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Query: UMLS:C0079731 (B-cell lymphoma)
 16,671 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The B cell lymphoma I.29 consists of a mixture of cells expressing membrane-bound immunoglobulin M (IgM) (lambda) and IgA (lambda) of identical idiotypes. Whereas most of the cells express either IgM or IgA alone, 1 to 5% of the cells in this tumor express IgM and IgA simultaneously within the cytoplasm and on the cell membrane (R. Sitia et al., J. Immunol. 127:1388-1394, 1981; R. Sitia, unpublished data). When IgM+ cells are purified from the lymphoma and passaged in mice or cultured, a portion of the cells convert to IgA+. These properties suggest that some cells of the I.29 lymphoma may undergo immunoglobulin heavy chain switching, although it is also possible that the mixed population was derived by a prior switching event in a clone of cells. We performed Southern blotting experiments on genomic DNAs isolated from populations of I.29 cells containing variable proportions of IgM+ and IgA+ cells and on a number of cell lines derived from the lymphoma. The results were consistent with the deletion model for heavy chain switching, as the IgM+ cells contained rearranged mu genes and alpha genes in the germ line configuration on both the expressed and nonexpressed heavy chain chromosomes, whereas the IgA+ cells had deleted both mu genes and contained one rearranged and one germ line alpha gene. In addition, segments of DNA located within the intervening sequence 5' to the mu gene, near the site of switch recombination, were deleted from both the expressed and the nonexpressed chromosomes. Although mu genes were deleted from both chromosomes in the IgA+ cells, the sites of DNA recombination differed on the two chromosomes. On the expressed chromosome, Smu sequences were recombined with S alpha sequences, whereas on the nonexpressed chromosome, Smu sequences were recombined with S gamma 3 sequences.
Mol Cell Biol 1982 Aug
PMID:Rearrangements and deletions of immunoglobulin heavy chain genes in the double-producing B cell lymphoma I.29. 629 Aug 69

Using a simple scraping technique to obtain DNA directly from archival hematoxylin and eosin-stained slides, we successfully amplified clonal immunoglobulin heavy chain gene rearrangements (IGR) from lymphomatous infiltrates, as small as 1 mm2. The fragments amplified by the polymerase chain reaction (PCR) were identical in size to those from corresponding whole unstained sections freshly cut from the paraffin-embedded blocks. Using this technique, we detected clonal IGR from the scraping of a small lymphomatous nodule in the colon, although no amplified fragments were detected from the whole section. Furthermore, we demonstrated that two morphologically different areas in a case of B-cell lymphoma have identical amplified fragments. It is important that no amplified fragments were detected in scrapings from adjacent nonneoplastic areas. Although DNA recovered from scrapings was partially degraded, fragments as large as 725 base pairs were successfully amplified from a slide stored more than 11 years. This technique thus allows detection of clonal IGR in tissues focally involved by B-cell lymphoma and molecular genetic studies of focal pathologic lesions as an alternative to in situ hybridization or in situ PCR. Finally, this technique can be applied to archival slides when tissue blocks are not available.
Diagn Mol Pathol 1993 Sep
PMID:Detection of clonal immunoglobulin heavy chain gene rearrangements by polymerase chain reaction in scrapings from archival hematoxylin and eosin-stained histologic sections: implications for molecular genetic studies of focal pathologic lesions. 750 82

We have identified a murine B-cell lymphoma cell line, CH1, that has a much-diminished capacity to express increased levels of heat shock proteins in response to heat stress in vitro. In particular, these cells cannot synthesize the inducible 72-kDa heat shock protein (HSP72) which is normally expressed at high levels in stressed cells. We show here that CH1 fails to transcribe HSP72 mRNA after heat shock, even though the heat shock transcription factor, HSF, is activated correctly. After heat shock, HSF from CH1 is found in the nucleus and is phosphorylated, trimerized, and capable of binding the heat shock element. We propose that additional signals which CH1 cells are unable to transduce are normally required to activate hsp72 transcription in vitro. Surprisingly, we have found that when the CH1 cells are heated in situ in a mouse, they show normal expression of HSP72 mRNA and protein. Therefore, CH1 cells have a functional hsp72 gene which can be transcribed and translated when the cells are in an appropriate environment. A diffusible factor present in ascites fluid is capable of restoring normal HSP72 induction in CH1 cells. We conclude that as-yet-undefined factors are required for regulation of the hsp72 gene or, alternatively, that heat shock in vivo causes activation of hsp70 through a novel pathway which the defect in CH1 has exposed and which is distinct from that operating in vitro. This unique system offers an opportunity to study a physiologically relevant pathway of heat shock induction and to biochemically define effectors involved in the mammalian stress response.
Mol Cell Biol 1995 Feb
PMID:In vivo growth of a murine lymphoma cell line alters regulation of expression of HSP72. 782 22

The low affinity receptor for IgE (Fc epsilon RII or CD23), expressed primarily on mouse B cells, is known to be upregulated by interleukin-4 (IL-4) at both the mRNA and protein levels. Fc epsilon RII expression is superinduced when the IL-4 is combined with cell activation. In order to explore the molecular regulation of Fc epsilon RII expression, mouse B cell lines were screened to develop a cell line model. The B cell lymphoma A20.1, was found to behave in a manner similar to mouse B cells in that Fc epsilon RII levels are very low on cells cultured in media alone (< 10(3)/cell), increased by culture in the presence of IL-4, and superinduced by LPS and IL-4 (> 10(5)/cell). The steady state mRNA levels for Fc epsilon RII corresponded to the level of cell surface expression. Transcription assays indicated that the Fc epsilon RII level increases could be explained entirely by increased transcription rates. The A20.1 cell line was subsequently used to analyse the Fc epsilon RII promoter. Nested deletion analysis of the 1.3 kB 5' of the mouse Fc epsilon RII transcription start site, using CAT reporter plasmids transfected into A20.1 cells, identified major elements activating the Fc epsilon RII promoter within 250 bp of the transcription start site. Constructs containing greater than 250 bp of 5' sequence showed significantly reduced CAT activity suggesting negative regulatory regions. Coincident with the restricted tissue expression of murine Fc epsilon RII, the promoter was B cell specific in that little CAT expression was seen in fibroblast, mast cells or T cell lines. Expression was seen, however, in both mouse and human B cell lines. Finally, the promoter was analysed for response to IL-4. Stimulation with IL-4 plus LPS resulted in only a modest increase in CAT activity (approximately 2-fold), in contrast to transcription assays, where increases approximated that seen at the cell surface. Thus, the IL-4 response must also require sequences distal to the regions examined.
Mol Immunol 1994 Oct
PMID:Molecular mechanisms of murine Fc epsilon RII/CD23 regulation. 793 5

Epstein-Barr virus (EBV) has been detected in African Burkitt's lymphoma, posttransplant lymphoproliferative disease, and a variable fraction of Hodgkin's lymphomas. To assess if EBV is associated with other lymphoid proliferations, we evaluated a wide variety of benign and malignant lymphoid lesions, using polymerase chain reaction and a sensitive in situ hybridization method. Abundant EBV+ cells were seen in posttransplant lymphomas, some B cell immunoblastic lymphomas, and in tonsils from patients with infectious mononucleosis. Intermediate numbers of EBV+ cells were seen in a mixed B cell lymphoma, peripheral T cell lymphomas, and in syncytial variants of Hodgkin's disease as well as a lymph node from a patient with infectious mononucleosis. Low numbers of EBV+ cells were detected in normal and reactive lymph nodes, B and T cell lymphomas, and Hodgkin's lymphomas. The variable extent of EBV infection in lymphoid lesions suggests that EBV may play a variety of roles in the development of malignant and nonmalignant lymphoid lesions.
Diagn Mol Pathol 1994 Mar
PMID:Presence of Epstein-Barr virus in many types of benign and malignant lymphoid lesions. Detection by polymerase chain reaction and in situ hybridization. 816 52

Formalin-fixed, paraffin-embedded tissue from B-cell malignant lymphomas (26), reactive lymphadenopathies (8), non-B-cell malignancies (5), and atypical lymphoproliferative lesions (7) were analyzed for clonal immunoglobulin heavy chain gene rearrangement by the polymerase chain reaction (PCR), using consensus primers for the variable and joining regions of the gene. By employing a high-resolution gel electrophoresis technique, we were able to demonstrate one or two dominant bands, indicating a clonal population, in 15 of the 23 cases (65%) of B-cell lymphoma in which amplification occurred. Six of six reactive lymph nodes in which amplification occurred produced a multi-banded pattern indicative of a polyclonal population. This improved PCR technique allows a clearer distinction between clonal and polyclonal patterns than other previously proposed methods. It also works well in paraffin-embedded tissue and may therefore be a useful adjunct to the diagnostic armamentarium applied to archival material.
Diagn Mol Pathol 1993 Mar
PMID:Determination of B-cell clonality in paraffin-embedded lymph nodes using the polymerase chain reaction. 828 25

Interleukin-5 (IL-5) and IL-6 have both been reported to act as B-cell differentiation factors by stimulating activated B cells to secrete antibody. However, it has not been possible to directly compare the effects of these two lymphokines because of the lack of a suitable B-cell line capable of responding to both. We have identified a clonal, inducible B-cell lymphoma, CH12, that has this property. Both IL-5 and IL-6 can independently stimulate increases in steady-state levels of immunoglobulin and J-chain mRNA and proteins, and they both induce the differentiation of CH12 into high-rate antibody-secreting cells. Nevertheless, there are significant differences in the activities of these two lymphokines. First, while IL-6 acts only as a differentiation factor, IL-5 also augments the proliferation of CH12 cells. Second, the differentiation stimulated by IL-5 but not by IL-6 is partially inhibited by IL-4. Inhibition of IL-5-induced differentiation was not at the level of IL-5 receptor expression, since IL-4 did not inhibit IL-5-induced proliferation. Third, IL-5 but not IL-6 stimulated increased mouse mammary tumor proviral gene expression in CH12 cells. These results demonstrate that while both IL-5 and IL-6 may act as differentiation factors for B cells, they induce differentiation by using at least partially distinct molecular pathways. Our results also establish that B cells characteristic of a single stage of development can independently respond to IL-4, IL-5, and IL-6.
Mol Cell Biol 1993 Jul
PMID:Interleukin-5 (IL-5) and IL-6 define two molecularly distinct pathways of B-cell differentiation. 832 Dec

The major histocompatibility (MHC) class I antigens are coordinately expressed in most cells. However, some tumors or virus-infected cells lack expression of one MHC class I antigen, while expression of the other MHC class I antigens is unaffected. We previously described the selective expression of MHC class I antigens on a B-cell lymphoma from SJL/J mice called RCS5. This tumor expresses H-2Ks, but has lost cell surface expression of H-2Ds. To understand the mechanism responsible for the selective loss of H-2Ds on the cell surface, we analysed H-2Ds mRNA and protein in the RCS5 tumor. Here we report that H-2Ds mRNA was expressed in RCS5, but H-2Ds protein was not detected in cell lysates. To determine whether the H-2Ds mRNA from RCS5 was able to direct the synthesis of H-2Ds protein, we performed cDNA cloning, in vitro translation and gene transfer experiments using a cell line related to RCS5 (cRCS-X). Our results indicated that the inhibition of H-2Ds expression in cRCS-X occurred after transcription of a non-defective H-2Ds mRNA. Furthermore, H-2Ds antigen expression was restored in cRCS-X using a retroviral vector to express the recombinant H-2Ds cDNA. These results indicate that the inhibition of H-2Ds expression could be overcome either by out competing an inhibitor that functions in trans or by removing cis-acting regulatory sequences from the endogenous H-2Ds mRNA.
Mol Immunol 1995 Oct
PMID:Selective loss of H-2Ds antigen on a murine B lymphoma due to a post-transcriptional block in expression. 854 50

The murine monoclonal antibody, LL2, is a B-cell (CD22)-specific IgG2a which has been demonstrated to be clinically significant in the radioimmunodetection of non-Hodgkin's B-cell lymphoma. The antibody carries a variable region-appended glycosylation site in the light chain and is rapidly internalized upon binding to Raji target cells. Humanization of LL2 was carried out in order to develop LL2 as a diagnostic and immunotherapeutic suitable for repeated administration. Based on the extent of sequence homology, and with the aid of computer modeling, we selected the EU framework regions (FR) 1, 2 and 3, and the NEWM FR4 as the scaffold for grafting the heavy chain complementarity determining regions (CDRs), and REI FRs for that of light chains. The light chain glycosylation site, however, was not included. Construction of the CDR-grafted variable regions was accomplished by a rapid and simplified method that involved long DNA oligonucleotide synthesis and the polymerase chain reaction (PCR). The humanized LL2 (hLL2), lacking light chain variable region glycosylation, exhibited immunoreactivities that were comparable to that of chimeric LL2 (cLL2), which was shown previously to have antigen-binding properties similar to its murine counterpart, suggesting that the VK-appended oligosaccharides found in mLL2 are not necessary for antigen binding. Moreover, the hLL2 retained its ability to be internalized into Raji cells at a rate similar to its murine and chimeric counterparts.
Mol Immunol 1995 Dec
PMID:Construction and characterization of a humanized, internalizing, B-cell (CD22)-specific, leukemia/lymphoma antibody, LL2. 864 11

Cross-linking surface immunoglobulin (Ig)M on the WEHI-231 B-cell lymphoma results in decreased cell size, G1/S growth arrest, and finally DNA cleavage into oligonucleosomal fragments that are the classical features of apoptotic cells. Treatment of WEHI-231 cells with anti-IgM in early G1 phase prevents phosphorylation of the retinoblastoma gene product (pRb) and inhibits entry into S phase. Using unsynchronized cells, we previously demonstrated that cyclin A-associated and Cdk2-dependent GST-pRb kinase activity were inhibited in WEHI-231 cells treated with anti-IgM. We now show that progression of elutriated early G1 phase WEHI-231 cells from early into late G1 phase is accompanied by an increase in the abundance of cyclin A protein and cyclin A-associated kinase activity. Treatment of early G1 cells with anti-IgM prevented this increase in cyclin A-associated kinase activity at late G1, despite minimal changes in the overall level of cyclin A and Cdk2 proteins. Late G1 cells, which already possess high cyclin A-associated kinase activity, were insensitive to anti-IgM treatment and were able to complete the cell cycle. We also found that anti-IgM-treated cells contained increased amounts of the Cdk inhibitor protein p27Kip1. Essentially all of the cyclin A in treated cells was associated with p27, a result which we propose explains the lack of cyclin A/Cdk2 kinase activity. Accumulation of p27 in cyclin A kinase complexes, however, did not decrease the amount of Cdk2 bound to cyclin A. Thus, cross-linking IgM on growth-inhibitable B-cell lymphomas affects cyclin A kinase activity by increasing the levels of p27 in this complex, thus preventing productive pRb phosphorylation and leading to cell cycle arrest and subsequent apoptosis. These results are discussed in terms of the cell cycle restriction points that regulate lymphocyte function, as well as the lineage-specific differences in cell cycle control.
Mol Biol Cell 1996 Apr
PMID:Role of cyclin A and p27 in anti-IgM induced G1 growth arrest of murine B-cell lymphomas. 873 99


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