded the emergence of the three domains Archaea, Bacteria and Eukarya. Features evolved early in reading frame maintenance may still exist in present-day organisms. We show that one such feature may be the modified nucleoside 1-methylguanosine (m(1)G37), which prevents frameshifting and is present adjacent to and 3' of the anticodon (position 37) in the same subset of tRNAs from all organisms, including that with the smallest sequenced genome (Mycoplasma genitalium), and organelles. We have identified the genes encoding the enzyme tRNA(m(1)G37)methyltransferase from all three domains. We also show that they are orthologues, and suggest that they originated from a primordial gene. Lack of m(1)G37 severely impairs the growth of a bacterium and a eukaryote to a similar degree. Yeast tRNA(m(1)G37)methyltransferase also synthesizes 1-methylinosine and participates in the formation of the Y-base (yW). Our results suggest that m(1)G37 existed in tRNA before the divergence of the three domains, and that a tRNA(m(1)G37)methyltrans ferase is part of the minimal set of gene products required for life.

Phenotypic characterization of the human mast-cell line HMC-1

The cell line HMC-1, derived from a patient with mast cell leukaemia, is the only established cell line exhibiting a phenotype similar to that of human mast cells. This paper reports on a detailed characterization of the expression of a panel of markers for various types of immature and mature haematopoietic cells in the HMC-1. We also studied the potential of HMC-1 to differentiate upon treatment with conditioned media from the human T-cell line Mo, retinoic acid or DMSO. HMC-1 was found to express several mast cell-related markers. A high expression of Kit, the receptor for stem-cell factor, was detected. The majority of the cells were stained with a MoAb against the mast cell-specific serine protease tryptase. Of particular interest was the finding that beta-tryptase mRNA, but not alpha-tryptase mRNA, was expressed in HMC-1. Using enzyme-histochemistry we were able to show that the beta-tryptase was enzymatically active, indicating that tryptase can form active homotetramers. Both heparin and chondroitin sulfate were found to be present in approximately equal amounts. HMC-1 lacked surface expression of the high-affinity IgE receptor, which was confirmed by the absence of mRNA of the alpha- and beta-chains of the IgE-receptor complex. However, a strong expression of the gamma-chain of the IgE-receptor complex was detected. A positive staining of the monocyte/macrophage marker CD68 was obtained, as well as a strong hybridization signal for the eosinophilic/basophilic-related differentiation marker the Charcot-Leyden crystal. Treatment of HMC-1 with conditioned media from the human T-cell line Mo, retinoic acid or DMSO induced only moderate changes in the surface or intracellular expression of the studied markers. The agents tested neither induced any of the monocyte/granulocyte markers examined, nor expression of the Fc epsilon RI alpha-chain.

Phenotypic changes of human neuroblastoma cells in culture induced by 12-O-tetradecanoyl-phorbol-13-acetate

SK-N-SH and SH-SY5Y human neuroblastoma cells treated by 12-)-tetradecanoyl-phorbol-13-acetate(TPA) express morphological and biochemical changes, which indicate that differentiation towards more mature cells has occurred. The most prominent morphological changes were the development in 40-60% of the cells of cell-surface projections longer than 50 micrometers and cytoplasmic neurosecretory granules demonstrated by electron microscopy. At the biochemical level, TPA induced a two-fold increase in the relative activity of neuron-specific enolase and 30- to 40-fold increase in noradrenaline and adrenaline concentrations. A decrease in proliferation rate of TPA-treated cells was observed. The biological effects of TPA were slightly potentiated by nerve growth factor.

Phorbol ester-induced differentiation of chronic lymphocytic leukaemia cells

The croton oil-derived tumour-promoting agent 12-O-tetra-decanoyl-phorbol-13-acetate (TPA) exerts pleiotropic effects on the differentiation and proliferation of both normal and malignant animal and human cells in vitro. TPA is mitogenic in nanomolar concentration to chickens embryo fibroblasts and human T lymphocytes and inhibits the terminal differentiation of various committed embryonic cells and mouse Friend erythroleukaemia or myeloid leukaemia cells. TPA induces a terminal cell differentiation in some murine and human myeloid leukaemia and histiocytic lymphoma cells. We report here the effect of TPA on chronic lymphocytic leukaemia (CLL) biopsy cells in vitro. In four out of five CLL patients studied, TPA induced the appearance of 90-100% of lymphoblastoid and plasmacytoid cells after 4 days of culture. Under the influence of TPA, 86-97% of the cells expressed with time increasing amounts of intracytoplasmic immunoglobulin (C-Ig) of the same phenotype as that detected on the surface (S-Ig) of fresh, non-induced CLL cells. A parallel decrease in both monoclonal S-Ig density and DNA synthesis of the CLL cells was observed. Electron microscopic studies showed a muturation towards plasma cells. We therefore conclude that TPA is capable of inducing differentiation of CLL cells in vitro.

Association of Rickettsia helvetica with chronic perimyocarditis in sudden cardiac death

BACKGROUND

Rickettsia helvetica is the only non-imported rickettsia found in Scandinavia. It was first detected in Ixodes ricinus ticks, but has never been linked to human disease. We studied two young Swedish men who died of sudden cardiac failure during exercise, and who showed signs of perimyocarditis similar to those described in rickettsial disease.

METHODS

Samples from the heart and other organs were analysed by PCR and DNA sequencing. May-Grünwald-Giemsa, Grocott, and acridine-orange stains were used for histopathological examinations. Staining of R. helvetica grown on shell-vials in vero cells, and the early descriptions of R. rickettsii by H T Ricketts and S B Wohlbach served as controls. Immunohistochemistry was done with Proteus OX-19 rabbit antisera as the primary antibody. The structure of rickettsia-like organisms was investigated by transmission electron microscopy. Serological analyses were carried out by indirect immunofluorescence with R. helvetica as the antigen.

FINDINGS

By use of a semi-nested PCR, with primers specific for the 16S rRNA and 17-kDa outer-membrane-protein genes, and sequence analysis of the amplified products, genetic material from R. helvetica was detected in the pericardium and in a lymph node from the pulmonary hilum in case 1, and in a coronary artery and the heart muscle in case 2. A serological response in case 1 revealed an endpoint titre for R. helvetica of 1/320 (1/256 with R. rickettsii as the antigen). Examination of PCR-positive tissue showed chronic interstitial inflammation and the presence of rickettsia-like organisms predominantly located in the endothelium. These organisms reacted with Proteus OX-19 antisera, and their size and form were consistent with rickettsia. Electron microscopy confirmed that the appearance of the organisms was similar to that described for spotted-fever rickettsia.

INTERPRETATION

R. helvetica, transmitted by I. ricinus ticks, may be an important pathogen in the aetiology of perimyocarditis, which can result in sudden unexpected cardiac death in young people.

Tumorigenicity of human hematopoietic cell lines in athymic nude mice

Human hematopoietic cell lines, which had been classified on the basis of studies on clonality, and morphological, chromosomal and functional parameters as lymphoblastoid cell lines (LCL) of presumed non-neoplastic origin, and lymphoma, myeloma and leukemia lines of proven malignant origin, were tested for tumorigenic potential on subcutaneous transplantation to nude mice and for capacity to grow in semi-solid medium in vitro. Recently established LCL failed to grow both in nude mice and in agarose. In contrast, some of the LCL which had developed secondary chromosomal alterations during continuous cultivation for periods exceeding several years were tumorigenic and/or had the capacity to form colonies in agarose. Most lymphoma lines formed colonies in agarose and tumors in the mice. One of the two myeloma lines formed subcutaneous tumor which, however, showed no progressive growth. The other myeloma line failed to grow. Both myeloma lines, however, formed colonies in agarose. The myeloid leukemia line was tumorigenic while two of the three tested lymphocytic leukemia lines failed to grow in the mice. All leukemia lines formed colonies in agarose. We conclude from this study that: (1) Of the two types of Epstein-Barr virus containing cell lines [LCL and Burkitt lymphoma (BL) lines], only BL lines were shown to form tumors when inoculated subcutaneously in nude mice and had the capacity to grow in agarose in vitro. This shows that EBV transformation per se does not necessarily render lymphocytes tumorigenic in nude mice. The capacity to form colonies in agarose is not acquired either. (2) Changes of the karyotype and several phenotypic characteristics which occur in the originally diploid LCL during prolonged cultivation in vitro may be accompanied by the acquisition of the potential to grow subcutaneously in nude mice and in agarose in vitro. (3) The inconsistency with regard to the capacity of come of the neoplastic cell lines to grow in nude mice or in agarose seems to underline that neither of the two tests is a reliable criterion for malignancy of human lymphoma, leukemia and myeloma cell lines.

Traffic flow in the operating room: an explorative and descriptive study on air quality during orthopedic trauma implant surgery

BACKGROUND

Understanding the protective potential of operating room (OR) ventilation under different conditions is crucial to optimizing the surgical environment. This study investigated the air quality, expressed as colony-forming units (CFU)/m(3), during orthopedic trauma surgery in a displacement-ventilated OR; explored how traffic flow and the number of persons present in the OR affects the air contamination rate in the vicinity of surgical wounds; and identified reasons for door openings in the OR.

METHODS

Data collection, consisting of active air sampling and observations, was performed during 30 orthopedic procedures.

RESULTS

In 52 of the 91 air samples collected (57%), the CFU/m(3) values exceeded the recommended level of <10 CFU/m(3). In addition, the data showed a strongly positive correlation between the total CFU/m(3) per operation and total traffic flow per operation (r = 0.74; P = .001; n = 24), after controlling for duration of surgery. A weaker, yet still positive correlation between CFU/m(3) and the number of persons present in the OR (r = 0.22; P = .04; n = 82) was also found. Traffic flow, number of persons present, and duration of surgery explained 68% of the variance in total CFU/m(3) (P = .001).

CONCLUSIONS

Traffic flow has a strong negative impact on the OR environment. The results of this study support interventions aimed at preventing surgical site infections by reducing traffic flow in the OR.

Human mast cells express functional TrkA and are a source of nerve growth factor

Mast cells are the principal effector cells in IgE-dependent hypersensitivity reactions. Despite reports that rodent mast cells proliferate in the presence of nerve growth factor (NGF), human mast cells reportedly do not respond to this factor. To determine if human mast cells express the NGF receptors, TrkA tyrosine receptor and the low affinity NGF receptor (LNGFR), we first analyzed the mRNA expression by RT-PCR of TrkA and LNGFR in a human mast cell line (HMC-1) and in human mast cells cultured in the presence of stem cell factor. Both HMC-1 and cultured human mast cells were found to express TrkA but not LNGFR. TrkA protein was demonstrated by Western blot analysis of HMC-1 lysates. Using flow cytometric analysis and mast cell tryptase as a mast cell marker, both HMC-1 cells and cultured human mast cells were shown to coexpress tryptase and TrkA. Treatment of mast cells with NGF resulted in phosphorylation of TrkA on tyrosine residues as detected by immunoblotting with an antiphosphotyrosine antibody. Furthermore, NGF induced the immediate early gene c-fos in HMC-1 cells. HMC-1 cells and cultured human mast cells were also found to express NGF mRNA, and conditioned medium from HMC-1 cells stimulated neurite outgrowth from chicken embryonic sensory ganglia in culture. This effect was blocked by anti-NGF. Thus, mast cells express functional TrkA and synthesize NGF, suggesting a mechanism by which NGF may act as an autocrine factor for human mast cells, and by which mast cells and nerves may interact.