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Biomedical subjects

K Iwato

Publications and source records attributed to K Iwato.

30 records · Page 2Linked to original sources
PubMed1989

BSF-2/IL-6 does not augment Ig secretion but stimulates proliferation in myeloma cells.

Human myeloma cells were highly purified from bone marrow aspirates of 21 patients with advanced immunoglobulin G (IgG)-type multiple myeloma. B-cell stimulatory factor 2 (BSF-2)/interleukin-6 (IL-6) was originally characterized as a cytokine that can enhance immunoglobulin secretion from activated normal B cells and increase the expression of secretory-type Ig mRNA in these B cells, but that does not augment proliferation of activated B cells. However, recombinant IL-6 (rIL-6) could not enhance M-protein (IgG) secretion in freshly isolated myeloma cells in vitro but could augment proliferation of myeloma cells, although myeloma cells constitutively expressed IL-6 receptors. Furthermore, expression of secretory-type IgG (gamma-chain) mRNA in myeloma cells was not changed in the presence of IL-6. These results show that IL-6 is not an enhancing factor in Ig secretion from myeloma cells, and thus signal transduction through IL-6 in myeloma cells may be altered as opposed to activated B cells.

Adjuvants, Immunologic↗
PubMed1989

Heterogenous response of B cell chronic lymphocytic leukaemia (B-CLL) cells to anti-human IgM antibody (anti-mu) and B cell stimulatory factor 1 (BSF-1).

B cell chronic lymphocytic leukaemia (B-CLL) cells from seven patients were examined for 3H-TdR uptake with anti-human IgM antibody (anti-mu) and B cell stimulatory factor 1 (BSF-1)/IL-4. B-CLL cells from one patient could proliferate with anti-mu plus BSF-1, but not with BSF-1 alone. B-CLL cells from two patients responded to BSF-1 alone; one could proliferate more by adding anti-mu, but the proliferation of the other cells was inhibited by adding anti-mu. On the other hand, B-CLL cells from the other four patients responded neither to anti-mu nor to anti-mu plus BSF-1. Surface densities of membrane IgM of B-CLL cells were also analysed by fluorescence activated cell sorter (FACS), but there was no correlation between proliferative response (DNA synthesis) of B-CLL cells to anti-mu and densities of surface membrane IgM. These results show that there is a functional heterogeneity of B-CLL cells with regard to proliferative response to anti-mu and BSF-1.

Aged↗
PubMed1989

[A case of refractory multiple myeloma demonstrating a relationship between the progression of the disease and in vitro myeloma cells activity].

In vitro proliferation (3H-TdR-uptake) and M-protein secretion rate by highly purified myeloma cells from bone marrow aspirates were examined serially to evaluate the progression of multiple myeloma in a patient who was refractory to conventional alkylating agents. Following the administration of IFN-alpha, serum M-protein decreased significantly, with the reduced in vitro spontaneous M-protein secretion rate from the separated myeloma cells. Similarly, when IFN-alpha as low as 10 u/ml was added in vitro, it also suppressed M-protein secretion from myeloma cells of this patient, suggesting that, the observed decrease of serum M-protein was due to diminished M-protein secretion by the myeloma cells themselves, as well as the reduction of the tumor cell burden. On the other hand the in vitro 3H-TdR uptake by the myeloma cells increased markedly with the decrease in the M-protein secretion rate. Five months after the initiation of IFN-alpha treatment, tumor formation at the lumbar vertebrae occurred when serum M-protein level was still low, followed by a bone marrow relapse. These results suggest that serial assessments of proliferation and M-protein secretion potential of myeloma cells in vitro can be helpful in predicting the progression of multiple myeloma.

Cell Division↗
PubMed1989

Interleukin-1 accelerates autocrine growth of myeloma cells through interleukin-6 in human myeloma.

Recombinant interleukin 1 alpha (rIL-1 alpha) augmented proliferation of freshly isolated myeloma cells as well as B-cell stimulatory factor 2 (BSF-2)/interleukin-6 (IL-6). Recombinant IL-1 alpha-induced proliferation was partially inhibited by anti-IL-6 antibody. In the culture supernatants of rIL-1 alpha-stimulated myeloma cells, IL-6 activities, which were measured by using an IL-6-dependent murine hybridoma clone, MH60.BSF2, were increased, when compared with those in the culture supernatants of nonstimulated myeloma cells. Furthermore, IL-6 messenger RNA (mRNA) expression was also augmented in IL-1 alpha-stimulated myeloma cells. Therefore rIL-1 alpha stimulates myeloma cells to produce IL-6, which consequently augments proliferation of myeloma cells. Thus, IL-1 can accelerate autocrine growth of myeloma cells through IL-6.

Adjuvants, Immunologic↗
PubMed1989

Sensitive inhibitory effect of interferon-alpha on M-protein secretion of human myeloma cells.

The effects of interferon-alpha (IFN alpha) on in vitro proliferation and M-protein secretion in human myeloma cells were investigated. Human myeloma cells were purified from bone marrow aspirates in 12 multiple myeloma patients. Purified myeloma cells were cultured for 48 hours with IFN alpha at its lower concentrations (0.1 to 100 U/mL). The cells were then pulsed with 3H-TdR for the last 12 hours and 3H-TdR uptake was measured (in vitro proliferation). After 48-hour culture, supernatants were harvested and the amount of M-protein in these fluids were measured by enzyme-linked immunosorbent assay (ELISA) (in vitro M-protein secretion). In vitro M-protein secretions of myeloma cells were significantly suppressed even at 0.1 U/mL of IFN alpha, while 3H-TdR uptakes were not so suppressed until 10 or 100 U/mL of IFN alpha were added. The expressions of secretory immunoglobulin (Ig) mRNA of these myeloma cells were also selectively suppressed by IFN alpha. Furthermore, after IFN alpha had been administered intramuscularly, 3 to 6 x 10(6) U/d for at least 1 month, in vitro M-protein secretions of these myeloma cells were decreased compared with those before IFN alpha administration. Therefore, these results suggest that IFN alpha has more sensitive inhibitory effect on M-protein secretion of human myeloma cells rather than on myeloma cell proliferation.

Blood Proteins↗
PubMed1988

Autocrine generation and requirement of BSF-2/IL-6 for human multiple myelomas.

Human B cell stimulatory factor 2 (BSF-2) was originally characterized and isolated as a T cell-derived factor that caused the terminal maturation of activated B cells to immunoglobulin-producing cells. Molecular cloning of the complementary DNA predicts that BSF-2 is a protein of relative molecular mass (Mr) 26,000 similar or identical to interferon beta 2, hybridoma plasmacytoma growth factor and hepatocyte stimulating factor. IL-6 has been proposed as a name for this molecule. It is now known that BSF-2 has a wide variety of biological functions and that its target cells are not restricted to normal B cells. Responses are also seen in T cells, plasmacytomas, hepatocytes, haematopoietic stem cells, fibroblasts and rat phoeochromocytoma, PC12 (Satoh, T. et al., manuscript in preparation). Of particular interest to this report is that human BSF-2 is a potent growth factor for murine plasmacytomas and hybridomas. This observation suggested to us that constitutive expression of BSF-2 or its receptor could be responsible for the generation of human myelomas. In this study we report that myeloma cells freshly isolated from patients produce BSF-2 and express its receptors. Moreover, anti-BSF-2 antibody inhibits the in vitro growth of myeloma cells. This is direct evidence that an autocrine loop is operating in oncogenesis of human myelomas.

Antibodies↗
PubMed1988

Decrease in BSF-2/IL-6 response in advanced cases of multiple myeloma.

Human myeloma cells freshly isolated from 40 patients with IgG multiple myeloma (MM, 10 in stage I and 30 in stage III), were cultured for 48 hours with recombinant B cell stimulatory factor 2 (rBSF-2)/interleukin-6 (IL-6), which is considered a major growth factor for myeloma cells. Uptake of 3H-thymidine by these purified myeloma cells was measured, and BSF-2 response was evaluated by stimulation index and delta cpm induced by rBSF-2. Myeloma cells from cases in stage I responded to rBSF-2 better than those in stage III. Moreover rBSF-2 responders also showed better response to chemotherapy. Therefore, these results suggest that in vitro response of myeloma cells to BSF-2 correlates with disease progression and clinical response in patients of MM.

Humans↗
PubMed1988

Separation of human myeloma cells from bone marrow aspirates in multiple myeloma and their proliferation and M-protein secretion in vitro.

Human myeloma cells were purified from bone marrow aspirates from patients with multiple myeloma (MM) by Percoll discontinuous density-gradient centrifugation, E rosette formation and treatment with antimyelomonocytic antibody (Leu M1), plus complement. Thus, the purified cell fraction consisted of greater than 90% myeloma cells, even when as little as 15% myeloma cells were contained in bone marrow mononuclear cell fraction, determined by morphological and immunologic examinations. With highly purified myeloma cells from 29 patients with IgG type MM, biologic characteristics such as spontaneous proliferation (3H-TdR uptake) and M-protein secretion rate in vitro were evaluated. Both activities varied among patients within stage I and III, and a 3H-TdR uptake of 255-24, 132 cpm/4 x 10(4) cells, and an M-protein secretion rate of 9 to 72 pg/cell/day, respectively, were recorded. However, in each patient, there was no correlation between 3H-TdR uptake and M-protein secretion rate. These results thus suggest that 3H-TdR uptake and M-protein secretion rate of highly purified myeloma cells are independent biologic parameters, not associated with the clinical stages, and the purification of myeloma cells we describe can contribute to further studies on the biologic characteristics and to understanding of the pathophysiology involved in MM.

Blood Proteins↗
PubMed1985

Identification and characterization of a B cell growth inhibitory factor (BIF) on BCGF-dependent B cell proliferation.

The culture supernatants of Con A-activated human peripheral blood mononuclear cells (PBM) contained at least two regulatory factors upon B cell proliferation. One was B cell growth factor (BCGF), which activated antigen-stimulated B cells to proliferation and clonal expansion, and the other was its inhibitory factor, arbitrarily named B cell growth inhibitory factor (BIF). This BIF inhibited the effect of BCGF on anti-mu-stimulated B cells or the monoclonal mature B cell line (CLL-T.H.) obtained from the peripheral blood lymphocytes of B cell-type chronic lymphocytic leukemia patients, which were activated only with BCGF and without adding other proliferating stimuli (e.g., anti-mu). BIF activity was detected in the 24 hr culture supernatants of Con A-activated human PBM in FCS containing medium and also in serum-free RPMI 1640 medium. This substance with BIF activity could not be derived from FCS. Con A-induced BIF (m.w. of 80,000 and an isoelectric point of pH 5.4) was analyzed by Sephadex G-200 gel filtration and chromatofocusing. BIF was stable at pH 2.0 and at 56 degrees C for 30 min. Partially purified BIF had no effect on cell viability and almost no interferon activity (less than 1 IU/ml). BIF with high titer had a slight but significant inhibition on TCGF-dependent T cell growth and on PHA or Con A responses, but the extent of these inhibitions was far less than that of BCGF-dependent B cell growth. Absorption of BIF with Con A blasts made its inhibition on T cell growth even less. On the other hand, BIF activity could not be absorbed with Con A blasts but was almost absorbed with large numbers of CLL-T.H. cells. BIF had almost no inhibitory effect on the proliferation of a mouse fibroblast cell line (NIH 3T3), a mouse myeloma cell line (NS-1), human lymphoid cell lines (MOLT-4, HSB-2, and Daudi), or a human myeloid cell line (K-562). BIF-producing cells were estimated to be T cells and were identified as T8+ T cells. On the other hand, Con A-induced BCGF was demonstrated to be produced predominantly by T4+ T cells. These results show that human B cell proliferation is regulated by interaction between T4+ and T8+ cells via soluble factors, namely BCGF and BIF, respectively.

Animals↗