Binding of the O-antigen of Shigella dysenteriae type 1 and 26 related synthetic fragments to a monoclonal IgM antibody

Shigella dysenteriae type 1 possesses an O-antigen whose repeating unit is -->3)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->2)-alpha-D-Galp -(1-->3)-alpha-D- GlcpNAc-(1-->, where Rhap is rhamnopyranosyl, Galp is galactopyranosyl, and Glcp is glucopyranosyl. Using ligand-induced protein fluorescence change, we have measured the affinities of a monoclonal murine IgM for 26 fragments of, or related to, the structure of the O-polysaccharide and of the IgM Fab for the intact O-specific bacterial polysaccharide. Synthetic saccharides used were methyl glycosides to ensure an anomerically defined pyranosyl ring conformation. The galactosyl residue is the only monosaccharide of the antigenic epitope that shows quantifiable binding: approximately 3.0 kcal/mol of binding free energy, depending on the structure and conformation of the fragment it is a part of. Addition of an alpha-(1-->2)-linked rhamnosyl residue increases the free energy of binding significantly. We propose this rhamnopyranosyl-alpha-(1-->2)-galactopyranosyl disaccharide to be the basic determinant of the Shigella O-polysaccharide. Further extension (by linkages as in the natural antigen) of this oligosaccharidic ligand toward the upstream end (in an oligo- (or poly-)saccharide, such as A-->B-->C-->D-->E-->m, where A, B, C, D, and E are sugars and m is any moiety, such as methyl, we define A as the glycosyl- or upstream terminus, and E as the glycoside- or downstream terminus) by rhamnosyl and N-acetylglucosaminyl moieties improves the binding only minimally. The antibody is quite specific for the rhamnosyl-alpha-(1-->2)-galactosyl sequence but less so for the nature of the attachment to the galactosyl residue on the downstream side. Measurements using IgM Fab and the intact O-specific polysaccharide show that the antibody can bind internal segments on the antigen chain. The free energy of binding of this antibody for the disaccharide determinant varies from -delta G of 4.7 to 5.1 kcal/mol, depending on its flanking residues.

Acute leukemias of different lineages have similar MLL gene fusions encoding related chimeric proteins resulting from chromosomal translocation

The MLL gene, on human chromosome 11q23, undergoes chromosomal translocation in acute leukemias, resulting in gene fusion with AF4 (chromosome 4) and ENL (chromosome 19). We report here translocation of MLL with nine different chromosomes and two paracentric chromosome 11 deletions in early B cell, B- or T-cell lineage, or nonlymphocytic acute leukemias. The mRNA translocation junction from 22 t(4;11) patients, including six adult leukemias, and nine t(11;19) tumors reveals a remarkable conservation of breakpoints within MLL, AF4, or ENL genes, irrespective of tumor phenotype. Typically, the breakpoints are upstream of the zinc-finger region of MLL, and deletion of this region can accompany translocation, supporting the der(11) chromosome as the important component in leukemogenesis. Partial sequence of a fusion between MLL and the AFX1 gene from chromosome X shows the latter to be rich in Ser/Pro codons, like the ENL mRNA. These data suggest that the heterogeneous 11q23 abnormalities might cause attachment of Ser/Pro-rich segments to the NH2 terminus of MLL, lacking the zinc-finger region, and that translocations occur in early hematopoietic cells, before commitment to distinct lineages.

C-MYC translocations in de novo B-cell lineage acute leukemias with t(14;18)(cell lines Karpas 231 and 353)

Rare de novo acute leukemias of mature B cells may exhibit the chromosomal translocation t(14;18)(q32.3; q21.3). We report the preliminary characterization of two cases that exhibited not only t(14;18)(q32.3;q21.3) but also the novel translocation t(8;9)(q24.1;p13.3), involving the C-MYC locus with unknown sequences at 9p13.3. From these cases, two Epstein-Barr virus negative cell lines (Karpas 231 and 353) with features identical to those seen in fresh cells from the patient have been derived. Both cell lines have complex karyotypes: in addition to both t(14;18)(q32.3;q21.3) and t(8;9)(q24.1;p13.3), cell line Karpas 231 exhibited three-way translocation t(1;3;11) (q42.3;q27.1;q23.1), whereas Karpas 353 exhibited t(1;3;7)(p32.1;q21.1;q22.1). Both cases retained immunophenotypes characteristic of mature B cells with no evidence for commitment to other hematopoietic lineages. Both cases expressed abundant, normal-sized C-MYC transcript, but no rearrangement of C-MYC DNA sequences could be detected using probes that span 80 kb around the C-MYC coding sequences. Breakpoints within the BCL-2 gene were divergent. In Karpas 353 the BCL-2 breakpoint occurred within the 3' untranslated major breakpoint region (mbr) of the gene, whereas, in Karpas 231, breaks in both the 3' mbr and in the region 5' of the gene were detected. The cytogenetic combination of t(14;18)(q32.3;q21.3) and t(8;9)(q24.1;p13.3) has been previously reported in diffuse B cell lymphomas. This combination may be a new recurrent abnormality, of central pathogenic importance in the transformation of B cells to high grade malignancies through simultaneous deregulation of BCL-2 and C-MYC genes, constitutive expression of C-MYC being driven by currently unknown DNA sequences on chromosome 9p13.3. The presence of other complex translocations including those affecting 11q23.1 may further accelerate the process of acute transformation.

A new human T-cell lymphoma cell line (Karpas 384) of the T-cell receptor gamma/delta lineage with translocation t(7:14) (p13;q11.2)

A new human T-cell non-Hodgkin lymphoma cell line of the T-cell receptor (TCR) gamma/delta lineage has been derived from the peripheral blood of a patient with a subcutaneous T-cell lymphoma in leukemic phase. The cell line (Karpas 384) initially had the same characteristics as malignant cells from the patient. Both the original tumor and the cell line failed to express any T-cell differentiation antigens other than very weak cell-surface expression of CD3 and cytoplasmic CD7; with continued growth in vitro, surface CD3 became undetectable in the presence of maintained strong cytoplasmic expression. The cell line has a complex karyotype with six abnormal chromosomes exhibiting not only t(7;14) (p13;q11.2) but also inv7(p13;q22.1), t(1;2)(q11;q35), t(2;1;14) (q35;q11-q32.1;q22.1), interstitial deletion 12(q24.1q24.3), and an unidentified marker chromosome. DNA blot analysis showed that TCR C beta and TCR J alpha-C alpha DNA sequences were in germline configuration in all restriction endonuclease digests. TCR gamma sequences showed biallelic V gamma 9-J gamma P-C gamma 1 rearrangements, the TCR gamma rearrangement detected in the majority of normal TCR gamma/delta bearing cells. Use of a range of TCR delta probes showed biallelic deletion of both J delta 1 and J delta 2, but three rearranged fragments when probed with a 3' C delta genomic probe. Similar breakpoints at 7p13 have been reported in a wide range of hematologic malignancies. Molecular cloning of the t(7;14)(p13;q11.2) translocation breakpoint in this cell line may define new DNA sequences of oncogenic potential at the 7p13 locus.

The peanut-agglutinin (PNA)-binding surface components of malignant plasma cells

Plasma cells within bone marrow aspirates from multiple myeloma patients have been shown to be reactive with the lectin peanut agglutinin (PNA). This has been recently exploited by using PNA for purging bone marrow of malignant cells in autotransplantation therapy of the disease. The purpose of this investigation was to isolate and characterize the PNA-binding proteins of myeloma cells. We used the malignant plasma cell-derived line Karpas-620 (K620) as a model, and showed by affinity chromatography, SDS-PAGE, and immunoprecipitation that, among several PNA-binding proteins, a major one is an incompletely sialylated form of CD44. CD44 is a well-known homing receptor protein which is rich in carbohydrate and usually completely sialylated so that it does not react with PNA. We have then examined the PNA reactivity of myeloma cells from different patients and showed a clear difference in the profile of PNA-binding proteins from case to case. Moreover, in contrast to K620 cells, some of the patient plasma cells tested did not have a PNA-binding form of CD44. In conclusion, therefore, we have shown that a number of different proteins participate in PNA binding by malignant plasma cells. Moreover, we have demonstrated a novel, incompletely sialylated form of CD44 on a myeloma cell line. It is known that the level of glycosylation of CD44 and other proteins may affect their function, but how this relates to the malignant behaviour of plasma cells remains to be determined.

Prevalence of human immunodeficiency virus (HIV) antibody among apparently healthy pregnant women in Nigeria

OBJECTIVE

To determine the prevalence of human immunodeficiency virus (HIV) in pregnancy in our community.

METHOD

A prospective study on 250 pregnant women currently attending the antenatal clinic at the Lagos University Teaching Hospital was carried out in 1991.

RESULT

Results obtained showed that of the 250 pregnant women screened only two (0.8%) were seropositive for HIV. This indicates the risk of vertical or materno-fetal HIV transmission in our community and underscores the need for urgency for prospective monitoring of infants born to HIV seropositive women.

CONCLUSION

Although the prevalence rate of HIV seropositivity amongst the otherwise healthy Nigerian pregnant women is only 0.8%, we advocate universal screening of HIV during pregnancy.

A comparison of human immunodeficiency virus (HIV) seropositivity and hepatitis B surface antigenemia (HBs Ag) among the same group of apparently healthy pregnant women in Lagos, Nigeria: a preliminary report

Two hundred and fifty apparently healthy pregnant women attending the Obstetrics and Gynecology Clinic of the Lagos University Teaching Hospital (LUTH), Lagos, Nigeria were screened for a comparison of the prevalence of HIV seropositivity and hepatitis B surface antigenemia (HBs Ag) amongst them. The Karpas AIDS cell test for HIV seropositivity and Bioman Hepatitis test kits were used as described by the manufacturers. HIV seropositive cases were confirmed using the Western blot test. Results revealed that out of the 250 pregnant women screened, 2 (0.8%) and 11 (4.4%) were HIV-1 and HBs Ag seropositive, respectively. However, the same 2 pregnant women now constituting 2 (18.2%) of the 11 HBs Ag positive pregnant women were simultaneously HIV-1 seropositive. Antibody to HIV-2 was not recorded in all HIV seropositive cases. This is the first report on the simultaneous prevalence of HBs Ag and HIV seropositivity among apparently healthy pregnant women in Lagos, Nigeria.

Isolation of a novel cytotoxic lymphokine (factor 2) from a human B-cell line (Karpas 160b) by preparative isoelectric focusing in the rotofor cell and chromatofocusing

Preparative isoelectric focusing (IEF) using a Rotofor cell was used for the isolation of a biologically active form of a novel cytotoxic lymphokine (Factor 2, F2) produced by a human B-cell line (Karpas 160b). We found that F2 either purified by DE52 or extracted from 160b cells using CHAPS, after adding octyl glucoside to 0.05%, could be electrofocused in the Rotofor cell without the addition of carrier ampholytes. Better recovery and separation were also achieved in the presence of 0.5% CHAPS, 3M urea. We compared the fractionation of F2 by chromatofocusing and IEF in Rotofor. Our results also showed that F2 was separable from tumor necrosis factor and phorbol myristate acetate-associated cytotoxicity by one step IEF in Rotofor. F2 purified by DE52, S-300 and Mono Q was further purified by IEF in Rotofor.

Multiparameter flow cytometric analysis of a novel cytotoxin (factor 2) induced tumor cell membrane permeability

An improved twin-probe multiparameter flow cytometric technique was applied to examine a novel cytotoxin, Factor (F2), induced tumor cell permeability. Ability to retain preloaded intracellular bis-carboxyethyl carboxyfluorescein (BCECF, green fluorescence) and to exclude extracellular propidium (red fluorescence) was measured simultaneously with forward and right-angle scatter. In addition to the two expected cell populations which were stained green negative, red positive ("membrane-damaged" and "non-viable", Region 2), and green positive, red negative ("membrane intact" and "viable", Region 3), a third population was seen which fluoresced neither green nor red and displayed intermediate light scatter characteristics (Region 1). K562 cells progressed from Region 3 to Region 1, and then from Region 1 to Region 2 after treatment with F2. These results suggest that sequential changes in membrane structure lead to increased permeability, first with respect to intracellular BCECF and then in turn to extracellular propidium. Flow cytometric changes caused by F2 were detectable 10 min after treatment with 2.5 U/ml of F2, and 5 min after 10 or 40 U/ml of F2. Flow cytometric analysis showed that F2-induced tumor cell lysis and growth inhibition were accompanied by rapid alternations in tumor cell membrane permeability. Flow cytometric analysis also distinguished F2 cytotoxicity from phorbol myristate acetate (PMA) associated cytotoxicity to K562 cells and determined that F2 produced spontaneously or induced by PMA and/or ciprofloxacin had a similar ability to induce tumor cell membrane permeability change.

Immunochemical localization of a region of chaperonin-60 important for productive interaction with chaperonin-10

An IgG1 monoclonal antibody (mAb 54G8) which binds to both Bordetella pertussis chaperonin-60 (cpn60) and Escherichia coli cpn60 (GroEL) was produced. mAb 54G8 as well as Fab fragments prepared from this antibody were found to abolish the ability of chaperonin-10 (cpn10, GroES) to inhibit the ATPase activity of both B. pertussis cpn60 and E. coli cpn60. Electron microscopy was used to localize the binding site of the monoclonal antibody on the B. pertussis cpn60 molecule. In the absence of the antibody, the B. pertussis molecule exhibited the tetradecameric structure typical of cpn60. Both end views (showing 7-fold symmetry of the face of the molecule) and side views were evident. When mAb 54G8 was bound, B. pertussis cpn60 molecules appeared to be cross-linked so that they formed long chains. Only side views of the molecules were seen in these long chains. When B. pertussis cpn60 complexed with Fab fragments of mAb 54G8 was examined, chains were no longer observed. Instead, side views of B. pertussis cpn60 were often seen with Fab fragments extending from the ends of the molecule. These data indicate that mAb 54G8 appears to bind at or near the end of the B. pertussis cpn60 molecule and that binding of mAb 54G8 at this location affects the ability of cpn10 to productively interact with cpn60, most likely either by sterically blocking the binding of cpn10, by affecting the conformation of cpn60 in such a way that it no longer binds cpn10, or by inhibiting proper transduction of the effects of cpn10 binding.

Phosphate derivatives of AZT display enhanced selectivity of action against HIV 1 by comparison to the parent nucleoside

Novel phosphate derivatives of the anti-HIV nucleoside analogue AZT have been prepared by phosphorochloridate chemistry. In particular, phosphates carrying ester-containing side-chains are described. These materials are designed to act as membrane-soluble pro-drugs of the bio-active free nucleotides. In vitro evaluation revealed the compounds to have a pronounced, selective antiviral activity. In several cases the phosphate derivatives are more selective in their action than the parent nucleoside AZT. In particular, this arises from the low toxicity of the phosphate pro-drugs by comparison to AZT. These data support the suggestion that the phosphate derivatives exert their biological effects via intracellular release of the nucleotide forms, and suggests that such pro-drug forms may be worthy of further study.

Inhibition of human immunodeficiency virus and growth of infected T cells by the immunosuppressive drugs cyclosporin A and FK 506

The effects of the immunosuppressive drugs cyclosporin A and FK 506 were studied on cells chronically infected with human immunodeficiency virus type 1 (HIV-1) as well as on uninfected and newly infected cells. When cells chronically infected with HIV-1 or with HIV-2 were cocultivated with uninfected cells in the presence of cyclosporin A or FK 506 there was a delay in the formation of syncytia and of cytopathic effects. This inhibitory effect was not due to decreased membrane expression of CD4. In addition, there was an approximately 100-fold reduction in the yield of infectious HIV-1 when the infected cells were grown in the presence of these drugs, a finding consistent with other evidence of decreased HIV expression. Both drugs were found to inhibit the growth of chronically infected cells at concentrations that did not inhibit the growth of the uninfected cells. These results, demonstrating that cyclosporin A and FK 506 interfere with HIV production and selectively inhibit the growth of infected cells, suggest that they may be useful in the treatment of this infection and indicate further cellular targets for antiviral agents.

Evolution of the primate lentiviruses: evidence from vpx and vpr

The genomes of the four primate lentiviral groups are complex and contain several regulatory or accessory genes. Two of these genes, vpr and vpx, are found in various combinations within the four groups and encode proteins whose functions have yet to be elucidated. Comparison of the encoded protein sequences suggests that the vpx gene within the HIV-2 group arose by the duplication of an ancestral vpr gene within this group. Evolutionary distance analysis showed that both genes were well conserved when compared with viral regulatory genes, and indicated that the duplication occurred at approximately the same time as the HIV-2 group and the other primate lentivirus groups diverged from a common ancestor. Furthermore, although the SIVagm vpx proteins are homologous to the HIV-2 group vpx proteins, there are insufficient grounds from sequence analysis for classifying them as vpx proteins. Because of their similarity to the vpr proteins of other groups, we suggest reclassifying the SIVagm vpx gene as a vpr gene. This creates a simpler and more uniform picture of the genomic organization of the primate lentiviruses and allows the genomic organization of their common precursor to be defined; it probably contained five accessory genes: tat, rev, vif, nef and vpr.

Production and induction of a novel cytotoxin (factor 2) by a human B-cell line

The human B-cell line, Karpas 160, was found to produce Factor 1 and 2 (F1 and F2). F1 was found to be indistinguishable from tumor necrosis factor beta (TNF-beta), while F2 appears to be a new cytotoxin. We used several stimuli alone or in combination to trigger the 160b cells, a subclone of Karpas 160, to produce higher yield of F2. The optimal culture times, concentrations of cells and a range of stimuli were studied. We found that 20-25 ng/ml of phorbol myristate acetate (PMA) effectively induced the higher production of F2. Pretreatment of the cells with sodium butyrate enhanced F2 production. Production of TNF but not F2 was inhibited when the cells were cultured with tunicamycin and PDB. When ciprofloxacin or cycloheximide was added to the medium, F2 production in the presence of PMA was amplified. When 160b cells were cocultured with K562 cells, low levels of F2 induction were observed. We found that most types of human tumor cell lines were highly susceptible to F2, but less sensitive or even resistant to TNF. In contrast, normal human cell lines were not susceptible to F2. Therefore, it appears that F2 could be a new human cytotoxin.

Relationship between a novel human cytotoxin (factor 2) produced by a B cell line (Karpas 160) and phorbol-myristate-acetate-associated cytotoxicity

We found that 160b cells, a subclone of Karpas 160 human B cell line, spontaneously secreted a novel cytotoxin, factor 2 (F2). F2 was also extracted from the cells by 60% ammonium sulphate, 0.5% CHAPS and 0.28% Triton X-114. We were able to show that phorbol myristate acetate (PMA) greatly enhanced the production of F2, and PMA may also account for part of the putative F2 cytotoxic activity to K562 cells in crude preparations. We compared the cytotoxic effect of F2 with PMA-associated F2-like cytotoxicity to K562 cells as well as the adequacy of our schemes to purified F2 with regard to its separation from PMA. We found that it was possible to separate PMA from F2 preparations by gel filtration and Rotofor preparative isoelectric focusing. The fate of PMA was also monitored with 3H-PMA and chromatographic profiles of 3H-PMA were studied using DE52 and gel filtration chromatography. We were able to establish that less than 2.9% of the cytotoxicity to K562 was due to PMA. We also found that the radioactive peaks and cytotoxicity peaks to K562 were not well correlated, indicating that the cytotoxicity was not mainly due to remaining PMA. Activated charcoal removed virtually all F2 and PMA but not tumour necrosis factor activity. Our results also showed that cytotoxicity to K562 resulting from F2 or PMA-associated proteins had different physicochemical properties, indicating that they are different molecular entities. These findings are consistent with the earlier observation that 160 cells produce F2 spontaneously and that PMA can amplify its production significantly.

Characterization and partial purification of a novel cytotoxic lymphokine (factor 2) produced by a human B cell line (Karpas 160)

A subclone (160b) of the human B cell (Karpas 160) was shown to produce a novel cytotoxic lymphokine [Factor 2 (F2)] in addition to tumour necrosis factor alpha (TNF-alpha) and beta (TNF-beta). F2 was found to have selective toxicity to numerous human tumour cell lines, particularly the erythroleukaemic cell line K562, whereas TNF-alpha/beta were not cytotoxic to these cells, even at relatively high concentrations. Our studies have shown that F2 activity in crude preparations is heterogeneous both in its molecular weight, isoelectric point (pI) and hydrophobicity, which depends not only on the source of F2 cytotoxicity but also on the conditions of methods for its production. Our studies also showed that F2 was separable from TNF by DE52, S-300 gel filtration and Rotofor isoelectric focusing. F2 was partially purified up to 1000-fold by two procedures. The major active form, as assessed by gel filtration was of mol. wt of 45-67 kDa. On SDS-PAGE, F2 activity was recovered mainly from two regions of the gels corresponding to 10-14 kDa and 60-70 kDa. Antibodies of human TNF-alpha, TNF-beta, IFN-alpha, IFN-gamma, and TGF-beta failed to prevent F2-mediated cytotoxicity to K562. F2 activity was not inhibited by mannose-6-PO4 or mouse mAb to rat granule content, both of which have been reported to block human natural killer cytotoxic factor. Our studies indicated that F2 is likely to be a distinct human cytokine with selective cytotoxic activity against tumour cells.

Oligonucleotide primers for polymerase chain reaction amplification of human immunoglobulin variable genes and design of family-specific oligonucleotide probes

In recent work, the polymerase chain reaction (PCR) has been used to amplify rearranged mouse and human immunoglobulin heavy and kappa light chain variable (V) genes. Here we have optimized the design of the PCR primers for human V genes and used them to amplify cDNA from human peripheral blood lymphocytes. Cloning and sequencing revealed a diverse repertoire of V genes, and the presence of members of each human V gene family. After alignment of the sequences, we identified a region conserved within V gene families, but differing between families, and used this to design family-specific oligonucleotide probes.

Nucleotide sequence of a Guinea-Bissau-derived human immunodeficiency virus type 2 proviral clone (HIV-2CAM2)

We report the complete nucleotide sequence of a human immunodeficiency virus type 2 (HIV-2) isolate from Guinea-Bissau (HIV-2CAM2). The genomic organization of HIV-2CAM2 is identical to that of other HIV-2 isolates but contains a stop codon in the pol gene. The deduced amino acid sequences of the viral proteins show variation of 20% in the gag, pol and vpx regions, and 25 to 45% in the tat, env and nef regions when compared to other isolates of HIV-2. This is greater than the variation observed between isolates of HIV-1.

Polymerase chain reaction evidence for human immunodeficiency virus 1 neutralization by passive immunization in patients with AIDS and AIDS-related complex

We tried to assess the long-term safety and potential efficacy of passive immunization in AIDS-related-complex (ARC) and AIDS patients. We also wanted to establish whether hyperimmune plasma from healthy human immunodeficiency virus 1 (HIV-1)-infected individuals clears the cell-free virus from circulation. Using the polymerase chain reaction (PCR), we were able to provide conclusive evidence that hyperimmune plasma is effective and maintains long-term neutralization of viremia. Using the cell test, we found that in most patients the total antibody level was maintained; in one of the ARC patients, it actually increased 8-fold and has remained at that level for nearly 2 years. The CD4+ cell count decreased in the AIDS patients but was stable in the ARC patient. Clinically, there was an initial improvement in all patients, but five of six of the advanced/terminal AIDS patients had died by month 17. Our studies suggest that passive immunization may be safe in ARC and AIDS patients. It reduces HIV-1 viremia to levels undetectable even by PCR. To advanced/terminal patients, the benefit is of limited duration, while to ARC patients it may be long-term. Therefore, passive immunization should start early in the disease.

A new human B-cell non-Hodgkin's lymphoma cell line (Karpas 422) exhibiting both t (14;18) and t(4;11) chromosomal translocations

A unique B-cell non-Hodgkin's lymphoma (NHL) cell line (Karpas 422), bearing both t(14;18) and t(4;11) chromosomal translocations as well as several other chromosomal abnormalities, has been established from the pleural effusion of a patient with chemotherapy-resistant NHL. This cell line has the same karyotypic features as malignant cells from the patient. The major cell clone is characterized chromosomally by 46,XX t(2;10)(p23;q22.1), t(4;11)(q21.3; q23.1), t(14;18)(q32.1;q21.3), t(4;16)(q21.3;p13.1). Both phenotypically and genotypically, the cell line has features of a mature B-cell neoplasm with no evidence for commitment to other lineages. Rearrangements of the C-ETS-1 oncogene and N-CAM-1 and CD3 genes that map to 11q23 were not detected by conventional Southern analysis. BCL-2 was rearranged within the major breakpoint cluster. The K422 cell line has a unique karyotype; this is the first occasion that the t(4;11) translocation has been described in a t(14;18) lymphoma. The cell line will be of value in determining the molecular nature of the t(4;11) translocation.

A new human plasma cell line, Karpas 620, with translocations involving chromosomes 1, 11 and 14

We report here the establishment of a new cell line, Karpas 620 (K620), from the peripheral blood of an elderly woman with an IgG-kappa plasma cell leukaemia (PCL). The line has the same hypotetraploid karyotype as the fresh cells from the patient. The cultured cells have the ultrastructural appearance of plasma cells with abundant rough endoplasmic reticulum (RER) and secrete kappa light chain. They are positive for surface antigens HLA DR, and WR17 (CD 37) and negative for CD1, CD3, CD4 and CD8. Using high resolution (HR) cytogenetic analysis it has been possible to identify all the marker chromosomes including several rearrangements commonly seen in malignancies of B cell lineage. These are a 14q+ marker with a typical 'Burkitt' morphology der(14)(pter----q32.3::8q24.1----qter) but with no reciprocal 8q-, and three translocations involving chromosome 11 at q13 with partners other than chromosome 14, namely 1q32.1, 8q24.22 and 13q14.3. An earlier report of molecular studies on the DNA of K620 has shown a rearrangement near the region on 11q13 designated BCL-1 (Rabbitts et al. 1988). This is the first report of a rearrangement in the region of 11q13 in a cell line originating from a case of plasma cell leukaemia.