Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0079731 (B-cell lymphoma)
 16,671 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 78-year-old woman complaining of a neck mass underwent right hemithyroidectomy. The 7 x 6 cm thyroid tumor consisted predominantly of mildly atypical, epithelial membrane antigen-positive plasma cells and scattered lymphoid follicles. Features of follicular colonization (plasma cell infiltration into germinal centers) were noted. Numerous CD45RO-positive reactive T cells and a smaller number of CD20-positive blast-like B cells were also distributed among the plasma cell infiltrate. IgG, kappa-type monoclonality with J-chain reactivity was identified in the plasma cells, including those in the lymphoid follicles. The association of pre-existing lymphocytic thyroiditis was confirmed histologically in the non-tumorous thyroid tissue. The tumor exhibited deposition of reticulin fiber-rich, amorphous eosinophilic substances, provoking pronounced foreign body reactions. The deposit, polytypically immunoreactive for immunoglobulin gamma-, mu-, kappa- and lambda-chains, beta 2-microglobulin and HLA-DR, was scarcely reactive upon amyloid staining, and consisted ultrastructurally of electron-dense, non-fibrillar material and entrapped collagen fibers. Multiple myeloma was ruled out by laboratory, histologic and clinical examinations. The possible categorization of this extramedullary plasmacytoma of the thyroid within low-grade B cell lymphoma of the mucosa-associated lymphoid tissue (MALT) is discussed.
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PMID:Extramedullary plasmacytoma of the thyroid, associated with follicular colonization and stromal deposition of polytypic immunoglobulins and major histocompatibility antigens. Possible categorization in MALT lymphoma. 147 63

Raji-HN2 is a B cell lymphoma (Burkitt lymphoma) line that was made resistant to nitrogen mustard. The drug-resistant phenotype was accompanied by changes in gene expression. The expression of four unrelated genes was examined by Northern blot analysis. Raji-HN2 cells were found to contain about twice the number of actin mRNA found in Raji cells. Both cell lines were found to contain equivalent amounts of beta 2-microglobulin, c-myc oncogene, and immunoglobulin C mu mRNAs. The C mu mRNA was, however, larger in size in Raji-HN2 cells. Alterations in actin and C mu mRNAs in Raji-HN2 cells were not due to gene amplification or rearrangement because Southern blot analysis revealed no changes in the genomic organization of these genes. The increased actin mRNA content was correlated with an increased actin content of Raji-HN2 cells. The F-actin (stained with 7-nitrobenz-2-oxa-1,3-diazolylphallacidin) content of single cells was quantitated in a meridian interactive laser cytometer. Raji-HN2 cells contained about twice the amount of F-actin present in the parental Raji cells. Similar results were obtained when large populations, 10(6) cells each, were examined in a flow cytometer.
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PMID:Altered actin and immunoglobulin C mu expression in nitrogen mustard-resistant human Burkitt lymphoma cells. 250 99

Crosslinked IgM molecules expressed on the surface of immature B cells mediate responses that inhibit further development, in contrast to the activational and proliferative events that follow crosslinking of the mu heavy chain in mature B cells. Concomitant with this change in IgM signaling capacity is the appearance of surface IgD, which has been proposed to modulate the response elicited by the mu heavy chain. In an attempt to gain insight into the mechanism(s) by which surface IgM is able to generate such disparate responses, delta heavy chain gene transfectants of the murine B-cell lymphoma line WEHI-231 were established. WEHI-231 cells resemble phenotypically immature B cells, in addition to being highly susceptible to the growth-inhibitory effect of surface IgM cross-linking. Endogenous mu and exogenous delta heavy chains expressed on the surface of the transfectants were compared for their role in cell proliferation and on gene expression. Our results indicate that the growth-inhibitory response is associated only with the mu heavy chain and that surface IgD does not mediate such a response. Furthermore, in contrast to IgM, IgD molecules appear to have an inductive effect on the expression of Myc and the endogenous mu and exogenous delta Ig heavy chain genes but not on the expression of the housekeeping gene encoding beta 2-microglobulin. These findings suggest that IgM and IgD are functionally distinct when expressed on the surface of an immature B cell.
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PMID:Functional differences between immunoglobulins M and D expressed on the surface of an immature B-cell line. 313 79

The intracellular transport of two closely related membrane glycoproteins was studied in the murine B cell lymphoma line, AKTB-1b. Using pulse-chase radiolabeling, the kinetics of appearance of the class I histocompatibility antigens, H-2Kk and H-2Dk, at the cell surface were compared and found to be remarkably different. Newly synthesized H-2Kk is transported rapidly such that all radiolabeled molecules reach the surface within 1 h. In contrast, the H-2Dk antigen is transported slowly with a half-time of 4-5 h. The rates of surface appearance for the two antigens closely resemble the rates at which their Asn-linked oligosaccharides mature from endoglucosaminidase H (endo H)-sensitive to endo H-resistant forms, a process that occurs in the Golgi apparatus. This suggests that the rate-limiting step in the transport of H-2Dk to the cell surface occurs before the formation of endo H-resistant oligosaccharides in the Golgi apparatus. Subcellular fractionation experiments confirmed this conclusion by identifying the endoplasmic reticulum (ER) as the site where the H-2Dk antigen accumulates. The retention of this glycoprotein in the ER does not appear to be due to a lack of solubility or an inability of the H-2Dk heavy chain to associate with beta 2-microglobulin. Our data is inconsistent with a passive membrane flow mechanism for the intracellular transport of membrane glycoproteins. Rather, it suggests that one or more receptors localized to the ER membrane may mediate the selective transport of membrane glycoproteins out of the ER to the Golgi apparatus. The fact that H-2Kk and H-2Dk are highly homologous (greater than or equal to 80%) indicates that this process can be strongly influenced by limited alterations in protein structure.
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PMID:Intracellular transport of membrane glycoproteins: two closely related histocompatibility antigens differ in their rates of transit to the cell surface. 392 33

The genes that code for the human major histocompatibility class I antigens, HLA-A2 and HLA-B7, were introduced into human, monkey, and mouse cell lines by cotransfection with suitable biochemical markers and the fluorescence-activated cell sorter was used to identify and/or select stable cell populations expressing high surface levels of these antigens. Levels of expression obtained were similar to those observed for endogenous HLA antigens on various human cell lines and were 25-80% of those observed on the human B-lymphoblastoid cell line JY. Serologically defined HLA-A2 and HLA-B7 polymorphic determinants remained intact on all transfected recipient cells analyzed. Cloned human allospecific cytotoxic T lymphocytes (CTL) specific for HLA-A2 or HLA-B7 were capable of lysing appropriate HLA-transfected human cells with comparable efficiency to JY cell lysis. Two of 10 CTL clones lysed appropriate monkey cell transfectants with approximately equal to 20% the efficiency of human cell transfectants. No specific lysis of any HLA-transfected mouse cell lines, including a B cell lymphoma, was observed despite comparable levels of surface antigen expression or after induction of higher levels by mouse gamma-interferon. Furthermore, L cells expressing human beta 2-microglobulin in addition to HLA-A2 or -B7 were not lysed by these CTL. Thus, an additional species-specific component may be involved in lysis by allogeneic CTL--possibly related to the function(s) of other surface proteins on target cells.
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PMID:Recognition of HLA-A2 and -B7 antigens by cloned cytotoxic T lymphocytes after gene transfer into human and monkey, but not mouse, cells. 639 Apr 42

Programmed cell death (PCD) or apoptosis is a common form of cellular demise during embryogenesis, tumorigenesis and clonal selection in the immune system. The bcl-2 proto-oncogene has been recently implicated as a potential physiological regulator of the PCD pathway. Gene transfer studies have shown that overexpression of bcl-2 blocks apoptosis mediated by several stimuli in cultured cell lines and promotes the survival of B and T lymphocytes in transgenic mice. However, it remains unclear whether under normal conditions bcl-2 is responsible for controlling cell death. We have investigated the role of bcl-2 in the antimembrane IgM (mIgM)-induced apoptotic death of WEHI-231 B cell lymphoma, a model that mimics clonal deletion of immature B cells by antigen. Signalling of mIgM receptors triggered downregulation of both bcl-2 RNA and protein, and induced apoptosis in WEHI-231 B cells. This effect appeared to be specific since (i) the levels of beta 2-microglobulin and beta-actin RNA remain unchanged and (ii) signalling of the apoptosis-resistant B cell lymphoma line BAL-17 with anti-mu was not associated with downregulation of bcl-2 RNA. However, stable expression of bcl-2 by transfection did not rescue WEHI-231 B cells from apoptosis, yet WEHI-231 cells overexpressing bcl-2 were more resistant to programmed cell death induced by heat-shock.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Programmed cell death by bcl-2-dependent and independent mechanisms in B lymphoma cells. 846 5