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Query: UMLS:C0026764 (multiple myeloma)
 36,148 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the pathophysiology of erythropoiesis in 62 patients with multiple myeloma and examined whether it would establish a rational basis for the treatment of their anaemia with recombinant human erythropoietin. Erythropoietin (Epo) production was evaluated by serum levels and erythropoiesis was quantitated by serum transferrin receptor (TfR) levels, both assessed relative to the degree of anaemia. Instead of the expected stimulation of erythropoiesis in response to anaemia, haematocrit correlated positively with marrow erythropoietic activity, indicating that the mechanism of anaemia was primarily defective red cell production. Erythropoiesis decreased and anaemia worsened significantly with advancing clinical stage. 25% of the patients had inadequate Epo production and this proportion increased to 50% in stage 3. Inappropriate Epo production was seen in 60% of patients with renal impairment but was also observed in a number of patients with normal renal function. Erythropoiesis correlated strongly with the adequacy of Epo production, particularly in advanced disease. We conclude that most myeloma patients have defective red cell production even in the absence of massive marrow infiltration and that inappropriate Epo production contributes to their anaemia.
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PMID:Erythropoiesis in multiple myeloma: defective red cell production due to inappropriate erythropoietin production. 148 51

We have recently demonstrated that the CD24 antigen density of bone marrow (BM) lymphoid cells discriminates between pre-B cells and mature B-cells. Using this new method, we evaluated the B-cell lineage in the BM and peripheral blood (PB) of 18 patients with multiple myeloma (MM). First, the percentage of pre-B cells was significantly reduced by 40% in the BM of patients with MM: 2.3% +/- 2.2% versus 5.7% +/- 2.8% of normal BM lymphoid cells (P less than 0.01). This finding was associated with a significant reduction (50%) of the percentage of mature B-cells in both BM and PB, especially in patients with progressive disease (P less than 0.05). In contrast to what has been reported previously, we have not found any pre-B cells in the PB of these patients with MM. Secondly, BM pre-B and B-cell patients with MM did not express any activation markers (CD23, CD25, or CD71 antigens) and no CD5+ B-cells were found in the BM unlike in PB (8% CD5+ B-cells). Taken together, these data do not support the concept of a direct involvement (i.e, expansion or activation) of pre-B cells in MM without excluding the possibility of an early oncogenic event at the pre-B cell stage. Furthermore, our data emphasize this important reduction of the B-cell compartment (including that of pre-B cell) as a major cause of the humoral immunodeficiency in MM.
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PMID:No expansion of the pre-B and B-cell compartments in the bone marrow of patients with multiple myeloma. 190 6

The construction, synthesis and secretion of a genetically engineered antibody-cytokine fusion molecule is described. To target tumor necrosis factor (TNF) to tumor cells, recombinant antibody techniques were used to produce a Fab-like antibody-TNF conjugate. At the gene level, the heavy chain gene of an antitransferrin receptor antibody was linked to a synthetic TNF gene encoding human TNF. Transfection of the heavy chain-TNF gene into a myeloma derived cell line which was producing the light chain of the same antibody, allowed the isolation of a cell line secreting a fusion protein of the expected molecular weight and composition. The culture supernatant of the cell line contained TNF cytotoxic activity towards murine L929 cells and human MCF-7 cells. Cytotoxicity towards the human cancer cells was inhibited by an excess of the original antitransferrin receptor antibody, indicating that the antibody-TNF molecules are targeted to the transferrin receptor rich tumor cells. Since the antibody genes used are chimeric (i.e. composed of mouse variable and human constant regions) and since DNA encoding human TNF was used, the hybrid protein is an example of a humanized immunotoxin-like molecule. These results illustrate the possibilities of antibody engineering technology to create and produce improved agents for cancer therapy. Furthermore, they demonstrate for the first time the ability of myeloma cells to secrete an antibody-cytokine chimeric molecule.
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PMID:Targeting of tumor necrosis factor to tumor cells: secretion by myeloma cells of a genetically engineered antibody-tumor necrosis factor hybrid molecule. 206 6

An enzyme-linked immunosorbent assay using specific monoclonal antibodies was used to measure circulating transferrin receptor (TR) in 87 patients with various hematologic malignancies. The mean serum TR was significantly elevated in patients with myeloproliferative disorders (15.47 +/- 12.54 micrograms/ml), whereas there were no differences in chronic granulocytic leukemia (7.89 +/- 3.56 micrograms/ml), myelodysplastic disorders (9.25 +/- 4.73 micrograms/ml), and acute nonlymphocytic leukemia (3.85 +/- 3.50 micrograms/ml) as compared to normal (5.63 +/- 1.42 micrograms/ml). Among patients with lymphoproliferative disorders, the mean level was normal in lymphoma (5.73 +/- 2.59 micrograms/ml), multiple myeloma (5.47 +/- 1.31 micrograms/ml), and hairy cell leukemia (7.04 +/- 3.69 micrograms/ml). The serum TR was significantly elevated in chronic lymphocytic leukemia (CLL; 14.17 +/- 12.29 micrograms/ml), and the serum levels reflected the clinical stage of the disease. These findings suggest that serum TR measurement may provide a useful laboratory index of disease activity in certain disorders such as CLL, whereas it most likely reflects the intensity of erythropoiesis in the remaining hematological disorders that were evaluated in this study.
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PMID:Serum transferrin receptor measurements in hematologic malignancies. 216 85

Using a serum-free defined medium, we have established a human cell line, NCI-H929, from a malignant effusion occurring in a patient with IgAk myeloma. The cultured cells have the morphologic, ultrastructural, biochemical, immunologic, and cytochemical features of plasma cells. The cells have rearranged alpha and kappa genes and synthesize and secrete high amounts of IgAk (greater than 80 micrograms/10(6) cells per 24 hours). The cells express surface immunoglobulin (alpha and kappa), the plasma cell antigen PCA-1, the transferrin receptor (T9) and T10 but lack antigens associated with earlier stages of B cell development (HLA-DR, B1, B2, B4, CALLA), as well as other leukocyte-macrophage antigens and Epstein-Barr virus (EBV) nuclear antigen. Although molecular studies confirm that both the tumor and cultured cells are derived from the same clone of malignant B cells, the tumor cells were predominantly near-diploid, whereas the cultured cells are predominantly near-tetraploid with six copies of chromosome 8, four to six of which have an 8q + abnormality. However, both the tumor and the cultured cells have a rearrangement of the cellular c-myc proto-oncogene (located at 8q24) and express c-myc RNA. Although a modest number of human "plasmacytoid" cell lines have been established, most are lymphoblastoid lines lacking plasma cell features, while others appear to be early secretory cells. In contrast, NCI-H929 is a differentiated, highly secretory human plasma cell line.
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PMID:Establishment and characterization of a human plasma cell myeloma culture having a rearranged cellular myc proto-oncogene. 242 57

A mouse monoclonal IgG2a antibody, designated MRC OX-26, is shown to be specific for the rat transferrin receptor, but does not block transferrin binding. The antibody labelled a myeloma, three leukaemia cell lines and normal dividing cells of various types, but also bound to a number of nondividing normal tissues. No labelling of lymphopoietic stem cells could be detected, even though approximately 25% of bone marrow and over 95% of fetal liver cells were clearly labelled.
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PMID:Analysis of lymphopoietic stem cells with a monoclonal antibody to the rat transferrin receptor. 298 66

We previously purified the murine transferrin receptor from cultured myeloma cells and determined the amino acid sequence of six tryptic peptides. We now report the cloning of cDNA encoding the murine transferrin receptor. A tryptic peptide containing a region of six consecutive amino acids, all encoded by four or fewer codons, was used to design two overlapping oligonucleotide probes, 17 and 14 nucleotides in length. These probes were used to screen a lambda gt10 cDNA library from NS-1 myeloma cells. Of approximately 400,000 plaques screened, two hybridized strongly to both probes. A subfragment of one clone that hybridized with both oligonucleotide probes was found to encode the tryptic peptide from which the probes were derived, as well as another sequenced tryptic peptide. Comparison of the sequence with that of the human transferrin receptor shows a high degree of conservation of the sequences surrounding and penetrating the membrane, including cysteine residues that may be involved in interchain disulfide bonding and/or covalent attachment of lipid. The current data, when combined with the published sequence of the human receptor, allow assignment of all six tryptic peptides to a single chain, supporting the idea that the receptor is a homodimer. A 4.9-kb messenger RNA was found in several cultured murine and human tumor cell lines, but transferrin receptor messenger RNA was not detectable in murine spleen. An additional RNA species of 2.7 kb was present in approximately equal abundance in the murine myelomas NS-1 and C118 but was absent from T lymphomas TIKAUT, ST-1, and ST-4.
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PMID:cDNA cloning of the murine transferrin receptor: sequence of trans-membrane and adjacent regions. 298 91

The recycling itinerary of plasma membrane transferrin receptors (TFR) was charted in IgG-secreting mouse myeloma cells (RPC 5.4) by tagging surface receptors with either bound anti-transferrin receptor antibodies (anti-TFR) or Fab fragments thereof and determining the intracellular destinations of the tagged receptors by immunocytochemistry. By immunofluorescence, TFR tagged with either probe were seen to be rapidly internalized and translocated from the cell surface to the juxtanuclear (Golgi) region. When localized by immunoperoxidase procedures at the electron microscopic level, the anti-TFR-labeled receptors were detected in all cisternae (cis, middle, and trans) of the Golgi stacks as well as in endosomes and trans Golgi reticular elements. There was no difference in the routing of TFR tagged with monovalent Fab and those tagged with divalent IgG. Tagged receptors were detected in Golgi stacks of approximately 50% of the cells analyzed. The position of the labeled cisternae within a given stack was found to be quite variable with cis and middle cisternae more often labeled at 5 min and trans cisternae at 30 min of antibody uptake. The finding that recycling plasmalemmal TFR can visit all or most Golgi subcompartments raises the likely possibility that any Golgi-associated posttranslational modification can occur during recycling as well as during the initial biosynthesis of plasmalemma receptors and other membrane proteins.
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PMID:Transferrin receptors recycle to cis and middle as well as trans Golgi cisternae in Ig-secreting myeloma cells. 301

Circulating transferrin receptor has been detected in human serum with a sensitive immunoassay. The mean concentrations of the serum transferrin receptor in healthy males and females were 251 +/- 94 (mean +/- SD) ng/ml and 256 +/- 99 ng/ml, respectively. The serum receptor concentration in patients with haematological malignancies, including acute leukaemia, multiple myeloma and malignant lymphoma, varied widely, from normal to 1100 ng/ml. A single band with an approximate molecular weight between 80,000 and 100,000 daltons was obtained by polyacrylamide gel electrophoresis-immunoblotting analysis of serum.
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PMID:Circulating transferrin receptor in human serum. 377 24

BALB/c mice were injected with an affinity-chromatography-purified placental transferrin receptor preparation. Spleen cells were fused with NS-1 myeloma cells. Sixteen hybrids producing monoclonal antibodies specific for the transferrin receptor and two hybrids specific for transferrin were identified by radioimmunoassay (RIA). Five hybrids were selected for cloning on the basis of antibody specificity and affinity. None of the antibodies inhibited the binding of transferrin to K562 cells. The binding of antibody ID9 to K562 cells was partially inhibited by transferrin or a polyclonal goat anti-transferrin receptor antiserum. Of the five antibodies, two (IIB6 and IIB2) reacted only with the purified receptor and solubilized cells and not with whole cells. The other three antibodies, when tested with normal human cells and leukaemia and tumour cell lines, showed identical reaction patterns. The antibodies precipitated a glycoprotein from K562 cells with an apparent molecular weight of 94,000, estimated from sodium dodecyl sulphate-polyacrylamide gel electrophoretograms run under reducing conditions, and a molecular weight of 188,000 when run under unreduced conditions. All antibodies have a high affinity with Ka values ranging from 1.44 X 10(9) to 3.56 X 10(10) (l/mol). The antigen precipitated by all five antibodies showed identical peptide maps after partial proteolytic digestion.
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PMID:Monoclonal antibodies to a purified human transferrin receptor. 609 40


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