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Relationship of surface immunoglobulin-bearing cells, plasma cells, and tumor development in anaplastic carcinoma-bearing A/J mice.

Since the humoral immune response has been shown to be associated with immunological enhancement of tumor growth, the study of surface immunoglobulin-bearing cells and plasma cell antigen (PCA)-bearing cells during neoplastic development may provide new approaches to the study of tumor immunology. Peripheral blood was collected every other day from normal and carcinoma-bearing mice. Lymphocytes obtained by Ficoll-Hypaque density centrifugation were assayed for immunoglobulin-bearing cells and PCA-bearing cells using either fluorescein-conjugated goat anti-mouse immunoglobulin or rabbit anti-mouse plasma cell serum and fluorescein-conjugated goat anti-rabbit immunoglobulin. A marked increase in immunoglobulin-bearing cells from tumor-bearing mice was observed by Day 6 and peaked at Day 10. An increase in PCA-bearing cells followed the immunoglobulin-bearing cells increas by 2 to 4 days. The immunoglobulin-bearing cells declined by Day 12, whereas PCA-bearing cells remained elevated through Day 20. Using rabbit anti-mouse plasma cell serum as an immunosuppressive agent, a 4-day prolongation of the mean survival time was observed in rabbit anti-mouse plasma cell serum-treated tumor-bearing mice. This suggests that tumor growth in this model may be related to an active humoral immune response and that suppression of the plasma cell population may prove to be beneficial in the treatment of certain tumors.

Animals

Expression of IgGFc receptors on human plasma cells.

Plasma cells that were obtained in bone marrow aspirates from patients with plasma cell dyscrasias were assessed for the expression of IgGFc receptors. A sensitive EA rosette assay and direct immunofluorescence were combined to quantitate plasma cells that expressed IgGFc receptors. Two patients with nonsecretory disorders had large numbers of receptor positive cells (98 and 78%). The remaining patients, all of which had been treated with cytotoxic drugs prior to testing, had significant numbers of IgGFc receptor positive cells (36-86%) and the number of FC receptor positive cells was increased by storing the cells at 4 degrees C for 18 hours prior to performing the rosette assay.

Humans

DIS3 licenses B cells for plasma cell differentiation in humans.

DIS3 is the main catalytic subunit of the nuclear RNA exosome, a complex playing a crucial role in RNA processing and the degradation of various noncoding RNA substrates. In mice, DIS3 is essential for genomic rearrangements during B cell development, but its role in terminal plasma cell (PC) differentiation has not been explored. Although DIS3 gene alterations are frequent in multiple myeloma (MM), a PC malignancy, their molecular impact remains poorly understood. In this study, we developed an antisense oligonucleotide strategy to knock down DIS3 expression in a well-characterized model of human PC differentiation. Reducing DIS3 expression systematically led to decreased B cell proliferation and impaired PC differentiation with lower levels of switched immunoglobulin secretion. Transcriptome analyses confirmed alterations in the proliferation and differentiation programs, alongside an accumulation of noncoding RNAs. Notably, centromere-associated noncoding RNAs were highly sensitive to DIS3 activity, and their accumulation in DIS3-deficient cells, either as transcripts or DNA-associated RNAs, correlated with the mislocalization of the centromere-specific histone variant CENP-A. We finally observed reduced physiological DNA recombination and somatic hypermutation but increased genomic instability in DIS3-deficient cells, in agreement with the higher levels of IGH translocations observed in our large cohort of DIS3-mutant MM patients. Together, these results underscore the essential role of DIS3 in regulating B cell proliferation, DNA recombination, and physiological or malignant PC differentiation in humans.

Humans

Needle-like crystals in plasma cells in a patient with a plasma cell proliferative disorder.

A patient with a plasma cell proliferative disorder and a monoclonal IgG-kappa protein in the serum was observed over a period of four years. Two unusual features were seen in this patient: (1) An apparently benign course in spite of relatively large and slowly increasing amounts of Bence Jones protein (monoclonal kappa light chains) in the urine, and (2) crystalline structures located outside the cisternae of the endoplasmic reticulum in a large number of bone marrow plasma cells. The crystals, which ultrastructurally appeared to be composed of protein material, were not stained by immunofluorescent antisera to immunoglobulins. They were, however, observed only in cells staining for gamma heavy and kappa light chains. This suggest an association between the crystalline structures and the synthesis of monoclonal immunoglobulin proteins.

Bence Jones Protein

Immunologic studies of human plasma cells.

Purified plasma cell suspensions were produced from 3 subjects with malignant plasma cell disease. Various physical, biological, and immunological properties of these cells were studied. Neoplastic human plasmablasts were found to be denser than their mature forms, in contrast to the usual relationship of the lymphoid, myeloid, and erythroid series. The human plasma cells did not respond to phytohemagglutinin stimulation and were found to be weakly reactive in mixed lymphocyte-plasma cell cultures. Potent antisera was produced against such cells, and the antisera demonstrated a broad cross reactivity with various human lymphocyte populations. The data suggest a lymphoid origin for human plasma cells and possibly a specific relationship to B-type lymphocytes.

Cross Reactions

Role of membrane receptors in the induction of an in vitro secondary anti-hapten response. I. differentiation of B memory cells to plasma cells is independent of antigen-immunoglobulin receptor interaction.

In these experiments, we show that the interaction of antigen and B cell surface immunoglobulin is not essential for the generation of an IgG in vitro response to the hapten p-azophenyl-lactoside (lac). In our experimental system, keyhole limpet hemocyanin (KLH) was first selectively attached either to H-2, Ia or Ig receptors of lac-primed B cells by a hapten sandwich technique or to Fc receptors by complexes of azophenyl arsonate (ars)-coupled KLH and anti-ars. The labeled cells were then cultured with KLH-specific T cells for 5 days in the absence of antigen. Under all conditions of attachment we observed a significant anti-lac IgG response. We have demonstrated an absolute requirement for KLH-specific helper T cells. The results thus indicate that T helper cells are by themselves, regardless of the B cell antigen that serves to effect bridging, sufficient to activate B memory cells. We could find no evidence to support either a matrix theory or a two-signal hypothesis as currently proposed.

Animals

Different susceptibility of protein synthesis to inhibitors of elongation in cell-free systems from plasma cell tumours and reticulocytes.

Plasma cells and reticulocytes are mammalian cell systems which have specialized in the synthesis of a single protein during their differentiation from one common stem cell. To study whether there is a difference in cell susceptibility at the level of elongation, dose vs. inhibition curves of sparsomycin, cycloheximide and emetine in cell-free systems with S-30 fractions from plasma cell tumours (MOPC 63, MOPC 41, RPC 20, MOPC 104 E), reticulocytes and liver were compared. The experiments revealed: (1) all the selected systems are equally sensitive to sparsomycin; (2) the susceptibility of the reticulocyte systems to cycloheximide and emetine is higher than that of the plasma cell tumours. In the dose range of 1 - 10(-7) --5 - 10(-5) M cycloheximide and 1 - 10(-6)--1 - 10(-4) M emetine the reticulocyte system is preferentially inhibited; (3) the sensitivities of all plasma cell tumours are equal; (4) the liver system is more sensitive to emetine than to cycloheximide; (5) the site of the different susceptibility to these antibiotics could be located on the ribosomes; (6) however, when the extracts of the plasma cell tumours were prepared in the presence of hemin, their susceptibility rises and is like that of reticulocytes. These results show that hemin promotes in a cell-specific manner the sensitivity to some inhibitors of protein synthesis.

Animals

Polyclonal activation of human B lymphocytes in vitro by pokeweed mitogen: a simple technique for the simultaneous assessment of cell proliferation, generation of plasma cells, plaque-forming cells and immunoglobulin production.

A simple technique has been worked out for the simultaneous assessment of cell proliferation, generation of plasma cells, plaque-forming cells and immunoglobulin production from single cultures of 1 X 10(6) human peripheral blood lymphocytes stimulated with pokeweed mitogen (PWM). Kinetic studies showed that number of cells, thymidine incorporation rate, number of plaque-forming cells against fluorescein-isothiocyanate-haptenated sheep erythrocytes and concentration of IgM and IgG in the supernatant peaked on the average between day 5 and 7 of culture. This technique is particularly suitable for the analysis of hypogammaglobulinaemias in infancy.

Adult

Iron-containing plasma cells.

Iron in plasma cells has been described in patients with diseases characterized by iron overload. We observed iron-containing plasma cells in 21 anemic alcoholic patients admitted to the hospital for treatment of complications of alcoholism. The presence of iron-containing plasma cells is suggestive of alcoholism and its complications, and diseases associated with iron overload or inability of RBCs to utilize iron. The mechanism of entry of iron into plasma cells is unknown.

Anemia

Enhancement by irradiated T cells of human plasma cell production: dissection of helper and suppressor functions in vitro.

The addition of irradiated T-enriched lymphocytes to B cell-enriched fractions of human peripheral blood or to unseparated mononuclear cells stimulated the differentiation of plasmacytoid cells in culture with pokeweek mitogen beyond the synergy obtained by the addition of unirradiated T cells. This stimulation was observed in both the proportion and absolute number of plasmacytoid cells recovered from the cultures, and in the amount of IgM detected in culture supernatants by a hemagglutination inhibition assay. Irradiation-induced enhancement was observed with normal and hypogammaglobulinmic T cells, but not with monoclonal T cells from two patients. Inactivation of T cells by heating or by repeated freezing and thawing did not produce the same effects as did irradiation. These data suggest that cell-mediated suppressor function in man is selectively radiosensitive, while helper activity is not. Irradiation may be a useful method for the functional isolation of helper cells and for the manipulation of the balance between suppressor and helper cell activities.

B-Lymphocytes

Induction of serum stimulation and plasma cell proliferation during chemotherapy of multiple myeloma.

Sequential sera from 45 patients with multiple myeloma (MM) and from 6 patients with solid tumors but normal bone marrows who received cyclophosphamide, 15 mg/kg/day for 4 days, were assayed for their effects on tritiated thymidine (3H-TdR) incorporation by normal bone marrow cells and malignant plasma cells. Pretreatment sera from 23 of the 45 patients with MM inhibited normal marrow cell proliferation relative to the effects of normal sera. Of these 45 sera, 30 inhibited plasma cell proliferation. This humoral inhibition was overcome by the induction of humoral stimulation at a predictable time during chemotherapy. The sera obtained sequentially from patients with MM and patients with normal bone marrows increased 3H-TdR uptake by both cell types by days 12-15 of therapy. Sequential changes in malignant marrow plasma cell 3H-TdR labeling indices paralleled the changes in serum activity, with an increased tumor cell growth fraction occurring at the time of peak serum stimulatory activity. The relationship between serum stimulation and malignant plasma cell proliferation was confirmed in vitro.

Bone Marrow

A simple technique for studying immunoglobulin synthesis by normal and malignant plasma cells in vitro.

Plasma cells from human marrows are saturated with C-14 labelled amino acids, harvested and recultured in unlabelled growth medium. The appearance of radioactivity in the growth medium then provides a simple and rapid measure of protein synthesis. The secreted radio-labelled material is characterized by isoelectric focusing and autoradiography in acrylamide gels, a technique which has advantages over established serological methods.

Autoradiography

Establishment of a human plasma cell line in vitro.

A human plasma cell line designated ARH-77 has been established and propagated in culture for the past 2 years. The cells exhibited morphological characteristics of plasma cells under light and electron microscopic examination. An average of 40% cells are positive for immunoglobulin G by direct immunofluorescence, while an immunoglobulin G-specific radioimmunoassay reveals the production of 1.21 X 10(4) ng/10(6) plasma cells. The karyotype is aneuploid with a a modal chromosome number of 45 to 46 and no marker chromosome. Growth kinetics characteristics are: doubling time, 110.4 hr; generation time, 56.4 hr; G1 + G2-phase transit time, 45.5 hr; S-phase transit time, 10.9 hr; growth fraction, 74%; mitotic index, 1.5%; labeling index, 14.3%; and cell loss, 31.0%. Some of the growth kinetics characteristics were markedly similar to the properties displayed in vivo by plasma cells of patients with multiple myeloma and suggest that the cell line might be a useful in vitro model for the study of human myeloma.

Aneuploidy

A human tubular array plasma cell.

A human plasma cell is described which is distinct with both the light and electron microscope. With indirect immunofluorescence its cytoplasm is immunoglobulin-associated and the ultrastructure is characterized by tubular arrays of endoplasmic reticulum similar to those described in a number of diseases. Hypotheses regarding these tubular structures are reviewed.

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