EBNA-positive Cells Research Articles

B-CLL cells with unusual properties.

In studies concerning the interaction of B-CLL cells and Epstein-Barr virus (EBV), we encountered one patient whose cells had several unusual properties. In addition to the B-cell markers, the CLL cells expressed the exclusive T-cell markers CD3 and CD8 and carried a translocation t(18,22)(q21;q11), involving the bcl-2 and Ig lambda loci. The patient represents the 4th reported CLL case with this translocation. The CLL cells could be infected and immortalized by the indigenous and by the prototype B958 virus in vitro. The T-cell markers were not detectable on the established lines. In all experiments the immortalized lines originated from the CLL cells. Their preferential emergence over virus-infected normal B cells may be coupled to the high expression of the bcl-2 gene due to the translocation. In spite of the sensitivity of CLL cells to EBV infection in vitro, no EBNA-positive cells were detected in the ex vivo population. In vitro, we could generate cytotoxic function in T-lymphocyte cultures which acted on autologous EBV-infected CLL cells. Therefore we assume that if such cells emerged in vivo they were eliminated by the T-cell response.

Detection of two epstein‐barr‐virus (EBV)‐carrying leukemic cell clones in a patient with chronic lymphocytic leukemia (CLL)

The leukemic-cell population of one CLL patient, PG, was found to contain a sub-set of EBV-genome-carrying cells. It was detected directly by the expression of EBNA (EBV-encoded nuclear antigen) and by its capacity to grow in vitro. The proportion of EBNA-positive cells (0.1%) was maintained constantly during the period of this study, the final 3 years of the patient's life. EBV-carrying clonal sibling B-cell lines were established on 5 occasions. They had identically rearranged JH bands and chromosomal markers corresponding to the ex vivo CLL cells. Analysis of the viral episomes in the lines proved that they were the descendants of one cell. On the last occasion of blood sampling, 8 B-cell lines were established; 4 of these contained the same clonal markers as the previous lines, while 4 other lines belonged to another clone with identical JH rearrangement. Their abnormal karyotypes were different from the first clone. The chromosomal markers were only partly identical, suggesting secondary diversifications. The EBV sub-strain carried by this group of lines was different from the sub-strain of the first clone, as judged by the EBNA size distributions (EBNOtype) and EBV-DNA analysis. Analysis of the terminal repeat in the viral episomes also showed that the first and the second set of clones represented 2 independent EBV-infection events in vivo.

Analysis of Viral Gene Expression and Genome Persistence in CD23-Positive and -Negative Subpopulations of Epstein-Barr-Virus-lnfected BL2 Cells

Epstein-Barr virus (EBV) infection of the EBV-negative Burkitt lymphoma (BL) cell line BL2 has been studied in vitro, to assess the efficiency of stable infection and the state of the viral genome in these cells. Expression of the EBV nuclear antigen complex (EBNA 1-6) was detected by 24 h post-infection, but expression of the latent membrane protein (LMP) and of the B cell activation antigen CD23 were delayed until 8 days post-infection, and were then only detectable in a subpopulation of EBNA-positive cells. Separation of cells into CD23-positive and -negative fractions 8 days after infection showed that the CD23-positive cells expressed EBNA 1-6 and LMP and contained viral episomes, whereas the CD23-negative cells were EBNA 1-6 positive, LMP negative and had very low levels of episomal viral genome. Cloning of the CD23-positive and -negative populations showed that EBV infection in the majority of clones was lost, with only 29 out of the 164 investigated still EBNA positive after 6 months of culture. Stable infection correlated with expression of EBNA 1-6, LMP, CD23 and the presence of viral episomes. One clone stably expressed EBNA 1-6 and LMP in the absence of detectable linear or episomal viral genome; this clone was assumed to have a viral genome integrated into the cellular chromosomes. Thus integration of the viral genome following in vitro infection of BL2 cells is a rare event.

Cell phenotype (CD23)-dependent variation in EBV genome copy numbers within lymphoblastoid cell lines (LCL).

Three Epstein-Barr-virus-transformed lymphoblastoid cell lines (LCL) were analysed on the basis of their CD23 expression. Levels of EBV-DNA were compared in the positive and negative subpopulations. Two lines were further analysed with regard to EBNA, cytoplasmic immunoglobulin (cIg) and lytic (EA/VCA) protein expression. Both subpopulations had a similar MHC class-II transcription, but the CD23- subpopulation had a lower plating efficiency and a lower rate of DNA synthesis. In the B6, NAD50 and 0467.3 cell lines, CD23- cells contained 2 +/- 0.2 - 6.4 +/- 3.0 times less EBV DNA than the corresponding CD23+ population. EBNA was expressed in 81 +/- 4.2% - 93 +/- 3.8% of the CD23+ cells and in 0 - 46 +/- 8.0% of the CD23- cells. No CD23+ cells in B6 or NAD50 contained any EA/VCA, while 19 +/- 2.8% - 24 +/- 4.2% of the CD23- cells were positive for the lytic-cycle-associated antigens. Of the CD23- cells, 70 +/- 8.6% - 86 +/- 6.0% were positive for cytoplasmic immunoglobulin compared to 14.7 +/- 2.7% - 14.9 +/- 1.8% in the corresponding CD23+ population. We have previously shown that only 18% of the cIg-positive cells were EBNA-positive in the B6 line compared to 94% in the cIg- population. This was open to 2 alternative interpretations: loss of EBV genomes from a fraction of the cells with subsequent differentiation to secretory immunoglobulin production, or down-regulation of EBNA expression in differentiating, EBV-genome-positive cells. Our present findings speak for the first alternative, indicating that a certain proportion of the cells may lose their EBV genomes in both long-established and freshly transformed LCLs. This is accompanied by a reduced percentage of EBNA-positive cells, the disappearance of at least one activation marker (CD23) associated with the virally induced blast transformation, and an increased synthesis of cIg.

Detection of Epstein-Barr Virus Genome in Benign Polyclonal Proliferative T Cells of a Young Male Patient

Epstein-Barr virus (EBV) DNA was detected in polyclonal T cells that proliferated transiently in a 21-year-old male (referred to as H.J.) who underwent an apparently benign lymphocytosis (white blood cells, 31 x 10(6)/microL; lymphocyte, 79%) with fever, tonsillar swelling, lymphadenopathy, and hepatosplenomegaly. The symptoms and signs subsided mostly within a month of hospitalization. The major population of the lymphocytes at admission was positive for CD3, CD8 (4/8 ratio, 0.16), WT31, and DR antigen. Eight percent of the leukocytes were too blastoid to be classified as atypical lymphocytes of infectious mononucleosis (IM). The blastoid lymphocytes and the duration and degree of the lymphocytosis and hypergammaglobulinemia appeared inconsistent with IM, whereas the EBV serology indicated either EBV primary infection or a secondary alteration of normal seropositive EBV immunity. The genomic analysis of T-cell receptor beta chain in the peripheral blood mononuclear cells (PBMC) at admission with a C beta probe did not show a monoclonal rearrangement. EBV genome was detected in these cells, using the BamHI W and K probe, but not in the cells after discharge. Analysis of the EBV terminal repeat junctional sequence, using Xho I fragment of the latent membrane protein (LMP) probe binding with the terminus, did not show monoclonal or oligoclonal populations. EBV-associated nuclear antigen (EBNA) was detected in 36% of the PBMC at admission, but not in the later cells. These EBNA-positive cells were found to form rosette with sheep erythrocytes. The PBMC of six acute IM patients contained neither EBV DNA nor EBNA-positive cells. The observations in this case show a unique type of EBV infection in T cells that has not been previously reported.

Nachweis des Epstein-Barr-Virus in Tonsillen bei infektiöser Mononukleose

Tonsils of 50 patients with infectious mononucleosis were examined for the presence of Epstein-Barr virus nuclear antigens (EBNA) and in 11 cases for the presence of Epstein-Barr virus (EBV) nucleic acid sequences. In tonsillar tissue of 42 patients less than 1 to 40 per cent EBNA-positive cells could be demonstrated by anticomplement immunofluorescence. 10 out of 11 tonsils examined by in situ hybridization contained less than 1 to 50 per cent cells with EBV nucleic acid sequences. The histological examination indicated that cells labelled by in situ hybridisation are in the majority proliferating B-lymphocytes and to a small extent cells of tonsillar epithelium.

T lymphocytes in infectious mononucleosis; Effect of IL‐2 on the outgrowth of Epstein‐Barr virus‐infected cells

The addition of interleukin-2 (IL-2) to lymphocyte cultures from acute infectious mononucleosis (IM) donors dramatically increased the incidence of regression in such cultures and resulted in the emergence of an IL-2 dependent, CD3 Epstein-Barr virus nuclear antigen (EBNA)-negative cell population. Corresponding cultures seeded in the absence of IL-2 rarely regressed and were quickly dominated by IL-2 independent, CD3-negative, EBNA-positive cells. Lymphocyte cultures from Epstein-Barr virus (EBV) seropositive donors showed enhanced regression in the presence of IL-2 but failed to regress after the removal of the E-rosetting population. Cultures from EBV-seronegative donors showed no evidence of regression in the presence or absence of IL-2. E-rosetting cells isolated from cultures from acute IM donors that had been cultured in the presence of IL-2 lysed autologous and allogeneic lymphoblastoid cell lines.

Interferon-gamma in a family with X-linked lymphoproliferative syndrome with acute Epstein-Barr virus infection

A 20-month-old male with fulminant infectious mononucleosis and the X-linked lymphoproliferative syndrome (XLP) was studied. Epstein-Barr virus (EBV)-determined nuclear antigen (EBNA) and EBV DNA were detected in various tissues. Despite a combined treatment with acyclovir, immunoglobulin, and methylprednisolone, the patient deteriorated rapidly. Following treatment with recombinant interferon-gamma (IFN-gamma), defervescence occurred and circulating EBNA-positive cells markedly decreased. IFN-gamma prior to treatment ranged from 10.8 to 24.5 U/ml in the patient's serum and increased linearly post exogenous IFN-gamma treatment. His natural killer (NK)-cell activity remained in the normal range throughout his illness but autologous EBV-infected cells were not killed in vitro by his peripheral blood lymphocytes (PBL). These results suggest that patients with the fatal infectious mononucleosis phenotype of XLP may produce endogenous IFN-gamma. Defective cytotoxic T cells against EBV-infected cells seem to be responsible for the fulminant infectious mononucleosis in this patient.

Defective cell-mediated response to EBV-transformed B cells in a healthy individual with regular EBV antibody titers.

We have analyzed the EBV-related immune parameters of a healthy EBV-seropositive individual (ST) who has regular antibody titers but defective inhibitory capacity toward the growth of autologous EBV-infected B cells. This in vitro function reflects the EBV-specific memory because it does not occur in experiments performed with cells of seronegative individuals. An analysis of events following in vitro EBV infection showed that lymphocytes of ST behaved in some tests in the same way as those collected from seronegative individuals. These parameters were: lack of gamma-IFN production 24 hr after EBV infection; low production of soluble factors that inhibit EBV-induced B-cell proliferation; lack of generation of LCL selective cytotoxicity after repeated stimulation with autologous LCL; and high proportion of EBNA-positive cells in 7-day-old EBV-infected cultures. On the other hand, cellular memory to the virus detected by the production of IL-2 24 hr after infection, and by the production of LIF upon exposure to EBV-encoded antigens, conformed with the results obtained with seropositive individuals. T-cell-mediated inhibition of EBV-induced B-cell growth in vitro has been regarded as a corollary of in vivo control of EBV-infected B cells. However, it is absent or has a low efficiency in certain disease categories which are not accompanied by risk of B-EBV growth. Our results with a healthy individual also indicate that several mechanisms contribute to a harmless life-long virus carrier state.

Attachment of Antinuclear Antibodies to Nasopharyngeal Carcinoma or Other Cells During Preparation of Biopsy Imprints<xref ref-type="fn" rid="FN2">2</xref>

The presence of Epstein-Barr virus (EBV) genomes in nasopharyngeal and other carcinomas or Burkitt's and other B-cell lymphomas can be established by the demonstration of viral nucleic acid sequences in DNA extracts from biopsy specimens, the detection of EBV-associated nuclear antigen (EBNA) in biopsy imprints, and the inhibition of leukocyte migration by tumor extracts. Of these techniques, the detection of EBNA-positive tumor cells can be performed most readily in the laboratory. This report shows that a patient's antibodies to nuclear antigens can gain access to cell nuclei during the preparation of imprints. If the antibodies are directed against EBNA, nuclear immunofluorescence is elicited solely in the tumor cells when only complement (C') and fluorescein-labeled antibodies to C' are applied to the imprints without prior exposure to anti-EBNA-positive sera. If nonspecific antinuclear antibodies (ANA) are involved, the nuclear immunofluorescence seen in the EBNA-specific and control assays is not limited to the tumor cells but extends to any normal cells that may be present in the imprints. Furthermore, nuclear fluorescence is elicited when solely an anti-human IgG conjugate is applied because ANA is measurable by indirect immunofluorescence, whereas detection of EBNA requires augmentation of the antigen-antibody complexes by C', which differentiates further between EBNA-specific and nonspecific staining. Attachment of antibodies to nuclei can be avoided by minimizing the deposit of blood during imprint preparation and by rapid drying of the imprints. Similar results are obtained experimentally when smears of lymphoblasts are made in the presence of anti-EBNA or ANA.

In-vitro infection of chronic lymphocytic leukemia cells by Epstein-Barr Virus (EBV)

We sought to determine the potential of infecting lymphoid cells from patients with chronic leukemia (CLL) with Epstein-Barr virus (EBV) by testing for EBV receptors (EBVR) by flow cytometry, assessing for infectability of these cells by culturing with B95-8-derived virus, and staining for EB nuclear-associated antigens (EBNA) at various times post-infection. EBVR were present on 54–91% of lymphoid cells in seven cases of CLL and on 46% of prolymphocytic leukemia cells. Dynamic changes regarding EBNA positivity, morphology, and viability occured post-infection with the virus. On day 2 only a few EBNA-positive lymphoblasts were observed. On days 11–21 positivity increased from 2 to 34% of cells. Simultaneously, the viable cell number declined to approximately 1/10th of original number. A significant proportion of the EBNApositive cells corresponded to the original CLL cells. In 3 of 7 cases of CLL a Pan T-cell phenotype was demonstrated by Leu-1 monoclonal antibody testing. The infected cells did not react with two monoclonal antibodies, EBV-CS 1 and 4, which react with B-cell lymphoblastoid cell lines (B-LCL). Moreover, the B-LCL derived at 1–2 months post-infection of CLL cells did not express the Leu-1 antigen, but expressed EBV-CS 1 or 4 defined antigens. In the prolymphocytic leukemia, 64% of the cells showed EBNA positivity on day 7 and giant cells with huge round or multiple nuclei appeared which were EBNA-postive. CLL and prolymphocytic leukemia cells can be infected as demonstrated by EBNA-positivity. This infection does not lead to immediate transformation, but evokes lymphoblast and multinucleated giant cell production prior to the death of cells.

Establishment and characterization of an Epstein-Barr virus nuclear antigen-negative hairy cell line.

Continuous cell lines have been established from spleen cells of patients with confirmed hairy cell leukemia (HCL). One cell line, HCL-Z1, lacks Epstein-Barr virus nuclear antigen (EBNA), grows attached to the substratum and retains typical features of hairy cells as revealed by transmission and scanning electron microscopy. HCL-Z1 differs morphologically from the three other EBNA-positive lymphoblastoid cell lines obtained (HCL-Z2, HCL-Z3, HCL-Z4) as well as from normal spleen cells or lymphocytes. The three lymphoblastoid cell lines derived from HCL patients show similar surface features as a line from a myeloma patient. Therefore, not all cell lines derived from HCL patients may be considered as representative of the patients leukemia cells.

Catalogue of Epstein-Barr virus (EBV) receptors on human malignant and non-malignant hematopoietic cell lines

Epstein-Barr virus (EBV) can induce a broad spectrum of hematological diseases, especially in immune deficient patients. We assayed for receptor for EBV (EBVR) using fluoresceinated viral particles on 44 human hematopoietic cell lines derived from patients with T, B, and non-T, non-B acute lymphocytic leukemia (ALL), non-lymphoid leukemia, Burkitt lymphoma, myeloma and several unique lines we and others have recently developed. All 31 EBV nuclear-associated antigen (EBNA) negative cell lines were of neoplastic origin. Seven of 13 EBNA-positive cell lines were of normal cell origin. Four of 25 non-B (surface immunoglobulin negative) EBNA-negative neoplastic cell lines were EBVR-positive. Three of six EBNA-negative B-cell (surface immunoglobulin positive) lines were EBVR-positive. Nine of 13 EBNA-positive Burkitt and non-Burkitt cell lines strongly expressed EBVR. Four EBNA-positive Burkitt lymphoma cell lines exhibited EBVR only to a limited degree. Studies of the cell lines for EBVR, complement receptors (CR) and surface immunoglobulin (SIg) revealed that presence of SIg does not obligate the presence of EBVR. Functional EBVR accompanied SIg among EBNA-negative cell lines. SIg-negative cell lines can possess EBVR. Fourteen of 16 EBVR-positive lines were also positive for CR. The EBVR assay is a useful tool for assessing the potential role of EBV in the induction of hematopoietic disorders.

Interferon induction in human leukocytes after in vitro exposure to cytomegalovirus or Epstein-Barr virus.

Interferon (IFN) was produced after exposure of human mononuclear leukocytes and bone marrow cells to infectious or noninfectious cytomegalovirus (CMV) in vitro. The IFN was generated mainly by non-B lymphocytes. Both alpha- and gamma-type IFN could be demonstrated. CMV antigens were usually not demonstrable in CMV-exposed leukocytes. Addition of anti-IFN antibodies did not induce CMV antigens. Thus, it seems that the endogenous production of IFN is not responsible for the difficulties in demonstrating CMV antigens after in vitro exposure of normal human leukocytes to CMV. Addition of Epstein-Barr virus (EBV) B95-8 to leukocytes induced the production of alpha-type IFN. Exogenously added IFN reduced the induction of EBV-determined nuclear antigen (EBNA). However, the presence of anti-IFN antibodies in EBV-infected cultures did not increase the number of EBNA-positive cells.

Homosexual men in London: lymphadenopathy, immune status, and Epstein-Barr virus infection.

By November 7, 1983, 24 cases of AIDS in the United Kingdom had been reported to the Communicable Disease Surveillance Centre. At the same time an increasing number of homosexual men with unexplained lymphadenopathy syndrome (LAS) have been seen in our department. Between December 1982 and July 1983, 14 homosexual men with LAS and 11 healthy homosexual men were studied. Patients with LAS had a high number of lifetime episodes of sexually transmitted diseases, a history of recent sexual activity in the United States (9 of 14), sexual contact with British AIDS patients or other persons with LAS (7 of 14), and hypergammaglobulinemia. Low T-helper/T-suppressor ratios (less than 0.8), due mainly to a decrease in T-helper cells, were found in both groups. Lymph node biopsies showed follicular hyperplasia and hypocellular pattern. All 25 patients studied had antibodies to Epstein-Barr virus capsid antigen (anti-VCA) and 11 had antibodies to early antigen (anti-EA); 13 of 17 were excreting the virus; and two showed no Epstein-Barr-virus-specific regression. Peripheral blood immunoglobulin-producing B-cells from six patients with hypergammaglobulinemia were negative for the Epstein-Barr virus nuclear antigen (EBNA). Five lymph node biopsies showed no EBNA-positive cells. Epstein-Barr virus reactivation is common in the patients with LAS and healthy homosexual men in London, but would not seem to be the cause of the polyclonal B-cell activation or lymphadenopathy.

Identification and characterization of a cellular protein that cross-reacts with the Epstein-Barr virus nuclear antigen.

A 62,000-dalton (62K) cell protein reacts with antisera to the 72K polypeptide of the Epstein-Barr virus nuclear antigen (EBNA) in immunoblots. This protein was initially detected in EBNA-negative as well as EBNA-positive cell lines with anti-EBNA-positive human sera. A monoclonal antibody raised against the 72K EBNA and an antiserum from a rabbit immunized with the glycine-alanine domain of EBNA also reacted with the cellular protein. The cellular protein was partially purified from Epstein-Barr virus genome-positive and -negative cell lines. Absorption experiments identified a shared antigenic determinant between the 72K EBNA and 62K cellular protein. A comparison of the 62K protein and EBNA by protease digestion did not reveal similar peptides.

Epstein-barr virus-specific serodiagnostic tests in carcinomas of the head and neck

Sera from 256 patients with cancers of the head and neck were examined for their profiles of IgG and IgA antibodies to Epstein-Barr virus (EBV)-specific, viral capsid antigen (VCA), the diffuse (D) and the restricted (R) components of the early antigen (EA) complex, and the EBV-associated nuclear antigen (EBNA), in order to assess the value of these procedures in the routine diagnosis of poorly or undifferentiated nasopharyngeal carcinoma (NPC). In 13 NPC patients, the carcinoma had invaded cervical lymph nodes, and their sera revealed, in addition to high IgG anti-VCA titers, elevated levels of IgA antibodies to VCA, of IgG antibodies to D, and most also had IgA anti-D. Such profiles were seen in very few of the patients with carcinomas at other sites of the head and neck. They had not developed in four NPC patients whose tumors were limited to the postnasal space, and in three patients with other tumors at that site. Among 15 patients with cervical node metastases from occult primary tumors, 2 had EBV-specific antibody profiles compatible with NPC, 1 was judged to have NPC on clinical grounds, and the other died of a pulmonary carcinoma, or possibly pulmonary metastases. In 4 of the remaining 13 patients with occult tumors, the primary site was found outside the nasopharynx, whereas it escaped detection in the other 9. These results lend further support to the usefulness of the EBV-specific serology to clinicians in the diagnosis of NPC, especially in cases of lymph node invasion by undetected primary tumors. The data also emphasize the need of complementing the serology with the examination of biopsies for the presence of EBV deoxyribonucleic acid (DNA) or, more readily performed, EBNA-positive carcinoma cells.

Restrictions upon Epstein-Barr virus infection of the leukemic cell are demonstrated in patients with hairy cell leukemia.

We tested the hypothesis that Epstein-Barr virus (EBV) might actually infect leukemic hairy cells in vivo by examining those cells for the EBV-receptor, EBV nuclear antigen (EBNA) and membrane antigen (MA), for spontaneous transformation and rescue of infectious virus and for presence of EBV genome. EBV-receptors were found on subpopulations of leukemic cells from each of 7 patients with hairy cell leukemia (HCL) tested. MA was present on low numbers (1-5 per cent) of fresh leukemic cells of 7 patients and in some instances occurred with a greater frequency after 3 to 5 days in culture, with or without 12-O-tetradecanoylphorbol-13-acetate. In 11 fresh leukemic cell preparations from 8 HCL patients, no EBNA was demonstrated. However, 2 samples after 4 days in culture expressed low frequencies of EBNA-positive cells. Spontaneous, EBV-positive cell lines were established with a high transformation efficiency from 3 HCL blood samples but not from 8 other specimens. Infectious EBV could be rescued from some hairy leukemic cell preparations by co-cultivation with cord blood lymphocytes. These results demonstrated that leukemic cell populations harbored infectious EBV, that the leukemic cells expressed virus receptors and suggested that a small subpopulation of leukemic cells might become infected in vivo at least transiently and possibly transformed in vitro by EBV. To test for the extent of occult in vivo infection of leukemic cells with EBV, Southern type hybridization studies were performed with a probe for EBV genome (Bam HI W). At a sensitivity level of 0.1 genome per cell, EBV genome was not detected in the leukemic cell populations of 7 patients. We conclude that host defence mechanisms protecting these individuals from EBV also prevent infections of the leukemic cell and/or most hairy leukemic cells are not suitable targets for both infection and transformation.

Relationship between Epstein-Barr virus nuclear antigen and DNA genome number in superinfected and induced lymphoblastoid cell lines.

The relative contents of Epstein-Barr virus (EBV)-associated nuclear antigen (EBNA) and average numbers of EBV genome equivalents per cell were determined (i) in Raji cells superinfected with P3HR-1 virus, (ii) in Raji cells induced by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and sodium n-butyrate and (iii) in P3HR-1 cells induced by TPA and sodium n-butyrate. This treatment was followed by increases in the percentage of early antigen (in both Raji and P3HR-1 cells) and virus capsid antigen-positive cells (in P3HR-1 cells) and increases of approximately 20-fold in the average number of EBV DNA equivalents in superinfected Raji cells and in TPA- and sodium n-butyrate-induced P3HR-1 cells. However, the content of EBNA in these cells dropped. This was revealed by a decrease in both the complement-fixing antigen content and in the proportion of EBNA-positive cells as determined by anti-complement immunofluorescence. Thus, the positive correlation found previously between the content of EBNA and the number of EBV genome equivalents per cell in proliferating lymphoblastoid cultures does not seem to apply to the situation in either superinfected Raji cells or in P3HR-1 cells induced by TPA and sodium n-butyrate.

Classification of cell lines derived from undifferentiated lymphomas according to their expression of complement and Epstein-Barr virus receptors: Implications for the relationship between African and American Burkitt's lymphoma

Twenty-seven cell lines derived from undifferentiated lymphomas of Burkitt's and non-Burkitt's type, 26 of which possess the 8:14 chromosome translocation, have been characterized with regard to their expression of complement and Epstein-Barr virus (EBV) receptors and their susceptibility to theophylline-induced modification of receptor expression. The cell lines fall into six groups, three EBV nuclear antigen (EBNA) negative and three EBNA positive. The three EBNA-negative groups appear to represent different stages of differentiation—the first in which EBV to complement receptors are not expressed and cannot be induced, a second in which low levels of both receptors are expressed and induction of higher levels can be achieved with theophylline, and a third in which high levels of complement and EBV receptors are already present. EBNA-positive cell lines are either virus producers or virus nonproducers. Nonproducer lines fall into two groups which are distinguished by their degree of expression of complement receptor. The difference between the groups is particularly well shown by their ability of bind FBC at different temperatures (37 and 0.5°C). EBV producer lines express low levels of both EBV and complement receptors. These data suggest that tumors diagnosed histologically as undifferentiated lymphoma are neoplastic counterparts not of a single cell type, but of a spectrum of cell types, although together these cell types represent only a small part of the B-lymphocyte differentiation sequence. Whether individual tumors contain uniform cell population or cells at different stages of differentiation remains to be determined, but African and American tumors are primarily distinguished by their respectively low and high levels of expression of EBV and complement receptors.