High-frequency establishment of human immunoglobulin-producing lymphoblastoid lines from normal and malignant lymphoid tissue and peripheral blood

Presence of Epstein-Barr virus-infected B lymphocytes with thyrotropin receptor antibodies on their surface in Graves' disease patients and in healthy individuals

Graves' disease is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies (TRAbs). Because Epstein-Barr virus (EBV) persists in B cells and is occasionally reactivated, we hypothesized that EBV contributes to TRAbs production in Graves' disease patients by stimulating the TRAbs-producing B cells. In order for EBV to stimulate antibody-producing cells, EBV must be present in those cells but that have not yet been observed. We examined whether EBV-infected (EBV(+)) B cells with TRAbs on their surface (TRAbs(+)) as membrane immunoglobulin were present in peripheral blood of Graves' disease patients. We analyzed cultured or non-cultured peripheral blood mononuclear cells (PBMCs) from 13 patients and 11 healthy controls by flow-cytometry and confocal laser microscopy, and confirmed all cultured PBMCs from 8 patients really had TRAbs(+) EBV(+) double positive cells. We unexpectedly detected TRAbs(+) cells in all healthy controls, and TRAbs(+) EBV(+) double positive cells in all cultured PBMC from eight healthy controls. The frequency of TRAbs(+) cells in cultured PBMCs was significantly higher in patients than in controls (p = 0.021). In this study, we indicated the presence of EBV-infected B lymphocytes with TRAbs on their surface, a possible player of the production of excessive TRAbs, the causative autoantibody for Graves' disease. This is a basic evidence for our hypothesis that EBV contributes to TRAbs production in Graves' disease patients. Our results further suggest that healthy controls have the potential for TRAbs production. This gives us an important insight into the pathogenesis of Graves' disease.

The dispersal of mucosal memory B cells: evidence from persistent EBV infection

We have used latent infection with the human herpesvirus Epstein-Barr virus to track the dispersal of memory B cells from the mucosal lymphoid tissue of Waldeyer's ring (tonsils/adenoids). EBV is evenly distributed between the memory compartments of Waldeyer's ring and the peripheral blood. However, it has an approximately 20-fold higher preference for Waldeyer's ring over the spleen or mesenteric lymph nodes. These observations are consistent with a model whereby the virus preferentially establishes persistent infection within memory B cells from Waldeyer's ring. The virus then colonizes the entire peripheral lymphoid system, at a low level, by trafficking with these memory B cells as they circulate through the body and back to Waldeyer's ring. This pathway may reflect that of normal memory B cells derived from nasopharyngeal and other mucosal lymph nodes.

Immunotherapeutic strategies for EBV-associated malignancies

Advances in our understanding of the role of cytotoxic T lymphocytes (CTLs) in the control of Epstein-Barr virus (EBV)-associated malignancies and the overall biology of these diseases have led to the development of novel therapeutic strategies designed to specifically target viral antigens expressed in these malignancies. Long-term success of many of these strategies is constrained by the latency phenotypes adopted by different diseases. Adoptive transfer of polyclonal virus-specific CTLs has been used successfully to reverse the outgrowth of malignancies such as post-transplant lymphoproliferative disease (PTLD). On the other hand, limited viral gene expression in other EBV-associated malignancies such as Burkitt's lymphoma, Hodgkin's disease and nasopharyngeal carcinoma limits the efficacy of immunotherapeutic strategies used for PTLD. Preclinical studies based on specific targeting of viral antigens expressed in these malignancies have provided very encouraging results and thus are likely to serve as an important platform for the treatment of human patients.

Regulation of human cell engraftment and development of EBV-related lymphoproliferative disorders in Hu-PBL-scid mice

Human PBMC engraft in mice homozygous for the severe combined immunodeficiency (Prkdcscid) mutation (Hu-PBL-scid mice). Hu-PBL-NOD-scid mice generate 5- to 10-fold higher levels of human cells than do Hu-PBL-C.B-17-scid mice, and Hu-PBL-NOD-scid beta2-microglobulin-null (NOD-scid-B2mnull) mice support even higher levels of engraftment, particularly CD4+ T cells. The basis for increased engraftment of human PBMC and the functional capabilities of these cells in NOD-scid and NOD-scid-B2mnull mice are unknown. We now report that human cell proliferation in NOD-scid mice increased after in vivo depletion of NK cells. Human cell engraftment depended on CD4+ cells and required CD40-CD154 interaction, but engrafted CD4+ cells rapidly became nonresponsive to anti-CD3 Ab stimulation. Depletion of human CD8+ cells led to increased human CD4+ and CD20+ cell engraftment and increased levels of human Ig. We further document that Hu-PBL-NOD-scid mice are resistant to development of human EBV-related lymphoproliferative disorders. These disorders, however, develop rapidly following depletion of human CD8+ cells and are prevented by re-engraftment of CD8+ T cells. These data demonstrate that 1) murine NK cells regulate human cell engraftment in scid recipients; 2) human CD4+ cells are required for human CD8+ cell engraftment; and 3) once engrafted, human CD8+ cells regulate human CD4+ and CD20+ cell expansion, Ig levels, and outgrowth of EBV-related lymphoproliferative disorders. We propose that the Hu-PBL-NOD-scid model is suitable for the in vivo analysis of immunoregulatory interactions between human CD4+ and CD8+ cells.

Epstein-Barr virus genomes are found predominantly in IgA-positive B cells in the blood of healthy carriers

B lymphocytes have been identified as the main reservoir of latent Epstein-Barr virus (EBV) in healthy virus carriers. We have established a semi-quantitative PCR method to estimate the EBV genome load in the blood B-cell subpopulation in healthy individuals. EBV DNA was detected in subfractionated IgM-, IgG- and IgA-positive B cells. Between 80% and 90% of the viral DNA was found in the IgA-positive compared with the IgA-negative fraction.

Enhanced frequency of spontaneous B cell lines from Epstein-Barr virus (EBV) seropositive donors 80 years and older

Based on the well-recognized decline in immunocompetence which develops with advancing age, we have evaluated the effect of age on the frequency of development of spontaneous Epstein-Barr virus (EBV)-infected B cell lines. Blood mononuclear cells were isolated from 38 clinically healthy seropositive donors. The cells were maintained in vitro according to routine culture conditions for lymphocytes. Eight spontaneously EBV-infected B lymphoblastoid cell lines (LCL) were isolated. The LCL developed in 12.5, 14.3, or 6.3% of the samples derived from donors in the three age groups 20-39, 40-59, 60-79, respectively. In contrast, samples from five of seven (71%) donors 80 years and older yielded LCL. Although the reason(s) for the increased frequency of occurrence of spontaneous LCL from the older adults is yet to be explored, the possible role of the virus-specific T lymphocytes as a contributing factor is discussed.

Detection of Epstein-Barr virus genomes in normal human lacrimal glands

Epstein-Barr virus (EBV) has been implicated in several ocular diseases; however, detection of the EBV genome in ocular tissues has not been documented. We report the detection of amplified EBV genomic sequences in 11 of 26 normal lacrimal gland DNA samples by using the polymerase chain reaction. Serum was available for 19 of the lacrimal gland donors. All 19 were EBV seropositive, although of the 19 lacrimal gland-seropositive patients, EBV sequences were detected in only 10 of the samples. Further, amplified EBV sequences were not detected in circulating lymphocyte DNA from normal seropositive volunteers, most likely because of the low frequency of circulating EBV-infected B cells. Amplification of EBV from cadaver lacrimal gland DNA was possible with minute quantities of DNA, whereas peripheral blood mononuclear cell DNA from normal volunteers did not amplify EBV sequences. Interestingly, the peripheral blood mononuclear cell polymerase chain reactions contained approximately 100 times more DNA than the lacrimal gland polymerase chain reactions. We conclude that the lacrimal gland may be a site for EBV persistence and that positive EBV serology is not an indicator of which individuals may have EBV harbored within their lacrimal glands.

Replication of latent Epstein-Barr virus genomes in normal and malignant lymphoid cells

DNA replication of 2 human lymphoid cell lines (U296 and Raji), latently infected with the Epstein-Barr virus, has been compared using a density transfer approach. Typical of non-malignant lymphoblastoid cells, U296 cells divided once in bromodeoxyuridine-supplemented medium to form hybrid but not heavy-density host DNA. Replication of the intracellular Epstein-Barr virus DNA was selectively inhibited in these cells with only 15% of the viral genomes duplicating once to form hybrid-density viral DNA. However, some heavy-density viral DNA was formed in the U296 cells and DNA synthesis can thus initiate again on newly duplicated viral genomes in cells that have traversed only a single S phase. These results contrast strongly with observations concerning the Burkitt-lymphoma-derived cell line. Lymphoma cells are not growth-inhibited and most of the latent Epstein-Barr virus genomes of the Raji line replicated once, and only once, in successive S phases. While the majority of the 50 Epstein-Barr virus genomes of both the Raji and U296 cell lines are maintained as extra-chromosomal DNA plasmids, the control of their duplication is distinctly different in the respective malignant and non-malignant host cells.

Human acute lymphoblastic leukemia cell lines with characteristics of intraclonal variation in B-cell differentiation stage

The acute lymphoblastic cell lines designated BAL-KHc and BAL-KHs were established from the peripheral blood of a Japanese female patient with a B-cell acute lymphoblastic leukemia. The BAL-KHc and BAL-KHs exhibited B-cell characteristics with positive cell markers for CD19, CD20, CD21 and HLA-DR antigens. Immunoglobulin with gamma and kappa chains was demonstrated on the cultured and fresh leukemia cells respectively. The cells lacked the Epstein-Barr virus genome and expressed abnormal chromosome constitutions including a t(8;14)(q24;q32). These results suggested that the cell lines present B-cell characteristics. The BAL-KHc cells showed different cell growth characteristics and cell surface marker profile compared to those of the BAL-KHs. These variations suggest that the BAL-KHc cells were probably frozen at a different stage of B-cell maturation from those of BAL-KHs, although both cell lines originated from the cells in the same peripheral blood sample of the patient.

Establishment and characterization of a human lymphoma cell line (WSU-NHL) with 14;18 translocation

The WSU-NHL cell line was established from a malignant pleural effusion occurring in a 46-yr-old female with nodular histiocytic (follicular, large cell) lymphoma. The established cells grow in clumps with a doubling time of 57 h. On light microscopy, cells exhibited primitive lymphoblastoid morphologic features with few cytoplasmic blebs. DNA histogram generated by flow cytometry indicated a hypodiploid stemline (0.93). Immunologic study revealed a mature B-cell phenotype with surface and cytoplasmic IgG lambda and reactivity with monoclonal antibodies to B-cell antigens (B1, B4, BL1, BL3, BL4, BL7, HLA-DR, CALLA and Leu-10). The cells were negative for T-cell and myeloid-monocyte antigens as well as Epstein-Barr virus nuclear antigen (EBNA). Cytogenetic analysis revealed 45,XX metaphases with complex abnormalities including t(14;18) (q32;q21). The phorbol ester, 12-O tetradecanoylphorbol 13 acetate (TPA) (1.6 x 10(-8) M) and interferon gamma (IFN-gamma) (500 U/ml) inhibited cell growth and induced differentiation to a more mature phenotype. The WSU-NHL cell line provides a continuous source of cells for molecular and immunologic studies of human lymphoma as well as the regulation of its growth and differentiation by biologic agents.

Characterization of EBV-carrying B-cell populations in healthy seropositive individuals with regard to density, release of transforming virus and spontaneous outgrowth

Peripheral or tonsil lymphocyte populations of EBV-seropositive donors give rise to EBV-carrying LCLs upon in vitro explantation. Such lines can arise either by a 2-step mechanism, namely release of virus from some of the explanted cells followed by infection of previously uninfected B cells, or by direct outgrowth of virus-harboring B cells (Rickinson et al., 1974; Dalens et al., 1975; Hinuma and Katsuki 1978; Katsuki et al., 1979). We observed that cells responsible for both the 2-step mechanism and for direct outgrowth are found in the purified B-cell compartment. Virus release was more frequent than direct outgrowth. The majority of virus-releasing cells were found in the low-density fraction that contains large, activated B blasts. Cells that were capable of spontaneous outgrowth in the presence of the viral inhibitor PFA and of virus-neutralizing antibody gave rise to cell lines that carried the sex chromosome marker of the original donor, rather than that of admixed cord blood lymphocyte of the opposite sex. Such cells were found in both the low- and the high-density fractions. The majority of the EBV-carrying B cells in vivo are thus low-density blasts. Rare small B cells of high density harboring EBV were capable of spontaneous outgrowth. This may be indicative of a host control mechanism that is removed upon cultivation in vitro.

Mapping genetic elements of Epstein-Barr virus that facilitate extrachromosomal persistence of Epstein-Barr virus-derived plasmids in human cells

The Epstein-Barr virus (EBV) genome becomes established as a multicopy plasmid in the nucleus of infected B lymphocytes. A cis-acting DNA sequence previously described within the BamHI-C fragment of the EBV genome (J. Yates, N. Warren, D. Reisman, and B. Sugden, Proc. Natl. Acad. Sci. USA 81:3806-3810, 1984) allows stable extrachromosomal plasmid maintenance in latently infected cells, but not in EBV-negative cells. In agreement with the findings of Yates et al., deletion analysis permitted the assignment of this function to a 2,208-base-pair region (nucleotides 7315 to 9517 of the B95-8 strain of EBV) of the BamHI-C fragment that contained a striking repetitive sequence and an extended region of dyad symmetry. A recombinant vector, p410+, was constructed which carried the BamHI-K fragment (nucleotides 107565 to 112625 of the B95-8 strain, encoding the EBV-associated nuclear antigen EBNA-1), the cis-acting sequence from the BamHI-C fragment, and a dominant selectable marker gene encoding G-418 resistance in animal cells. After being transfected into HeLa cells, this plasmid persisted extrachromosomally at a low copy number, with no detectable rearrangements or deletions. Two mutations in the BamHI-K-derived portion of p410+, a large in-frame deletion and a linker insertion frameshift mutation, both of which alter the carboxy-terminal portion of EBNA-1, destroyed the ability of the plasmid to persist extrachromosomally in HeLa cells. A small in-frame deletion and linker insertion mutation in the region encoding the carboxy-terminal portion of EBNA-1, which replaced 19 amino acid codons with 2, had no effect on the maintenance of p410+ in HeLa cells. These observations indicate that EBNA-1, in combination with a cis-acting sequence in the BamHI-C fragment, is in part responsible for extrachromosomal EBV-derived plasmid maintenance in HeLa cells. Two additional activities have been localized to the BamHI-C DNA fragment: (i) a DNA sequence that could functionally substitute for the simian virus 40 enhancer and promoter elements controlling the expression of G-418 resistance and (ii) a DNA sequence which, although not sufficient to allow extrachromosomal plasmid maintenance, enhanced the frequency of transformation to G-418 resistance in EBV-positive (but not EBV-negative) cells. These findings suggest that the BamHI-C fragment contains a lymphoid-specific or EBV-inducible promoter or enhancer element or both.

Nucleotide sequences of mRNAs encoding Epstein-Barr virus nuclear proteins: a probable transcriptional initiation site

Three cDNA clones of the second Epstein-Barr virus nuclear antigen (EBNA2) mRNA and two of the EBNA1 mRNA were analyzed. Two EBNA2 clones begin 42 bases 3' to a promoter in the Epstein-Barr virus long internal repeat, which is likely to be the EBNA2 promoter. Surprisingly, the first splice creates an AUG at the beginning of the first of two nonoverlapping open reading frames. The second open reading frame encodes EBNA2. Two incomplete EBNA1 mRNA cDNA clones begin with parts of two of the EBNA2 exons and contain two other exons that map 19 and 59 kilobases 3' to the EBNA2 coding domain. The 3' exon of this mRNA encodes EBNA1. A model for regulation of transcription of these RNAs is presented.

Protoporphyrinogen oxidase and porphobilinogen deaminase in variegate porphyria

Two enzymes of the haem biosynthetic pathway were investigated in patients with variegate porphyria. Protoporphyrinogen oxidase in cultures of Epstein-Barr virus transformed lymphoblasts from twenty-seven patients showed a mean maximal velocity (Vmax) of 0.39 +/- 0.08+ nmol of protoporphyrin mg protein-1 h-1, a 52% reduction (P less than 0.001) from a non-porphyric control group (0.82 +/- 0.10). Km values (1.00 +/- 0.27 microM) did not differ significantly (P greater than 0.05) from control values in any of the patients. The mean Vmax of porphobilinogen deaminase in the cultures was 1.50 +/- 0.18 nmol of uroporphyrin mg protein-1 min-1, a 24% reduction (P less than 0.001) from controls (1.94 +/- 0.14). Mean porphobilinogen deaminase activity in the erythrocytes of twenty-one patients with variegate porphyria was 8.37 +/- 1.99 nmol of uroporphyrin 1 erythrocytes-1 s-1, a 28% reduction (P less than 0.001) from normal (11.98 +/- 2.11). The reduced activities of these two enzymes comply with the expression of variegate porphyria during its quiescent and acute phases.

Orientation and patching of the latent infection membrane protein encoded by Epstein-Barr virus

Epstein-Barr virus is known to encode three nuclear proteins and one membrane protein (LMP) in latently infected growth-transformed cells. Studies of the plasma membrane localization and orientation of LMP by protease digestion of live cells and by immunofluorescence indicated the following. (i) At least 30% of LMP is in the plasma membrane, as opposed to other cytoplasmic membranes. (ii) A small LMP domain which corresponds to a previously proposed outer reverse turn between the first two transmembrane domains is exposed on the outer cell surface (and two other proposed outer-reverse-turn domains may be exposed), whereas all or almost all of the rest of the protein is not exposed on the outer cell surface. (iii) LMP is present in patches in the cell plasma membrane.

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.

Mapping genetic elements of Epstein-Barr virus that facilitate extrachromosomal persistence of Epstein-Barr virus-derived plasmids in human cells

The Epstein-Barr virus (EBV) genome becomes established as a multicopy plasmid in the nucleus of infected B lymphocytes. A cis-acting DNA sequence previously described within the BamHI-C fragment of the EBV genome (J. Yates, N. Warren, D. Reisman, and B. Sugden, Proc. Natl. Acad. Sci. USA 81:3806-3810, 1984) allows stable extrachromosomal plasmid maintenance in latently infected cells, but not in EBV-negative cells. In agreement with the findings of Yates et al., deletion analysis permitted the assignment of this function to a 2,208-base-pair region (nucleotides 7315 to 9517 of the B95-8 strain of EBV) of the BamHI-C fragment that contained a striking repetitive sequence and an extended region of dyad symmetry. A recombinant vector, p410+, was constructed which carried the BamHI-K fragment (nucleotides 107565 to 112625 of the B95-8 strain, encoding the EBV-associated nuclear antigen EBNA-1), the cis-acting sequence from the BamHI-C fragment, and a dominant selectable marker gene encoding G-418 resistance in animal cells. After being transfected into HeLa cells, this plasmid persisted extrachromosomally at a low copy number, with no detectable rearrangements or deletions. Two mutations in the BamHI-K-derived portion of p410+, a large in-frame deletion and a linker insertion frameshift mutation, both of which alter the carboxy-terminal portion of EBNA-1, destroyed the ability of the plasmid to persist extrachromosomally in HeLa cells. A small in-frame deletion and linker insertion mutation in the region encoding the carboxy-terminal portion of EBNA-1, which replaced 19 amino acid codons with 2, had no effect on the maintenance of p410+ in HeLa cells. These observations indicate that EBNA-1, in combination with a cis-acting sequence in the BamHI-C fragment, is in part responsible for extrachromosomal EBV-derived plasmid maintenance in HeLa cells. Two additional activities have been localized to the BamHI-C DNA fragment: (i) a DNA sequence that could functionally substitute for the simian virus 40 enhancer and promoter elements controlling the expression of G-418 resistance and (ii) a DNA sequence which, although not sufficient to allow extrachromosomal plasmid maintenance, enhanced the frequency of transformation to G-418 resistance in EBV-positive (but not EBV-negative) cells. These findings suggest that the BamHI-C fragment contains a lymphoid-specific or EBV-inducible promoter or enhancer element or both.

Effect of human recombinant alpha-2- and gamma-interferon on the growth of human cell lines from solid tumors and hematologic malignancies

We studied the growth effects of human recombinant interferon (IFN)-alpha-2 and -gamma on various human cell lines. Four cell lines from solid tumors (WiDr, CCL 185, BT 20, KB) and three cell lines from hematologic malignancies (U 937, U 266, MOLT 4) were chosen. The study was performed using two different assays: (1) a soft agar cloning assay, and (2) a monolayer and suspension culture. In the soft agar assay alpha-IFN inhibited colony growth of 6/6 lines tested (the line MOLT 4 could not be plated); in the monolayer assay it inhibited proliferation of 6/7 lines tested. Gamma-IFN showed inhibitory effects on 5/6 cell lines tested in the soft agar assay, but on one line (CCL 185) low concentrations of gamma-IFN led to a significant increase in the number of colonies. Using the monolayer assay, gamma-IFN showed inhibition of 6/7 lines tested, whereas a stimulation of growth could not be observed. With a combination of alpha- and gamma-IFN, synergistic effects were seen on a histiocytic cell line (U 937) in both assays and a marginal synergism on the T-cell line MOLT 4 in the monolayer assay.

Phenotypic and cytogenetic characteristics of a new Epstein-Barr virus negative cell line (SKW 4) derived from a B-cell lymphoma

A new Epstein-Barr virus nuclear antigen (EBNA) negative cell line SKW 4 has been established in vitro from a patient with diffuse histiocytic lymphoma. The SKW 4 seems to be an authentic human tumour cell line as evidenced by its EBV negativity, monoclonality and aneuploidy tested during early in vitro passage. The cell line expresses surface mu and kappa-chains, HLA-DR antigen, C3 and Fc receptors and B-cell lineage antigens. The karyotypic analyses demonstrated many numerical and structural aberrations. No Burkitt lymphoma associated translocations (t8;14, t2;8, t;22) were detected, but most of the markers found are those commonly associated with various types of human cancer. The SKW 4 thus represents the most common type of 'histiocytic lymphoma', that with a B-lymphoid cell phenotype, but is unique among HL derived lymphoma lines in its strong expression of a Helix pomatia A agglutinin binding surface glycoprotein of an apparent molecular weight of 75 000 daltons.

Formation and growth of multicellular spheroids of human origin

Different types of human cells which normally grow as monolayers or suspension cultures were tested for their capacity to form and grow as spheroids. Sixteen out of the 27 tested tumour cell lines formed spheroids. Nearly all of these spheroids also grew. With only two exceptions the doubling times were longer when the tumour cells grew as spheroids than when they grew in conventional mass culture. Eleven out of 13 tested human non-tumour cells formed small spheroids but of these only the spheroids of lymphoid origin could grow. These lymphoid cells grew faster when aggregated to spheroids than when in single-cell suspension culture. None of the other non-tumour cells, which normally grew as monolayers, could grow as spheroids. The normally monolayer-cultured tumour cells formed symmetrical spheroids with smooth surfaces while the normally suspension-cultured cells formed irregular spheroids with rough surfaces. All large spheroids had a necrotic centre surrounded by a shell of viable cells. The thickness of the viable cell layer varied depending on cell type. The shape and organization of cells within the spheroids also varied largely. The results show that many types of human cells can be cultured as spheroids and that a wide spectrum of morphological appearances and growth rates can be obtained.

Establishment and characterization of a human non-secretory plasmacytoid cell line and its hybridization with human B cells

A human non-secretory plasmacytoid cell line has been established for 6 years in more than 170 passages. Over 300 passages have been made from several early and late passages. The cell line is karyotypically normal, easily grown and has the characteristic features of a non-secretory plasmablast. Its characteristics suggest its use for hybridization by new methods as well as a study of its secretory defect. HPRT-negative phenotypic mutants can be derived from this line and a single polyploid clone has also been isolated. Hybridization with the HPRT+ and HPRT- lines X human B cells is described.

Similar repair of O6-methylguanine in normal and ataxia-telangiectasia fibroblast strains. Deficient repair capacity of lymphoblastoid cell lines does not reflect a genetic polymorphism

The ability of human fibroblast strains to repair the mutagenic DNA adduct O6-methylguanine (O6-MeG) induced by brief exposure to N-methyl-N'-nitroso-N-nitrosoguanidine (MNNG) was investigated. The repair reaction proceeded rapidly during the first hour after alkylation, followed by a slow, continuous phase of repair, and both processes were saturated by low doses of carcinogen. This was similar to what had previously been found in human lymphoblastoid lines. Three fibroblast strains from healthy donors and six strains from patients with ataxia telangiectasia were all proficient in their capacity to repair O6-MeG and had the same sensitivity to the cytotoxicity of MNNG and methyl methanesulphonate as normal cells. Three of these cell strains were derived from individuals whose lymphoblastoid lines were deficient in their ability to repair O6-MeG. These lymphoblastoid lines were also extremely hypersensitive to killing by methylating carcinogens. Because non-transformed cells from the same donors behaved normally with regard to both parameters, we concluded that the repair deficiency accompanied by carcinogen hypersensitivity of the lymphoblastoid lines does not indicate a genetic deficiency in the donor. These findings imply that lymphoblastoid lines may not always be the appropriate cell type for investigating genetic susceptibility to chemical mutagens.

Establishment and characterization of two neoplastic cell lines (U-1285 and U-1568) derived from small cell carcinoma of the lung

Two human cell lines have been established in vitro from patients with small cell carcinoma of the lung (SCC). The U-1285 line was derived from the classical small cell type of SCC while the U-1568 originated from a larger cell variant. The cell lines grow as suspension cultures and have been passaged continuously in vitro for 3 years (U-1285) and 2 years (U-1568), respectively. The malignant nature of the lines is suggested by their infinite growth potential, their capacity to form colonies in agarose and their aneuploidy. Both cell lines contain cytoplasmic electron dense particles indistinguishable from classical neurosecretory granules but only in U-1568 has hormone production (human chorion gonadotropin (alpha-HCG)) been proven. The U-1568 line produces carcino-embryonic antigen (CEA) while both U-1285 and U-1568 produce alpha-feto-protein (AFP). Chromosome analysis reveal aneuploidy of both lines. Among structural aberrations, involvement of chromosome 14 in U-1285 and chromosomes 1, 7 and 12 in U-1568 is interesting since alterations of these chromosomes have been described previously in other malignant conditions.

Lysis of human B-lymphocyte-derived lymphoma/leukemia cells of established cell lines by interferon-activated natural killer (NK) cells

Cultured cell lines derived from malignant Epstein-Barr virus (EBV)-negative B cells, and representative of the more common types of naturally occurring non-Hodgkin lymphomas and related leukemias, were found to be sensitive to lysis by human natural killer (NK) cells. The observed lysis of such cell lines was mediated by a population of interferon-augmentable, FcR-positive, non-adherent lymphoid cells, which were also able to kill the "standard" NK targets K562 and Molt-4. When the NK susceptibility of the neoplastic, EBV-negative B cells was compared to that of diploid, EBV-carrying, non-neoplastic B lymphoblastoid cell lines (BLCLs) and of the "standard" NK target K562, several distinct patterns were observed. The killing of the neoplastic B cell lines was significantly less than that of K562, but significantly greater than that of the EBV-derived BLCLs of non-neoplastic origin. An additional finding was a similar NK susceptibility profile for the neoplastic, true histiocytic cell line U-937 (i.e., K562 greater than U937 greater than BLCLs). Furthermore, all cell lines, with the exception of the BLCLs, could effectively compete for the observed killing in cold target inhibition assays. The implications of these findings are discussed in relation to both neoplastic and non-neoplastic targets of NK lysis.

Establishment of attached and non-attached cell lines from an uncommon human glioma

A New cell line, U-706, established from an uncommon human glioma (possibly giant-cell glioblastoma) is reported in this communication. The tumor gave rise to two permanent sublines, one attached (U-706M) and one non-attached (U-706S) cell line. The growth characteristics, chromosome banding pattern, electronmicroscopic picture and cell surface characteristics of the two sublines are described.

TEM and SEM findings in cat fibroblasts cultivated in vitro with and without Mycoplasma

Mycoplasma contamination of cultured cells may cause considerable interference with their behaviour and metabolism. Whether or not mycoplasma are actually taken up by cells in vitro has long been a matter of dispute. In the present study mycoplasma were shown to phagocytosed by feline lung fibroblasts and to end up in the lysosomal vacuome of the cells, where the organisms were only partially degraded by the hydrolytic enzymes leading to a rapid (within a few days) accumulation of secondary lysosomes of the residual body variety. It is thus obvious that studies on the structure and function of the lysosomal vacuome in cultured cells are possible only if precautions are taken to avoid that the cultures become contaminated by mycoplasma.

Two neoplastic cell lines with unique features derived from Hodgkin's disease

Two in vitro cell lines (L428, L439) were established from pleural effusions of two patients with Hodgkin's disease. The histological diagnosis was ascertained in both cases by two independent pathologists. The neoplastic nature of the culture cells is indicated by the demonstration of several structural and numerical chromosome abnormalities associated with a monoclonal pattern of marker chromosomes. Heterotransplantation in nude mice was achieved by intracranial inoculation and by subcutaneous transplantation of cultured cells embedded in a plasma clot. EBV-specific antigens (EBNA, VCA) were not detectable in either cell line. Ia-like antigens, receptors for T cells, acid phosphatase and acid esterase were shown to be present in the cultured cells. The L428 and L439 cell line lacked surface- or cytoplasmic Ig, HTLA, receptors for C3b, C3d, IgG-Fc, mouse E or sheep E, and were devoid of lysozyme, peroxidase and chloracetate esterase. These features do not correspond to those of B cells, T cells, myeloid cells, monocytes or macrophages; the morphology and the marker pattern of the culture cells, however, is identical with that of freshly obtained Hodgkin (H)- and Sternberg-Reed (SR)- cells, except for the lack of Clg in the in vitro cells, which is explained by the culture conditions. These findings suggest that the L428 and L439 cell lines are indeed derived from H- and SR-cells and offer the possibility of gaining new information upon the nature of Hodgkin's disease.

The establishment of a cell line (NH-AR) from a human nodular lymphoma and a comparison with lymphoblastoid cell line

A cell line (NH-AR strain) has been established in vitro from a patient with malignant lymphoma, nodular histiocytic type, and maintained in continuous growth for more than 18 months. The cells grew floating in the culture medium forming characteristic balls. The doubling time of the total cell population was 38.4 hours. Surface and cytoplasmic immunoglobulin synthesis were monoclonal gamma heavy chain and lambda light chain. Chromosome analysis of the cell line revealed 47/48,XY,+A with a mode of 47,XY,+1,1p-,t(2q-;3pt+),t(18q-;14q+), which was identical to that obtained from the biopsied lymph node. Ultrastructurally, tight interdigitation of the cytoplasmic processes was reminiscent of the labyrinthine structure of the nodular lymphoma cells. Its nodular growth pattern is discussed in relation to other lymphoblastoid cell lines.

Establishment of a lymphoid cell line from leukemic cells of a patient with chronic lymphocytic leukemia

Two lymphoid cell lines were established from a patient with chronic lymphocytic leukemia by infecting blood cells with Epstein-Barr virus (EBV). Studies of morphology, glucose-6-phosphate dehydrogenase, malic enzyme, immunoglobulin, and chromosomes of the two lines indicated that one of them originated from leukemic cells while the other arose from residual normal blood cells. The morphology and capacity for immunoglobulin secretion in the line that arose from leukemic cells were similar to those found in EVB-carrying lymphoblastoid cell lines grown from patients without neoplasia and differed from those seen in fresh chronic lymphocytic leukemia cells. These observations suggest that the introduction of EBV into the leukemic cells may have caused them to differentiate in a fashion similar to that noted in normal B cells after exposure to EBV.

Epstein-Barr virus RNA. V. Viral RNA in a restringently infected, growth-transformed cell line

A continuous lymphoblastoid cell line, IB-4, was established by infection and growth transformation of normal neonatal B lymphocytes with the B95-8 isolate of Epstein-Barr virus (EBV). The IB-4 cells contained the intranuclear antigen, EBNA, but not early antigen, EA. The fragments produced by the digestion of intracellular episomal viral DNA (density, 1.700 to 1.720 g/cm3) with EcoRI restriction endonuclease were identical in size to the A, B, C, E, F, G, and H fragments of virion DNA. As expected from the previous observation that episomal intracellular DNA is circular, the fragment containing the rightward terminal sequences of EBV DNA in IB-4 cells was larger than the corresponding fragment of linear viral DNA, probably as a consequence of covalent linkage to the leftward terminal fragment. Also, two fragments, EcoRI-I and -J, which were adjacent to each other in the virion DNA, were absent from the intracellular DNA. The labeled EcoRI-J of viral DNA hybridized instead to a new fragment equal in size to EcoRI-I and -J combined. Analysis of viral RNA in IB-4 cells showed that RNAs encoded by more than 30% of the viral DNA comprised approximately 0.06% of the nuclear RNA, whereas RNAs encoded by 20% and 10% of the viral DNA comprised approximately 0.06% and 0.003% of the polyadenylated and polyribosomal RNAs, respectively. Viral mRNA (polyribosomal RNA) was encoded by DNA which mapped at 0.05 x 10(8) to 0.36 x 10(8) daltons and to a lesser extent by DNAs which mapped at 0.62 x 10(8) to 0.67 x 10(8), 0.70 x 10(8) to 0.73 x 10(8), and 1.13 x 10(8) to 1.15 x 10(8) daltons in the B95-8 genome. The most agundant nuclear viral RNAs were encoded primarily by DNA which mapped at the same loci; but RNAs encoded by many other fragments of viral DNA could also be detected among nuclear RNAs. Viral mRNA(s) (polyribosomal) was encoded by about 40% of the internal reiteration and by 25% of the BamHI-H fragments which mapped from 0.32 x 10(8) to 0.36 x 10(8) daltons, nuclear RNAs were encoded by at least 57% of the internal reiteration and 40% of BamHI-H. These data indicate that there is selective accumulation of some viral RNAs within the nucleus of IB-4 cells and that there is selective post-transcriptional processing of these RNAs. Finer mapping of the DNA which encodes mRNA (polyribosomal) in IB-4 cells indicated that some of this DNA is deleted in the DNA of the P3 HR-1 virus, the only isolate of EBV which cannot initiate growth transformation. These data, therefore, support the hypothesis that expression of this region of EBV genome is important for growth transformation or for the maintenance of restrigent infection.

Production of human IgM anti-D in tissue culture by EB-virus-transformed lymphocytes

Lymphocytes obtained from two donors who were producing anti-D were transformed with Epstein-Barr virus and grown in tissue culture. The lymphoblasts from both donors produced anti-D antibody, which agglutinated Rh-positive cells in saline. Both antibodies belonged to the IgM class; the concentration of anti-D in the culture fluid from one of the donors was approximately 250--500 ng/ml and bound firmly to Rh-positive cells with a functional affinity constant of approximately 1 x 10(9) M-1.

Isozymes of amino acid naphthylamidase in human haematopoietic cell lines

The occurrence of isozymes of the proteolytic enzyme amino acid naphthylamidase was investigated in a panel of 44 neoplastic and non-neoplastic haematopoietic cell lines by polyacrylamide gel electrophoresis. Two isozymes (A and C) were common for all lines, whereas different forms of a third isozyme with intermediate electrophoretic mobility (B) appeared in nine lines. Isozyme A seemed to be associated with cell proliferation and was not a marker for malignancy. The appearance of different B isozymes not present in normal peripheral blood lymphocytes, occurred in some Burkitt lymphoma lines and in two non-malignant lines maintained for a long time in culture. In three lines derived from myeloid leukaemia a variant of isozyme B seemed to be a marker for cell origin.

Activation of suppressor T cells during Epstein-Barr-virus-induced infectious mononucleosis

Infectious mononucleosis is caused by the Epstein-Barr virus (EBV), an unusual human pathogen because it preferentially infects B lymphocytes and consequently activates them to produce immunoglobulins. When cultures of lymphocytes from patients with infectious mononucleosis were stimulated with polyclonal activators, unseparated cells failed to produce immunoglobulins, whereas purified B cells responded normally. Cocultures demonstrated profound suppressor T-cell activity in blood from patients with infectious mononucleosis. Early in this disease, circulating immunoglobulin-secreting cells were elevated, but during the second week their number was strikingly depressed. These data indicate that during infectious mononucleosis, EBV causes polyclonal activation of B cells, reflected by hypergammaglobulinemia and increased circulating immunoglobulin-secreting cells. Next, suppressor T cells become activated and inhibit further B-cell activation. Thus, activation of suppressor T cells in infectious mononucleosis provides a unique additional mechanism of host defense because these T cells inhibit the activation and proliferation of an important target of the causative virus.

Herpesviruses

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Growth of diploid, Epstein-Barr virus-carrying human lymphoblastoid cell lines heterotransplanted into nude mice under immunologically privileged conditions

Human Epstein-Barr virus-carrying lymphoid cell lines which have 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 were inoculated intracerebrally into nude mice. All eighteen of them grew, killing the host mice within 7 to 25 days, except for 2 which grew more slowly. At autopsy, the brain of the nudes was found to be invaded by infiltrating lymphomas. Sixteen of these lymphomas, when recultured in vitro, gave rise to cell lines with growth properties and morphology indistinguishable from those of the inoculated LCL. Chromosomal examinations showed that 3/7 cell lines injected, which grew as lymphomas in the brain, were still normal diploid on reexplantation whereas the remaining four had become aneuploid. Four lines derived from intracerebral lymphomas (2 diploid, 1 aneuploid and 1 untested) were inoculated subcutaneously into adult nude mice. None of them grew. When the corresponding four original LCL lines were inoculated subcutaneously into newborn nude mice, they grew rapidly, but failed to do so in newborn normal mice or intracerebrally in adult normal mice. One such line, U-1450, was treated with anti-lymphocyte serum (ALS). Small nodules developed at the site of inoculation. From one nodule a cell line was cultured, 1450 ALSAD. It was morphologically indistinguishable from the line of origin. The lines obtained from nude mice inoculated with polyclonal LCL seem to have a restricted clonal representation, but were not monoclonal, as evidenced by analyses of their pattern of immunoglobulin synthesis.

Cell surface glycoprotein changes in Epstein-Barr virus-positive and -negative human hematopoietic cell lines

It has previously been shown that differential fucose labelling of many normal and homologous tumor cells, followed by proteolytic release and degradation, yields glycopeptides which upon gel filtration shown an increase in fast-eluting glycopeptides for the tumor cells. This technique has now been applied to cell-surface glycoproteins of different human hematopoietic cell lines. These lines included Epstein-Barr virus (EBV)-carrying lymphoblastoid cell lines of presumed non-neoplastic origin, and malignant EBV-genome-positive Burkitt lymphoma and EBV-negative non-Burkitt lymphoma, leukemia and myeloma lines. As compared with normal peripheral lymphocytes, both the lymphoblastoid type of cell lines and the different types of lines of proven malignant ancestry contained the fast-eluting glycopeptides on their cell surface with very few exceptions. It is therefore concluded that (I) malignant conversion of human lymphoid cell in vivo is commonly, but not obligatorily, associated with a specific change in the composition of the fucosyl glycopeptides, and (2) EBV infection of B lymphocytes does not lead only to the well-documented immortalization in vitro but also, as a rule, to the same type of alteration in fucosyl glycopeptides as was demonstrated for the neoplastic cell lines. It proved possible to distinguish several categories of hematopoietic cell lines due to the effect that pretreatment of the glycopeptides with neuraminidase or mild acid exerted on their subsequent chromatographic behavior.

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

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