EBV-transformed lymphoblastoid cell lines down-regulate EBNA in parallel with secretory differentiation

Four monoclonal and one polyclonal lymphoblastoid cell line (LCL) were studied with regard to cytoplasmic immunoglobulin (cIg) expression, presence of the Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA) and DNA synthesis. Each line was found to consist of two subpopulations, with only minimal overlap. Proliferating, EBNA-positive, cIg-negative cells formed the majority. The minority were EBNA-negative, contained abundant cIg and were largely non-proliferating. This suggests the continuous occurrence of a maturation process within each LCL. The concomitant down-regulation of EBNA raises the interesting question whether continued synthesis of the nuclear antigen is incompatible with differentiation for epigenetic reasons, or, alternatively, whether differentiation takes place when the viral genomes are suppressed or lost.

The Lugano statements on controlled clinical trials

During a consensus conference in Lugano, Switzerland, 175 statements on controlled clinical trials were drafted by 47 representatives from academia, governmental registration agencies and industry in nine countries. Their opinion on these statements was similar to that of 47 'matched pairs' who did not attend the conference. Thus, the opinion of participants and non-participants appears to reflect the general opinion of those currently involved in designing, conducting and analysing controlled clinical trials. The Lugano statements give answers to the following questions: Is the controlled clinical trial in a crisis? What is the motivation to perform controlled clinical trials? Is it possible for a physician participating in a controlled clinical trial to act in the patient's best interest? Is it possible to obtain truly informed consent in a controlled clinical trial? When is it ethical to withhold active treatment in a controlled clinical trial? What are the controversial issues in the design of a good controlled clinical trial? Is there a double standard with respect to efficacy and adverse drug reactions in controlled clinical trials? What are the alternatives to controlled clinical trials and when should they be performed? How can sponsor bias be minimized? How should an ethics committee decide whether a controlled clinical trial is ethical? Should registration agencies become directly involved in the planning and conduct of controlled clinical trials? Do the declarations of Tokyo and Helsinki facilitate the conduct of ethically valid controlled clinical trials? Is it possible to create an international standard for the conduct and regulation of controlled clinical trials? Why do messages from controlled clinical trials filter into medicine so slowly? Is it possible to bridge the gap between controlled clinical trials and clinical reality? What are the costs of doing and not doing controlled clinical trials? When should drug companies decide to start a trial programme with a specific compound? Is there public hostility against controlled clinical trials? If so, how can it be reduced? The respondents almost unanimously felt that controlled clinical trials are a must: the public must be told that progress in medicine depends on controlled clinical trials, that patients often benefit from participating in them and that the alternative, practising in the face of constant uncertainty, is worse than the possible disadvantages related to the conduct of the trial.

Four virally determined nuclear antigens are expressed in Epstein-Barr virus-transformed cells

The expression of Epstein-Barr virus (EBV)-determined antigens associated with growth-transformation of B cells was studied by immunoblotting with human sera from healthy donors. Four antigens were detected in EBV-carrying cell lines and in B lymphocytes early after infection with the transforming B95-8 substrain of virus. They were not found in uninfected cells, nor could they be demonstrated with sera lacking antibodies to EBV antigens. All four antigens were nuclear. Each of them varied in size in the different cell lines. The two antigens with the lowest molecular weight were identified as EBV-determined nuclear antigens (EBNAs) 1 and 2. The two high molecular weight antigens (140-160 kDa and 150-180 kDa, respectively) were detected with 6 of 16 EBV antibody-positive sera. These proteins appeared to be antigenically unrelated to each other and to EBNAs 1 and 2 and were designated EBNAs 3 and 4. Like EBNAs 1 and 2, they bound to double- and single-stranded DNA in vitro.

Production of chemokinetic inhibitory factor (CIF) by normal blood and spleen B lymphocytes

We have recently reported the partial purification and characterization of of a new lymphokine, the heat-labile chemokinetic inhibitory factor (CIF) which inhibits neutrophil movement. We have also shown that this lymphokine is produced and secreted by cultured B-chronic lymphocytic leukaemia (CLL) cells in vitro. The present study shows that highly purified resting normal B lymphocytes from blood and spleen have the capacity to produce CIF spontaneously. After activation with anti-IgM or EBV-infection the lymphocytes produced a number of other factors, heat-stable chemokinetic inhibitory factors and heat-labile chemokinetic enhancing factors. Supernatants from a collection of human B-cell lines representing different stages of B-cell differentiation were also investigated. None of these cell lines produced CIF. The present results show that the production of CIF is not restricted to the malignant B-CLL cell but is also produced by a subset of normal blood and spleen B cells.

Capacity of B-lymphocytic lines of diverse tumor origin to produce and respond to B-cell growth factors: a progression model for B-cell lymphomagenesis

Human cell lines established from cases of acute lymphoblastic leukemia, lymphosarcoma, Burkitt's lymphoma and multiple myeloma and representing stages of B-lymphocyte development ranging from pre-B through to plasma cells, were assessed for their ability to produce and respond to B-cell growth factors (BCGF). All B-cell lines studied were found to be constitutive producers of a growth activity which assisted the S-phase entry of normal activated B-cells and provided growth support for lymphoblastoid cells transformed by Epstein-Barr virus. Furthermore, all lines responded by enhanced proliferation to supernatants from a BCGF-producing T-cell hybridoma. Not all lines, however, displayed autostimulation to their own supernatants and no tumor B-cell line appeared totally dependent on soluble factors for its growth. Non-tumorigenic B-cell lines, by contrast, revealed a strict dependency on homologous growth factor for their continued proliferation in suspension culture. The findings support a progression model of lymphomagenesis based upon the utilization, production and, ultimately, emancipation from growth-promoting soluble factors.

Immunoglobulin gene organization of ultraviolet-illuminated human lymphoblastoid cell lines producing both IgM and IgG

We have studied the immunoglobulin gene organization of ultraviolet light (u.v.)-induced variant cells derived from an Epstein-Barr virus-transformed cell line. One variant produced IgG1 and two variants produced both IgM and IgG1 whereas the parental cell line produced IgM. Southern blot analyses of DNAs of these cells revealed a newly rearranged JH fragment in all the variants. The newly rearranged JH fragment also hybridized with the C gamma 1 sequence. The mu and gamma 1 chains produced in the double isotype-producing variants share the same VH sequence. u.v. illumination also induced rearrangement of the C lambda gene in the IgG1-producing variant. The double isotype producers contained the immunoglobulin gene organization and mutation best explained by fusion of the IgG1 producer and the parental IgM producer.

Epstein-Barr virus induced pneumococcal antibody production in man. A comparison of different lymphoid organs

B cell enriched lymphocytes from different lymphoid organs were compared regarding their ability to produce pneumococcal polysaccharide (PPS) antibodies in vitro after transformation with Epstein-Barr virus. Tonsillar, adenoidal and peripheral blood lymphocytes (PBL) were studied. Fifty thousand B enriched lymphocytes from each organ sample were cultured in each of 88 wells of a microplate. After 30 days the supernatant of each culture was assayed for pneumococcal antibody activity and total IgG and IgM, using enzyme immunosorbent assay. Sera from the organ donors were analysed as well. In the supernatants, significant specific antibody activity was detected only of the IgM class, although IgG production was recorded. The IgM anti-PPS activity of PBL was significantly higher than that of the adenoidal lymphocytes (P less than 0.01), with tonsillar lymphocytes in an intermediate position, although the level of total IgM was of the same magnitude. Sera from children showed the highest IgM anti-PPS activity and at the same time the lowest IgG activity. The opposite relation was recorded in sera from the adult donors. Irrespective of the explanation for different distribution of specifically reactive cells in different lymphoid organs our data indicate distinct compartmentalization of immunocompetent B cell clones.

UV light-induced immunoglobulin heavy-chain class switch in a human lymphoblastoid cell line

During attempts to select nonsecretory variants from 0.467.3, and Epstein-Barr virus-transformed human lymphoblastoid cell line that secretes small amounts of IgM lambda, we exposed the cells to UV light. Cells that survived the irradiation were subcultured and their supernatants were screened for immunoglobulin production by an enzyme-linked immunosorbent assay (ELISA). Although stable nonsecretory variants were not isolated, we report here that an immunoglobulin class switch occurred in the UV-treated cell population. All survivors were found to produce large quantities of IgG lambda. Some cell cultures also produced the original IgM lambda. The UV-light-induced class switch was regularly reproducible with this target cell line.

Enzyme-linked immunosorbent assay for the detection of Epstein-Barr virus-induced antigens and antibodies

Two Epstein-Barr virus (EBV)-specific ELISA tests were developed. One, based on the use of crude extracts from virus producer cells highly induced in the presence of Ara C (providing EA + VCA- cells) or in the absence of the drug (providing EA + VCA + cells) is suitable for the detection of antibodies directed against antigen complexes associated with the lytic virus cycle; i.e., EA, VCA and presumably also MA. The second, performed with purified EBNA, can be used for the detection of antibodies to the transformation-associated nuclear antigen. The tests are expected to find application in the dissection of antibody responses of patients to various antigenic subcomponents, the monitoring of EBV-coded antigens during biochemical purification, and the screening of spent media from hybridoma cultures for EBV-specific antibodies.

Human monoclonal antibodies to a genus-specific chlamydial antigen, produced by EBV-transformed B cells

Stable B cell lines producing human monoclonal antibodies to Chlamydia were established from salpingitis patients in the early convalescence phase. The antibody-producing cells were immortalized by Epstein Barr virus (EBV) transformation. Specific antibody-secreting clones were enriched by a stepwise microtiter plate cloning procedure. The selected B cell clones showed stable antibody production for more than 1 yr in continuous culture. Serologic specificity was demonstrated by micro-immunofluorescence (micro-IF) tests against a panel of Chlamydia reference strains. The antibodies were of the IgG1 subclass, and complement fixation could be demonstrated for one clone. There was no cross-reactivity against a large number of other bacteria. The monoclonal antibodies are directed against a common genus-specific surface antigen of the Chlamydia organism. Infected McCoy cells showed a brilliant, punctuated fluorescence surrounded by an inclusion membrane. Compared with conventional antisera, the monoclonal antibodies showed a clearer fluorescence pattern with very low background.

Human monoclonal antibodies to a genus-specific chlamydial antigen, produced by EBV-transformed B cells

Stable B cell lines producing human monoclonal antibodies to Chlamydia were established from salpingitis patients in the early convalescence phase. The antibody-producing cells were immortalized by Epstein Barr virus (EBV) transformation. Specific antibody-secreting clones were enriched by a stepwise microtiter plate cloning procedure. The selected B cell clones showed stable antibody production for more than 1 yr in continuous culture. Serologic specificity was demonstrated by micro-immunofluorescence (micro-IF) tests against a panel of Chlamydia reference strains. The antibodies were of the IgG1 subclass, and complement fixation could be demonstrated for one clone. There was no cross-reactivity against a large number of other bacteria. The monoclonal antibodies are directed against a common genus-specific surface antigen of the Chlamydia organism. Infected McCoy cells showed a brilliant, punctuated fluorescence surrounded by an inclusion membrane. Compared with conventional antisera, the monoclonal antibodies showed a clearer fluorescence pattern with very low background.

Ab initio calculations of electron distributions in heme-CO models

We have, by the use of ab initio calculations, found a back-bonding state of pi symmetry close to the Fermi level for CO bound to FeN5C14. We thus find it likely that small shifts of the redox potential magnitude of EF - EV magnitude of will cause relatively large changes of the CO vibrational frequency. The separation of Fe 3d orbitals in our heme model is found to agree with what is predicted by ligand field theory for Oh symmetry. This paper presents nonrelativistic Hartree-Fock-Slater calculations of the 5 sigma bonding and 2 pi back-bonding between CO and Fe. The effects of up to 19 additional atoms are discussed for models of heme (COFe to COFeN5C14). The filled back-bonding state is found to be strongly influenced by second nearest neighbor atoms. By use of symmetry orbitals we have resolved the Fe 3d orbitals into the T2g and Eg representations of the Oh point group and find the former states to be occupied whereas the latter are unoccupied. The difference in occupancy is reduced when the CO ligand is removed which also causes an increased density of states at the Fermi level, i.e., the highest occupied and lowest unoccupied orbitals. Possible correlations between our data and experimental results are discussed for heme proteins as well as for metal surfaces.

Monoclonal antibodies against Vibrio cholerae lipopolysaccharide

A cell line producing monoclonal antibodies directed against the core region of Vibrio cholerae lipopolysaccharide has been established. These antibodies were inhibited by lipopolysaccharide preparations of both O-group 1 vibrios and some non-O-group 1 vibrios as detected in enzyme-linked immunosorbent assay-inhibition experiments. Coagglutination experiments with monoclonal and polyclonal antibodies adsorbed to protein A-carrying staphylococci were performed. All V. cholerae strains tested, regardless of serotype, were agglutinated when mixed with staphylococci coated with the monoclonal antibodies, whereas staphylococci coated with group-specific (O1) polyclonal antibodies only agglutinated with O-group 1 vibrios.

A comparative study of metronidazole and sulfasalazine for active Crohn's disease: the cooperative Crohn's disease study in Sweden. II. Result

Seventy-eight patients with active Crohn's disease participated in a randomized, double-blind, cross-over trial. The study comprised two 4-mo period. The purpose was to test the efficacy of metronidazole in comparison with that of sulfasalazine. As the main evaluation criteria the Crohn's Disease Activity Index and plasma levels of orosomucoid were chosen. In the first period no difference in efficacy as measured by Crohn's Disease Activity Index was found between the treatment groups. The reduction of the plasma orosomucoid level was significantly more pronounced in the metronidazole group. The hemoglobin concentration increased more in this group than in the sulfasalazine group, possibly due to a toxic effect of sulfasalazine. The erythrocyte sedimentation rate decreased similarly with both drugs. In 15 patients who had active disease throughout the first period, Crohn's Disease Activity Index decreased significantly in the second period for those who switched to metronidazole, but not for those who switched to sulfasalazine. After crossover, no apparent further change in Crohn's Disease Activity Index occurred in either of the treatment groups among patients who had responded favorably in the first period. The plasma concentration of orosomucoid increased significantly among the patients in the sulfasalazine group but not in the metronidazole group. It is therefore concluded that metronidazole is slightly more effective than sulfasalazine in the treatment of crohn's disease. It is worthwhile switching the drug regimen from sulfasalazine, when it fails, to metronidazole, but not from metronidazole to sulfasalazine.

A comparative study of metronidazole and sulfasalazine for active Crohn's disease: the cooperative Crohn's disease study in Sweden. I. Design and methodologic considerations

The design and execution of the Cooperative Crohn's Disease Study in Sweden are described in this paper. A double-blind, double-dummy, crossover (2 X 4 mo) technique was used to compare the suppressive efficacy of metronidazole (0.4 g b.i.d.) and sulfasalazine (1.5 g b.i.d.). The number of randomized patients (78) presented approximately one-third of the available population. The Crohn's Disease Activity Index and the plasma level of orosomucoid were the main variables for clinical evaluation. Results were analyzed primarily in the first treatment period by ranking the clinical outcome of every patient according to a uniform and detailed scheme and applying Wilcoxon nonparametric statistics. The cross-over data only served as additional information. Thirty-six patients had had earlier and mostly positive experience with sulfasalazine. Repeated plasma drug analysis indicated good compliance. The blindness of the trial was tested and appeared satisfactory. The coordination of the trial proceeded as planned. A lack of full conformity in the electroimmunoassay of orosomucoid was taken care of satisfactorily.

Cimetidine or propantheline combined with antacid therapy for short-term treatment of duodenal ulcer

Seventy-one patients with duodenal ulcer disease completed a 3- to 6-week controlled randomized trial in which cimetidine (1 g daily) was compared with an optimally effective dose of propantheline. Both groups had free access to an antacid suspension. There were no significant differences between the groups concerning ulcer healing, relief of ulcer symptoms, antacid consumption, or patient compliance. After 3 weeks of treatment, endoscopic examination revealed complete ulcer healing in 63% of the cimetidine and 47% of the propantheline treated patients. The corresponding figures after 6 weeks were 94% and 86%, respectively. After 12 weeks, ulcer recurrence was confirmed in 26% of the cimetidine- and 23% of the propantheline-treated patients. Except for the absence of anticholinergic adverse reactions, no significant advantages could be confirmed for combined cimetidine and antacid treatment.

Hybridization of a myeloid leukemia-derived human cell line (K562) with a human Burkitt's lymphoma line (P3HR-1)

The myeloid leukemia-derived Epstein-Barr virus (EBV)-negative human lymphoid cell line K562 was successfully hybridized with the EBV-carrying Burkitt's lymphoma line P3HR-1. Authenticity of the hybrid PUTKO-1 was established by chromosome and isoenzyme studies. A virtually complete hybrid PUTKO-1 carried the EBV genome derived from the lymphoma parent. It averaged 26 EBV DNA copies per cell and was 100% positive for Epstein-Barr virus-associated nuclear antigen (EBNA). In most respects, the hybrid resembled the K562 parent: It had a high Fc receptor concentration, high sensitivity to natural killer cells, absence of EBV C3 receptors, and deficiency of membrane-associated beta 2-microglobulin (beta 2M) and HLA, in parallel with intracellular synthesis and secretion of beta 2M to the medium. Unlike the P3HR-1 parent, the hybrid was completely nonpermissive for antigens of the EBV cycle, early antigen, and viral capsid antigen. None of the 3 inducing agents, 5-lodo-2'-deoxyuridine, 12-O-tetradecanoyl-phorbol 13-acetate, or sodium butyrate, caused any viral antigen synthesis in PUTKO-1 in contrast to the good inducibility of the parental P3HR-1 subline. Thus the myeloid parent restricted expression of EBV antigens except EBNA. This exception further supports the concept that EBNA is an autonomous function of the viral genome, independent of host cell control that regulates expression of antigens related to the viral cycle. On the contrary, extinction of viral antigens in this hybrid between 2 cell lineages supports our previous concept that the ability to produce viral antigens is similar to a differentiated B-cell property.

Characterization of a human ovarian teratocarcinoma-derived cell line

A cell line (PA I), derived from human ovarian teratocarcinoma cells, was obtained by culturing ascitic fluid cells from a patient with recurrence of malignant ovarian teratoma. During early passages the cultured cells showed a variable morphology, a long doubling time, and a low plating efficiency (2%). After about 50 passages in vitro, a cell population which was more homogeneous and resembled embryonal carcinoma cells were obtained. These cells had a shorter doubling time (26 h), and increased plating efficiency (77%). The early-passage cells were aneuploid (P 24) whereas the late-passage cells had a normal diploid karyotype with one balanced translocation between chromosomes No. 15 and No. 20 (P 224). Details of the karyotype suggest that the cells are heterozygous, i.e. derived from a stage before the first meiotic division. One of the two X chromosomes were inactive, and the cells expressed HLA antigens (A28 and B12), and beta 2-microglobulin. Expression of F9 antigen, characteristic of two-cell and later preimplantation embryos, was absent, while expression of PCC4 antigen, expressed also by blastocysts, was present. This finding suggests that the line might express some embryonic characteristics. The PA I cell line maintained in monolayer cultures showed several characteristics of malignant cells. The proportion of malignant cells increased with successive passages in vitro. The late-passage cells represented a fairly homogenous population of malignant cells similar to embryonal carcinoma cells. Late-passage PA I cells, when seeded under conditions that prevented attachment of cells to the substratum, formed embryoid bodies consisting of an inner core of cells similar to embryonal carcinoma cells, surrounded by a rind of endoderm-like cells. These two cell layers were separated by a basement membrane-like structure containing fibronectin. The core embryonal carcinoma cells expressed high alkaline phosphatase activity whereas the endoderm-like cells had low alkaline phosphatase activity. Embryoid bodies seeded on an adhesive substratum formed polycystic structures divided by layers of epithelial-like cells and containing extracellular fibrils similar to collagen type I or III. In these cultures, further limited differentiation into endoderm-like, epithelial-like cells and pigmented cells was observed. Morphological differenciation of undifferentiated PA I cells into endoderm-like cells in monolayer cultures could be obtained by treatment with BrdUrd or by plating in low serum concentration and at low density. Cells with characteristic fibrillar distribution of fibronectin and actin microfilament bundles were then observed, indicating formation of cells lacking properties of malignant cells. As indicated by these results, the PA I cell line, in spite of a limited capacity to differentiate in vitro, shares some of the properties of mouse teratocarcinoma cell lines and might therefore serve as a useful model for studies on some developmental mechanisms in human cells.