Pulse-shape discrimination against low-energy Ar-39 beta decays in liquid argon with 4.5 tonne-years of DEAP-3600 data

The DEAP-3600 detector searches for the scintillation signal from dark matter particles scattering on a 3.3 tonne liquid argon target. The largest background comes from 39 Ar beta decays and is suppressed using pulse-shape discrimination (PSD). We use two types of PSD estimator: the prompt-fraction, which considers the fraction of the scintillation signal in a narrow and a wide time window around the event peak, and the log-likelihood-ratio, which compares the observed photon arrival times to a signal and a background model. We furthermore use two algorithms to determine the number of photons detected at a given time: (1) simply dividing the charge of each PMT pulse by the mean single-photoelectron charge, and (2) a likelihood analysis that considers the probability to detect a certain number of photons at a given time, based on a model for the scintillation pulse shape and for afterpulsing in the light detectors. The prompt-fraction performs approximately as well as the log-likelihood-ratio PSD algorithm if the photon detection times are not biased by detector effects. We explain this result using a model for the information carried by scintillation photons as a function of the time when they are detected.

First Results from the DEAP-3600 Dark Matter Search with Argon at SNOLAB

This Letter reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 ton day) of data taken during the initial filling phase demonstrates the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage <1.2×10^{-7} (90% C.L.) between 15 and 31  keV_{ee}. No candidate signal events are observed, which results in the leading limit on weakly interacting massive particle (WIMP)-nucleon spin-independent cross section on argon, <1.2×10^{-44}  cm^{2} for a 100  GeV/c^{2} WIMP mass (90% C.L.).

Activation of the p53 pathway by the MDM2 inhibitor nutlin-3a overcomes BCL2 overexpression in a preclinical model of diffuse large B-cell lymphoma associated with t(14;18)(q32;q21)

p53 is frequently wild type (wt) in diffuse large B-cell lymphoma (DLBCL) associated with t(14;18)(q32;q21) that overexpresses BCL2. Nutlin-3a is a small molecule that activates the p53 pathway by disrupting p53–MDM2 interaction. We show that nutlin-3a activates p53 in DLBCL cells associated with t(14;18)(q32;q21), BCL2 overexpression and wt p53, resulting in cell cycle arrest and apoptosis. Nutlin-3a treatment had similar effects on DLBCL cells of activated B-cell phenotype with wt p53. Cell cycle arrest was associated with upregulation of p21. Nutlin-3a-induced apoptosis was accompanied by BAX and PUMA upregulation, BCL-XL downregulation, serine-70 dephosphorylation of BCL2, direct binding of BCL2 by p53, caspase-9 upregulation and caspase-3 cleavage. Cell death was reduced when p53-dependent transactivation activity was inhibited by pifithrin-α (PFT-α), or PFT-μ inhibited direct p53 targeting of mitochondria. Nutlin-3a sensitized activation of the intrinsic apoptotic pathway by BCL2 inhibitors in t(14;18)-positive DLBCL cells with wt p53, and enhanced doxorubicin cytotoxicity against t(14;18)-positive DLBCL cells with wt or mutant p53, the latter in part via p73 upregulation. Nutlin-3a treatment in a xenograft animal lymphoma model inhibited growth of t(14;18)-positive DLBCL tumors, associated with increased apoptosis and decreased proliferation. These data suggest that disruption of the p53–MDM2 interaction by nutlin-3a offers a novel therapeutic approach for DLBCL associated with t(14;18)(q32;q21).

Independent measurement of the total active 8B solar neutrino flux using an array of 3He proportional counters at the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) 8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.

Effects of buthionine sulfoximine treatment on diaphragm contractility and SR Ca2+ pump function in rats

The purpose of this study was to examine the effects of glutathione (GSH) depletion and cellular oxidation on rat diaphragm contractility and sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) function in vitro under basal conditions and following fatiguing stimulation. Buthionine sulfoximine (BSO) treatment (n = 10) for 10 days (20 mM in drinking water) reduced (P < 0.05) diaphragm GSH content (nmol/mg protein) and the ratio of GSH to glutathione disulfide (GSH/GSSG) by 91% and 71%, respectively, compared with controls (CTL) (n = 10). Western blotting showed that Hsp70 expression in diaphragm was not increased (P > 0.05) with BSO treatment. As hypothesized, basal peak twitch force (g/mm(2)) was increased (P < 0.05), and fatigability in response to repetitive stimulation (350-ms trains at 100 Hz once every 1 s for 5 min) was also increased (P < 0.05) in BSO compared with CTL. Both Ca(2+) uptake and maximal SERCA activity (mumol.g protein(-1).min(-1)) measured in diaphragm homogenates that were prepared at rest were increased (P < 0.05) with BSO treatment, an effect that could be partly explained by a twofold increase (P < 0.05) in SERCA2a expression with BSO. In response to the 5-min stimulation protocol, both Ca(2+) uptake and maximal SERCA activity were increased (P < 0.05) in CTL but not (P > 0.05) in BSO diaphragm. We conclude that 1) cellular redox state is more optimal for contractile function and fatigability is increased in rat diaphragm following BSO treatment, 2) SERCA2a expression is modulated by redox signaling, and 3) regulation of SERCA function in working diaphragm is altered following BSO treatment.

Establishment and characterization of a new mantle cell lymphoma cell line, Mino

Mantle cell lymphoma (MCL) is a distinct type of B-cell non-Hodgkin's lymphoma characterized by cyclin D1 overexpression and the cytogenetic abnormality, the t(11;14)(q13;q32). MCL cell lines have been difficult to establish and in vitro studies of these neoplasms are scarce. We describe the establishment and characteristics of a new MCL cell line, Mino. The cells are large, growing singly and in small clumps in vitro. By flow cytometry, the immunophenotype was compatible with MCL (i.e. CD5+CD20+CD23-FMC7+). Conventional cytogenetics showed hyperdiploidy with multiple complex karyotypic abnormalities, but no evidence of the t(11;14), proven to be present only by fluorescence in situ hybridization and polymerase chain reaction (PCR) methods. Western blots showed expression of cyclin D1 but no detectable cyclin D2 and cyclin D3; the retinoblastoma protein was predominantly phosphorylated. There was expression of tumor suppressor gene products including p53, p16(INK4a), and p21(WAF1). Sequencing of the TP53 gene revealed a mutation (codon 147(valine-->glycine)) in exon 5. Epstein Barr virus was absent. In summary, Mino is a new MCL cell line that may be useful to study the pathogenesis of MCL.

Measurement of day and night neutrino energy spectra at SNO and constraints on neutrino mixing parameters

The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.

Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory

Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.

Measurement of the rate of nu(e) + d --> p + p + e(-) interactions produced by (8)B solar neutrinos at the Sudbury Neutrino Observatory

Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).

Differential expression of BCL-2 family proteins in ALK-positive and ALK-negative anaplastic large cell lymphoma of T/null-cell lineage

Anaplastic large-cell lymphoma (ALCL) of T- or null-cell lineage, as defined in the revised European-American lymphoma classification, includes a subset of tumors that carry the t(2;5)(p23;q35) resulting in overexpression of anaplastic lymphoma kinase (ALK). Patients with ALK+ ALCL are reported to have a better prognosis than patients with ALK- ALCL. Because the mechanisms for this survival difference are unknown, we investigated the hypothesis that apoptotic pathways may be involved. We therefore assessed expression levels of the anti-apoptotic proteins BCL-2 and BCL-XL and the pro-apoptotic proteins BAX and BCL-XS in T/null-cell ALCL using immunohistochemical methods and correlated the findings with ALK expression and apoptotic rate (AR), the latter assessed by a modified Tdt-mediated dUTP nick-end labeling assay. ALK was detected in 21 of 66 (31.8%) ALCLs. BCL-2 was not detected in 21 ALK+ ALCLs but was present in 26 of 45 (57.8%) ALK- ALCLs (P < 0.0001). ALK+ and ALK- ALCLs also showed significant differences in expression of BCL-XL, BAX, and BCL-XS. ALK+ tumors less commonly had a high level of BCL-XL (1 of 17 versus 14 of 35, P = 0.01), and more commonly had high levels of BAX (13 of 18 versus 15 of 36, P = 0.05), and BCL-XS (11 of 16 versus 12 of 31, P = 0.05) compared with ALK- tumors. ALK+ tumors also had a higher mean AR than ALK- tumors (3.4% versus 1.1%, P = 0.0002). Differential expression of BCL-2 family proteins may be responsible for the higher AR observed in ALK+ ALCL and provides a possible biological explanation for the better prognosis reported for patients with ALK+ ALCL.

B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma involving bone marrow with an interfollicular pattern

B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) may involve the bone marrow in nodular, interstitial, diffuse, or mixed patterns. However, B-cell CLL/SLL associated with large reactive germinal centers (the so-called interfollicular pattern) involving the bone marrow is not reported. We describe 2 examples of B-cell CLL/SLL that subtotally replaced the bone marrow with an interfollicular pattern. In both cases, the neoplasms were composed of small round lymphoid cells; proliferation centers also were present. The neoplasms surrounded large reactive germinal centers that were devoid of peripheral mantle zones. The germinal centers were paratrabecular and nonparatrabecular in case 1 and nonparatrabecular in case 2. Flow cytometry immunophenotypic studies done on bone marrow aspiration samples of both cases showed a uniform population of neoplastic cells positive for pan-B-cell antigens and the CD5 and CD23 antigens. Immunohistochemical studies done on bone marrow biopsy sections supported the flow cytometry results and demonstrated that the germinal centers were negative for BCL-2. B-cell CLL/SLL may rarely involve the bone marrow with an interfollicular pattern. Knowledge of this pattern will prevent confusion with follicle center lymphoma and large cell transformation, both of which initially were considered in the differential diagnosis of these cases.

Development of intermediate-grade (mantle cell) and low-grade (small lymphocytic and marginal zone) human non-Hodgkin's lymphomas xenotransplanted in severe combined immunodeficiency mouse models

We have used severe combined immunodeficiency (SCID) (c.b.-17, ICR/SCID) mice to develop xenotransplantation (XT) models for human intermediate-and-low-grade non-Hodgkin's lymphomas (NHL). In the past, SCID mice have provided a variety of useful XT models for human hematopoietic neoplasms that primarily involve the acute leukemias and some nonhematopoietic tumors, but only rare reports exist on use of the SCID mouse model in the study of primary tumor cells from NHL. Intermediate-grade and low-grade NHL are the most common lymphomas seen in adults. There is no effective therapy for those types of NHL, and they have not been established in an animal model to date. The lack of an animal model has hampered studies that can evaluate the disease process in vivo as well as the definition of therapeutic parameters involved in treatment. We report in this study that primary patient samples of NHL ( intermediate grade and low grade) have been successfully established in SCID mice after XT. NHL include intermediate-grade (mantle cell lymphoma) and low-grade (eg, small lymphocytic lymphoma/chronic lymphocytic lymphoma and marginal zone lymphoma) forms. Studies have been directed toward creating appropriate conditions for the optimal grafting of these NHL in SCID mice so that the disease process in humans could be accurately simulated. These studies indicate that development of XT-human lymphoma cells in SCID mice appear to be linked to their biologic and/or clinical behavior, transplanted lymphoma cell number, and age, as well as to the natural killer cell status of the SCID mouse recipients. Evidence has also shown that NHL cells can exhibit homing or trafficking patterns in SCID recipients that resemble those observed in patients with gastrointestinal lymphomatous involvement (particularly that of mantle cell lymphoma). Our studies also indicate that artefactual influences, such as the outgrowth of Epstein-Barr virus-associated lymphoblastoid lesions, are rare occurrences in the human NHL/SCID models that we have established.

Increased tumor cell proliferation in murine tumors with decreasing dosage of wild-type p53

A number of transgenic animal model systems have addressed the mechanistic role of p53 loss in tumor progression. However, many of these tumor models have analyzed p53 function in the context of other transgenes expressing activated oncogenes or defective tumor suppressor genes generated by gene targeting. To examine the role of p53 loss independent of other exogenous oncogenic influences, we analyzed some of the biological aspects of tumor formation and progression in p53-knockout mice containing a null germline p53 allele. We analyzed tumors from p53-/-, p53+/-, and p53+/+ littermates. Some of the p53+/- tumors had lost the remaining p53 allele (p53+/- loss of heterozygosity), whereas others retained the allele (p53+/-). In this report, we show that loss or absence of p53 conferred a tumor growth advantage by increasing the rate of cellular proliferation in a p53 dosage-dependent manner. The apoptotic levels in tumor tissue were found to be modest and not significantly dependent on p53 status. These results contrast with those from some other p53-deficient tumor models, in which p53 loss was associated with more rapid tumor progression through abrogated apoptosis. Finally, as p53 has been shown to regulate certain angiogenic factors, we examined the levels of angiogenesis in p53-containing and p53-deficient tumors. We found no p53-dependent differences in the levels of tumor angiogenesis measured by intratumoral microvessel density.

Retinoid-mediated inhibition of cell growth with stimulation of apoptosis in aggressive B-cell lymphomas

Retinoids have been shown to modulate cell growth and differentiation in a variety of human tumor cell types, but their effects on B-cell non-Hodgkin's lymphomas (NHL-B) have not been explored. In this study, all-trans retinoic acid (ATRA) in the free form and liposome-encapsulated form (L-ATRA) were used to determine effects on fresh NHL-B patient cells as well as cell lines recently established from both HIV-negative and -positive NHL-B patient biopsies. Both ATRA and L-ATRA were found to inhibit cell proliferation in NHL-B cells. However, L-ATRA was found to be superior to free ATRA in inhibiting cell proliferation of NHL-B cells and resulted in greater than 90% cell growth inhibition in a dose-dependent manner. In addition, L-ATRA also induced high levels of apoptosis in NHL-B cells in vitro. To delineate the apoptotic pathways involved, the expression of the apoptosis suppressor oncogene bcl-2 was evaluated in different NHL-B cells with and without the t(14;18) chromosomal translocation. After L-ATRA exposure, more than a 50% reduction in the expression of bcl-2 protein was observed. bcl-2 message levels were also down-regulated in the L-ATRA-sensitive NHL-B cells. Bax protein levels were analyzed and found to be up-regulated in L-ATRA-sensitive NHL-B cells. Similar results were observed in sensitive AIDS/lymphoma cell lines. Experiments using an RAR-alpha antagonist (RO 41-5253) showed that both the proliferation inhibition and apoptosis induced by L-ATRA could be blocked in NHL-B cells. The findings of the present study indicate that L-ATRA may possess therapeutic potential in blocking cell proliferation, inducing apoptosis, and

Effects of genetic background on tumorigenesis in p53-deficient mice

Mice with disrupted germline p53 alleles have been engineered by us and others and have been shown to have enhanced susceptibility to spontaneous tumors of various types. We monitored a large number of p53-deficient mice (p53+/- and p53-/-) and their wild-type littermates (p53+/+) of two different genetic backgrounds (129/Sv and mixed C57BL/6 x 129/Sv) up to 2 yr of age. p53+/- and p53-/- 129/Sv mice show accelerated tumorigenesis rates compared with their p53-deficient counterparts of mixed C57BL/6 x 129/Sv genetic background. The tumor spectra of the two strains of mice are similar except that almost half of 129/Sv p53-/- males develop malignant teratomas, whereas these tumors are rarely observed in C57BL/6 x 129/Sv mice and never in 129/Sv p53+/- males. In the study reported here, we further characterized the lymphomas that arose in the p53-nullizygous mice and found that over three-quarters of the lymphomas were of thymic origin and contained primarily immature (CD4+/CD8+) T-cells, whereas the remainder originated in the spleen and peripheral lymph nodes and were of B-cell type. The high incidence of early-onset lymphomas in the nullizygous mice makes these animals a good lymphoma model, whereas the heterozygous mice may be a useful model for Li-Fraumeni syndrome, a human inherited cancer predisposition.

Fas/APO-1 expression and function on malignant cells of hematologic and nonhematologic origin

Fas/APO-1 is a cell-surface protein capable of inducing apoptosis in a variety of cell types upon specific antibody engagement. Antibodies against Fas/APO-1 have been used successfully for the treatment of several lymphoid malignancies in mice. Before apoptosis triggered by anti-Fas can be fully exploited as a clinical therapy, Fas/APO-1 distribution, function, and regulation must be further studied. In this study, we analyzed freshly isolated B-cell and T-cell lymphomas as well as nonhematological tumor cell lines for Fas/APO-1 expression and sensitivity to the growth-inhibitory effects of anti-Fas. Constitutive Fas/APO-1 was expressed at very low levels on only one of eight B-cell lymphomas analyzed. Expression was markedly up-regulated, however, by culture with high-molecular-weight B-cell growth factor (HMW-BCGF). Fas/APO-1 was constitutively expressed on one of two T-cell lymphomas examined at levels comparable to those of activated normal lymphocytes. However, neither the B-cell nor T-cell lymphomas positive for Fas/APO-1 expression were growth inhibited by anti-Fas. Furthermore, in the case of one HMW-BCGF-activated B-cell lymphoma, a significant growth enhancement was observed upon anti-Fas treatment. Nonhematologic tumor cell lines showed a similar spectrum of biologic responses to anti-Fas, being growth inhibited, growth stimulated or unaffected by antibody treatment. In summary, these studies suggest that engagement of Fas/APO-1 may trigger a diverse spectrum of biologic effects not unlike other members of the nerve growth factor receptor/tumor necrosis factor receptor superfamily.

Proliferating cell nuclear antigen (PCNA) expression in chronic lymphocytic leukemia (CLL)

Chronic Lymphocytic Leukemia (CLL) is usually an indolent disorder which in some patients assumes an aggressive clinical course. In order to assess at presentation the prognosis of a given patient, several staging systems and prognostic variables have been proposed including the expression of the Proliferating Cell Nuclear Antigen (PCNA). PCNA is a 36 kd nuclear protein, the regulation of which is cell cycle-dependent. In CLL, PCNA levels correlate with cell proliferation, clinical stage and the lymphocyte doubling time (LDT). Furthermore, preliminary data suggests that PCNA expression may also predict response to Fludarabine-based chemotherapy. Since PCNA is a cofactor for Delta DNA polymerase, PCNA overexpression in CLL may also reflect the intrinsic DNA repair activity of the leukemic cells and thus their resistance to chemotherapy. Further studies aiming at modulation of PCNA expression in CLL cells may clarify this issue and may offer a future new therapeutic strategy with which to treat this disorder.

Identification of a cDNA for a human high-molecular-weight B-cell growth factor

Proliferation is necessary for many of the phenotypic changes that occur during B-cell maturation. Further differentiation of mature B cells into plasma cells or memory B cells requires additional rounds of proliferation. In this manuscript, we describe a cDNA for a human B-cell growth factor we call high-molecular-weight B-cell growth factor (HMW-BCGF). Purified HMW-BCGF has been shown to induce B-cell proliferation, inhibit immunoglobulin secretion, and selectively expand certain B-cell subpopulations. Studies using antibodies to HMW-BCGF and its receptor have suggested that HMW-BCGF, while produced by T cells and some malignant B cells, acts predominantly on normal and malignant B cells. The HMW-BCGF cDNA was identified by expression cloning using a monoclonal antibody and polyclonal antisera to HMW-BCGF. Protein produced from the cDNA induced B-cell proliferation, inhibited immunoglobulin secretion, and was recognized in immunoblots by anti-HMW-BCGF antibodies. The amino acid sequence of HMW-BCGF deduced from the cDNA predicts a secreted protein of 53 kDa with three potential N-linked glycosylation sites. The identification of this cDNA will allow further studies examining physiologic roles of this cytokine. We propose to call it interleukin 14.

Human B cell lymphomas: in vitro and in vivo studies on growth factors and cell growth

The B cell non-Hodgkin's lymphomas (NHL-B) are a common, but heterogeneous group of human lymphoid neoplasms, consisting of monoclonal populations of neoplastic B lymphocytes demonstrating non-random chromosomal abnormalities, often associated with proto-oncogene translocations. Clinically and pathologically, these lymphomas are classified as low, intermediate, or high grade, according to the clinical aggressiveness of the NHL-B subtype. The clinical behavior can also be correlated with biological function regarding proliferative capabilities of the tumor cells. Our studies have shown that the low grade B cell lymphomas have low constitutive proliferative capacity in vitro and do not respond to cytokine growth factors (CGF), while the high grade NHL-B respond to the B cell growth factor (BCGF) family of CGFs. The high grade NHL-B also secrete BCGFs both in vitro and in vivo, as autocrine growth factors that may provide a target for new therapeutic approaches to therapy.

Studies on a type D retrovirus isolated from an AIDS patient lymphoma

The development of AIDS-related lymphomas (ARL) has been on the rise in recent years. During an analysis of ARL from AIDS patients, one individual developed atypical syncytial variants of high-grade Burkitt's-type B-cell lymphomas, which prompted further study. However, the search for a HIV-1 retrovirus, which we hypothesized was infecting these cells, led to the subsequent discovery of a type D retrovirus in two early-passage lymphoma cell lines derived from this patient. Nucleotide and amino acid sequence analysis, as well as immunologic reactivity, indicated that the virus was closely related to Mason-Pfizer monkey virus (MPMV) or simian retrovirus type 1 (SRV-1). MPMV and SRV-1 are immunosuppressive type D retroviruses that cause an AIDS-like syndrome in rhesus macaques. Amplification of DNA from the patient's diagnostic bone marrow biopsy specimen by the polymerase chain reaction generated MPMV-specific fragments indicative of infection by a retrovirus similar to MPMV. Additionally, the patient's serum contained antibodies that recognized type D retroviral env proteins (gp20 and gp70) and gag proteins (p27 and p14) as assayed by immunoblot and radioimmunoprecipitation techniques. Although there have been reports of human cell lines infected with type D retroviruses and of type D reactive human sera, this is the first report of a type D retrovirus infection in a human confirmed by virus isolation, serum immunoreactivity, and viral DNA identification in tumor tissue.

Chromosome 17- and p53 changes in lymphoma

The clinical course of lymphoma patients in whom rearrangements or deletions of the short arm of chromosome 17 (17p) were evident by cytogenetics was rapidly progressive with a short survival. The gene for the protein designated p53 resides in 17p. We studied four lymphoma cell lines derived from human tumours, and 25 tumour samples of patients with lymphomas, for any evidence of p53 genomic changes by Southern blot technique. The four cell lines and four of the 25 tumour samples showed numerical changes of chromosome 17 or structural abnormalities of 17p (translocations or deletions). Allelic loss of the p53 gene was found in two of the four cell lines, and one of these in addition showed a rearrangement of the 3' end of the gene. Of the four tumours known to have chromosome 17 abnormality, one specimen showed allelic loss of the p53 gene. None of the remaining tumour samples showed any significant change. These studies suggest that acquisition of changes in the short arm of chromosome 17, which may be interrelated with the p53 gene, may carry a poor prognosis in patients with non-Hodgkin's lymphoma.

Isolation of a type D retrovirus from B-cell lymphomas of a patient with AIDS

An atypical syncytial variant of a high-grade Burkitt's-type B-cell lymphoma from a patient with AIDS who was seropositive for human immunodeficiency virus type 1 was studied. A productive type D retrovirus infection was identified in early-passage cell lines derived from two lymphomas from this patient. Nucleotide and amino acid sequence analysis as well as immunologic reactivity indicated that the isolated virus was highly related to Mason-Pfizer monkey virus (MPMV). MPMV is an immunosuppressive type D retrovirus that causes an AIDS-like syndrome in rhesus macaques. Amplification of DNA from the patient's diagnostic bone marrow biopsy specimen by polymerase chain reaction generated the appropriate MPMV-specific fragments and indicated that the patient was infected with the MPMV-like retrovirus. In addition, the patient's serum contained antibodies which recognized type D viral env proteins (gp70 and gp20) and gag proteins (p27 and p14). Although there have been reports of human cell lines infected with type D retroviruses and of type D-reactive human sera, this is the first evidence of a type D retrovirus infection in a human confirmed by virus isolation, serum reactivity, and viral DNA identification in tumor tissue.

The use of primers from highly conserved pol regions to identify uncharacterized retroviruses by the polymerase chain reaction

Two degenerate oligonucleotide primers derived from regions of pol conserved among retroviruses have been synthesized. Polymerase chain reactions utilizing these primers amplify a 135-bp pol fragment in every retrovirus DNA tested to date. The polymerase chain reaction has been linked to a reverse transcriptase step so that a pol-specific DNA fragment can be obtained from a moderate amount of a purified retrovirus or viral RNA. The identity of an unknown retrovirus can be determined by sequencing of the amplified fragment following molecular cloning. This procedure was tested on an unidentified (non-HIV) retrovirus expressed by a B-cell lymphoma line obtained from an AIDS patient. Our PCR assay identified the retrovirus as being highly similar to Mason-Pfizer monkey virus (MPMV) and simian retrovirus 1, which are closely related immunosuppressive type D viruses that cause simian AIDS.

Establishment and characterization of human B-cell lymphoma cell lines using B-cell growth factor

B-cell non-Hodgkin's lymphomas (NHL-B) have been difficult to establish in long-term cell culture using standard techniques. We report the establishment of five representative cell lines from high grade NHL-B using B-cell growth factor (BCGF). The five NHL-B cell lines display the morphologic, immunophenotypic, genotypic, and biologic characteristics of the lymphoma cells present in the original diagnostic specimen. The cell lines showed at least a sevenfold dose-dependent increase in proliferation in vitro over background in the presence of BCGF. Other putative B-cell growth-stimulating cytokines showed no significant proliferative activity or were inhibitory in some cases. NHL-B cell lines secreted growth factor(s) into culture supernatants that mediated at least a fivefold dose-dependent increase in cell proliferation in autochthonous lymphoma cells and a 10-fold or greater stimulation in growth factor-dependent normal B cell lines in vitro. The cell lines show monoclonal rearrangements of IgH genes and nonrandom chromosomal abnormalities characteristic of NHL-B, while the expression of Epstein-Barr virus associated antigen (EBNA-I) is present in two of the five cell lines. The studies show that lineage-specific growth factors may be used to establish neoplastic B cell lines in vitro, which are important experimental systems for cellular and molecular studies in the NHL-B.

Isolation and characterization of growth factor(s) from a human B-cell lymphoma

We demonstrate that human neoplastic B cells (Br cells) contain a cytoplasmic protein of molecular mass 60 Kd that exhibits B-cell growth factor (BCGF) activity on growth factor-dependent long-term human B cells as well as on autochthonous tumor cells. This 60-Kd protein is recognized by antibodies against a similar intracellular 60-Kd protein derived from normal human lymphocytes. These results demonstrate that the two proteins share epitope homology. Microculture bioassays indicate that neoplastic and normal 60-Kd proteins are capable of driving neoplastic B cells through S-phase. Western immunoblot analysis indicates that neoplastic B cells secrete 60- as well as 14-Kd protein. Immunoaffinity-purified proteins secreted by Br cells exhibit BCGF activity in anti-IgM or dextran sulfate-preactivated human B cells. In addition, a double-antibody immunofluorescence staining technique was used to demonstrate that Br cells express cell surface receptors for BCGF molecule(s). These studies provide support for the autocrine growth model for neoplastic human B cells and suggest that the autocrine growth factor derived from such tumor cells is similar if not identical to normal BCGF molecules.

In vitro analysis of cell populations involved in Hodgkin's disease lesions and in the characteristic T cell immunodeficiency

Hodgkin's disease (HD) is an aggressive human lymphoproliferative disease that displays a curious pleomorphic histopathologic appearance unlike that of any of the common non-Hodgkin's lymphomas (NHL). Although the bizarre giant cells of the HD lesion, the Reed-Sternberg cells (RSC) and mononuclear variant Hodgkin's cells (HC), have been considered to be malignant cells, little objective evidence supports this conclusion. We have studied the proliferative characteristics of T cell as well as RSC and HC-enriched populations from HD lesions, and found the majority of the proliferative activity in the T cell populations. RSC-enriched populations not only showed little spontaneous proliferation, but also did not respond to a variety of cytokine growth factors in vitro, suggesting that these cell populations are not actively growing cells. Further molecular studies to identify possible monoclonal T or B cell populations in HD lesions, using a TCR beta chain probe and IgH probes respectively on Southern blot analysis, revealed no evidence of monoclonal lymphoid cell populations. Additional studies on the characteristic T cell immunodeficiency in HD were also undertaken. Our previous studies had associated a decrement in IL-2 production with this defect. Our studies now show that an intrinsic T cell abnormality exists when HD patients' T cells are stimulated with agonistic MAb that can optimally activate and stimulate IL-2 production in normal control T cells.

In vitro studies on leukemia cells and T lymphocytes in hairy cell leukemia

Hairy cell leukemia cell lines were established from eight untreated patients using purified B cell growth factor (BCGF) in vitro. These cell lines maintained their original cell surface immunophenotype for about 1 month, after which they began to lose one or more of their characteristic surface antigens. The cell lines also maintained typical hairy cell leukemia morphology for 2-3 months in vitro but later showed an increasing number of multinucleate giant cells that maintained a B cell surface phenotype. The cell lines became independent of exogenously provided BCGF after at least 1 month in vitro and secreted BCGF activity into culture supernatants in most cases. Some cell lines also acquired Epstein-Barr virus nuclear antigen positivity after variable period. Two hairy cell leukemia patients also showed hyperactive T cell responses in vitro and exhibited spontaneous T cell proliferation in culture without exogenously supplied interleukin-2. These T cell lines had the T helper phenotype and secreted significant amounts of T cell-associated lymphokines with BCGF and interleukin-2 activity into culture supernatants.

Double immunoenzymatic labeling of lymphomatous tissues for both immunologic phenotype and a malignancy-associated nucleolar antigen

Defining cell lineage in the non-Hodgkin's lymphomas (NHL) is challenging for the immunopathologist. Cell surface marker techniques have made a major contribution to the understanding of the biology and classification of lymphoproliferative disorders by permitting the determination of the lymphoid (B- or T-cell) or monocytic lineage of the tumors. Because lymphoma cells often simulate the morphologic features and cell surface phenotype of their normal lymphocytic counterparts, it is difficult to discriminate normal from neoplastic lymphocytes. The authors have used representative monoclonal antibodies (MAb) to cell surface antigens to assess tumor cell surface antigens associated with various lymphoreticular cell lineages. Heteroantisera to the human malignancy-associated nucleolar antigen (HMNA) was utilized as a marker for neoplastic lymphoid cells as previously described. The use of double immunoenzymatic staining with both peroxidase and alkaline phosphatase allow us simultaneously to determine lymphoid lineage and malignancy on human lymphoma cells. In 101 cases of various cell types of NHL, the anti-HMNA antiserum reacted with nucleoli in the morphologically neoplastic lymphoma cells, but not with normal-appearing lymphoid and other cell types present in the lesions. Control specimens from normal and hyperplastic lymphoid tissue also failed to react with anti-HMNA antibodies.

Production of B cell growth factor(s) by neoplastic B cells from hairy cell leukemia patients

Recent studies have shown that normal human T cells contain a high-molecular-weight (mol wt) protein exhibiting B cell growth factor (BCGF) activity. Other studies have shown that virally transformed human B cells also secrete a high-mol-wt BCGF-like molecule in vitro. We have studied neoplastic B cells from patients with untreated hairy cell leukemia (HCL) to ascertain whether such cytoplasmic BCGF activity is present in the tumor cells. Studies on HCL cells from four patients indicated that BCGF-like activity was in fact present in the cytosolic extracts when tested on autochthonous HCL cells as well as on normal BCGF-dependent human B cell lines. Chromatographic analysis indicated that the BCGF activity from HCL cells was similar in mol wt as well as function to the normal T cell-derived cytosolic BCGF activity. These studies suggest that HCL cells contain and, in some cases, secrete a high-mol-wt growth factor that can be autostimulatory and appears to resemble a similar growth factor molecule found in normal human T cells.

Growth factor-mediated tumor cell proliferation in hairy cell leukemia

Leukemic B cells from seven patients with hairy cell leukemia (HCL), six of which contained the Tac antigen, were assayed in vitro for growth factor-mediated cell proliferation. The HCL cells showed typical phenotypic profiles by monoclonal antibody analysis. The tumor cells, which do not grow spontaneously in vitro, were found to proliferate in all but one case in response to partially purified B cell growth factor (BCGF) without anti-mu or Sac activation. Recombinant interleukin 2 however produced only a marginal response and could not support leukemic cell growth in vitro. BCGF, however, did stimulate in vitro cell growth and supported the establishment of continuous (greater than 60 d in vitro) in four of the seven HCL cases.

Growth factor-mediated proliferation in B cell non-Hodgkin's lymphomas

The non-Hodgkin's lymphomas (NHLs) are a heterogeneous group of human lymphoid tumors, primarily of B cell lineage, which appear to represent arrested stages in B lymphocyte differentiation. Control of cell proliferation is a fundamentally important but poorly understood area of study in these tumors. We have studied a representative group of B cell NHLs to assess their potential for growth factor-mediated proliferation in vitro. Our results show that purified monoclonal NHL B cells of the small cell (well-differentiated lymphocytic lymphoma, nodular poorly differentiated lymphocytic lymphoma, etc) type, that were positive for the human malignancy-associated nucleolar antigen could be stimulated by human B cell growth factor (BCGF) to proliferate in vitro. Other B cell activators such as insoluble anti-Ig and the mitogen protein A also could stimulate thymidine incorporation in the lymphoma cell populations. In vitro lymphoma cell growth could be maintained in the presence of the growth factor for up to five weeks. The large B cell type NHL, however, appeared to be refractory to in vitro stimulation by BCGF as well as other stimulators of normal B cells. These studies suggest that human B cell lymphoid tumors are not only phenotypically similar to their normal B lymphocyte counterparts, but are also sensitive in some cases, to the same types of immunoregulatory molecules that control normal lymphoid cell growth.

Association of an interleukin abnormality with the T cell defect in Hodgkin's disease

The cellular immune defect in untreated Hodgkin's disease (HD) has long been recognized. This defect appears to be responsible for at least some of the morbidity and ultimately the mortality associated with the disease. In recent years, many studies have shown that the T cell component of the immune response is the apparent site where the defect in HD exists and where the immunoregulatory abnormalities that may account for the deficit are observed. The discovery of the lymphokines and monokines, comprising the human interleukin system, has elucidated some aspects of the regulatory control of the functional pathways involved in T lymphocyte activation and proliferation. The interleukin system can therefore provide the framework to dissect immunodeficiency states, such as that seen in HD. The present study indicates that HD patients' interleukin 1 (IL1) response appears to be normal, as is their T cell proliferative response to exogenous IL2. Interleukin 2 production by HD patients' peripheral blood mononuclear cells, however, is decreased when compared with age/sex-matched controls. The inability to generate IL2 after appropriate stimulation may reflect either a primary cellular defect or a regulatory defect, such as excessive immunosuppression, giving rise to the characteristic T cell hyporesponsiveness seen in HD.

Identification of human lymphoma cells by antisera to malignancy-associated nucleolar antigens

The non-Hodgkin's lymphomas (NHL) are a diverse group of human lymphoid neoplasms that have long presented pathologists with formidable diagnostic challenges. These tumors of the immune system are thought to represent neoplastic transformations of most of the recognized stages in T and B lymphocyte ontogeny. Lymphoma cells, however, often simulate their normal lymphocytic counterparts both morphologically and cell surface phenotypically, creating difficulties in discriminating normal from neoplastic lymphocytes. We have used heteroantisera to the human malignancy-associated nucleolar antigen (HMNA) to prospectively evaluate its efficacy in identifying the morphologically neoplastic cells in NHL lesions. In 65 cases of T and B cell histopathologic types of NHL, the antisera reacted with nucleoli in the morphologically and cytogenetically neoplastic lymphoma cells, but not with normal-appearing lymphoid and other cell types present in the lesions. Control specimens from normal and hyperplastic lymphoid tissue also failed to react with anti-HMNA antibodies. Normal activated lymphoid cells in vitro and growth-factor-dependent normal lymphoid cell lines also failed to express the nucleolar antigen(s). These data suggest that the HMNA is a valuable tumor cell marker for neoplastic human lymphoid cell populations and can be used with other types of cell markers for a better definition of the neoplastic cells in NHL.

Double primary malignancies: osteosarcoma and medulloblastoma

We report the case of an 8 1/2-year-old boy who, after successful treatment for osteosarcoma, had a fatal medulloblastoma. We discuss the possible causes for such an association.

Suppression of lymphocyte responses by monocytes with untreated and treated multiple myeloma

Studies were performed on 15 untreated and 14 treated patients with multiple myeloma. The monocyte content was normal in blood but elevated in mononuclear leukocytes (MNL) from treated but not untreated patients (p less than 0.001). This correlated with the severity of lymphopenia in blood (p less than 0.01). Three patterns of immunoglobulin(Ig) synthesis emerged. (1) Most untreated patients showed normal polyclonal responses to pokeweek mitogen. (2) Of 12 treated patients, the 8 whose MNL included greater than 30% monocytes had subnormal Ig responses to pokeweek mitogen. Ig synthesis increased when adherent cells that suppressed Ig synthesis were depleted. Suppression in vitro bore no relationship to polyclonal immunoglobulin levels in serum. (3) Three patients had early blood invasion by plasmacytoid cells. Their MNL spontaneously released large amounts of the Ig class of their serum gammopathies. Proliferative responses to phytohemagglutinin by MNL from all patients were reduced, in part due to monocytoid cell suppression and in part to intrinsic T-cell hyporesponsiveness. B- and T-cell responses in vitro are sometimes suppressed with myeloma. This is related to elevated monocyte percentages in MNL preparations. This excess of monocytes is a function of lymphopenia secondary to therapy, rather than the primary malignant process itself. No evidence was found that suppression by monocytes is qualitatively altered by myeloma or its treatment.

Growth factors in Hodgkin's disease

Tumor nodules from spleens removed at staging laparotomy for nodular sclerosing Hodgkin's disease were grown as fragment cultures in vitro. These cultures could be maintained in vitro for up to 2 months and consisted of 90% large, adherent multinuclear and mononuclear cells. Immunologic markers and enzyme histochemistry suggested that the cultured cells belonged to the monocyte/macrophage lineage. Supernatants from these cell cultures were then assayed for the monokine Interleukin I and for fibroblast stimulatory factors, which were both present. These results are discussed in considering Hodgkin's disease as a neoplasm of the monocyte/macrophage lineage, capable of producing functionally active mediators that may account for the histopathologic appearance observed.

The characterization of trypan blue-induced tumors in Wistar rats

Trypan blue is an azo dye widely used for testing cell viability. The dye has been identified as a mutagen and a carcinogen. In some strains of rats, particular Wistar rats, chronic exposure induces a reticuloendothelial neoplasm, predominantly in the liver. These tumors were studied with the use of immunologic cell membrane markers, electron microscopy, and histochemistry to characterize tumor cell type. The authors have studied this tumor in two inbred lines of Wistar rats to compare the efficacy of two previously described dye regimens on tumor incidence and to ascertain whether a short, intense exposure was as effective as chronic protracted exposure. No significant difference in tumor incidence was observed between the two regimens. These studies suggest that the tumor is composed of a macrophage-like cell that retains some characteristics of normal macrophages and that is a reproducible model for carcinogen-induced lymphoreticular human lymphomas.

Human T lymphocyte/monocyte interaction in response to lectin: kinetics of entry into the S-phase

PHA-mediated mitogenesis of human peripheral blood T lymphocytes was studied by using highly purified cell populations. The kinetics of human, mature T cell [3H]-Tdr incorporation were examined with respect to those elements necessary and sufficient for the progression of the activated T cell into the S-phase of the cell cycle. These experiments indicated that although a lectin may independently initiate morphologic T cell blastogenesis, this event is not associated with significant progression through the G1 phase of the cell cycle. This blastogenic response is associated with the subsequent T cell receptivity to monocyte-initiated cell cycle progression, and the effect of monocytes can be substituted by partially purified Interleukin 1 (IL-1). Progression of a lectin exposed T cell into the S-phase of the cell cycle could also be achieved by exposing the activated T cell to partially purified Interleukin 2 (IL-2). Given the prior demonstrations that IL-1 functions to induce the T cell-dependent production of the IL-2, it appears that IL-2 is the requisite signal necessary for the activated human lymphocyte to actually progress through the prereplicative phase of the cycle into the S-phase.

Human T lymphocyte/monocyte interaction in response to lectin: kinetics of entry into the S-phase

PHA-mediated mitogenesis of human peripheral blood T lymphocytes was studied by using highly purified cell populations. The kinetics of human, mature T cell [3H]-Tdr incorporation were examined with respect to those elements necessary and sufficient for the progression of the activated T cell into the S-phase of the cell cycle. These experiments indicated that although a lectin may independently initiate morphologic T cell blastogenesis, this event is not associated with significant progression through the G1 phase of the cell cycle. This blastogenic response is associated with the subsequent T cell receptivity to monocyte-initiated cell cycle progression, and the effect of monocytes can be substituted by partially purified Interleukin 1 (IL-1). Progression of a lectin exposed T cell into the S-phase of the cell cycle could also be achieved by exposing the activated T cell to partially purified Interleukin 2 (IL-2). Given the prior demonstrations that IL-1 functions to induce the T cell-dependent production of the IL-2, it appears that IL-2 is the requisite signal necessary for the activated human lymphocyte to actually progress through the prereplicative phase of the cycle into the S-phase.

SJL tumor: a neoplasm involving macrophages

Tumor-bearing lymph nodes from SJL mice were characterized by histologic, ultrastructural, and immunologic methods. These approaches consistently revealed a predominance of macrophage-like cells in the primary neoplasm. When the tumor-bearing lymph nodes were placed in cell culture, colonies of adherent cells grew slowly to confluence and demonstrated morphologic and functional properties of macrophages. The tumor cells were also grown in soft agar where clusters and colonies of large, often binucleate, cells predominated. These cells were uniformly nonspecific esterase-positive, again, suggesting a macrophage origin. In addition, supernatants derived from SJL tumor cells were shown to have mitogen-augmenting activity as tested on murine thymocytes. These findings are discussed in the context of the SJL tumor as a proliferative condition primarily involving macrophages, which may be useful as a model of human diseases such as Hodgkin's disease.

Effect of interleukin 1 on human thymocytes and purified human T cells

Human Interleukin 1 (IL-1) purified by molecular weight fractionation, isoelectric focusing, and gel electrophoresis has been tested on human thymocytes and highly purified human T cells. IL-1 prepared in this manner could not support the long-term growth of T cells yet would augment lectin-stimulated mitogenesis. The IL-1 preparations were shown to possess the lectin-augmenting activity at dilutions containing less than 1 ng of the measurable protein. These data are in agreement with the model that IL-1 stimulates production of IL-2 from lectin-stimulated lymphocytes.

Siderosis of lymph nodes patients with Hodgkin's disease

Lymph nodes removed from 28 untreated patients with Hodgkin's disease all contained markedly increased amounts of hemosiderine, whether or not they were histologically involved in the disease. This finding was particularly striking in patients with the nodular sclerosis type of disease. Abnormal deposits of iron were also noted frequently in lymph nodes containing metastatic carcinoma, lymphoma of non-Hodgkin's type, and reactive hyperplasia, but in each case, with the exception of metastatic squamous cell carcinoma, the amount was significantly less than seen in Hodgkin's disease. The findings suggest that in patients with Hodgkin's disease and perhaps in those with other disorders in which abnormal tissue retention of iron underlies sideropenic anemia, lymph nodes are an important site of iron retention.