Yoshiaki Okuno

Erythropoietin receptor of a human leukemic cell line with erythroid characteristics.

A new cell line of human erythroleukemia cells differentiates spontaneously so that 30% of the cells are always hemoglobinized. Erythropoietin did not affect the percentage of such cells but stimulated the cell growth, indicating that the cells have functioning receptors. Binding of human recombinant radioiodinated erythropoietin to the receptors was specific. The bound ligand was internalized into cells at 37 degrees C but not at 15 degrees C. Scatchard analysis showed two classes of binding sites. Covalent binding of erythropoietin to its receptors yielded two products detected on sodium dodecyl sulfate-polyacrylamide gels electrophoresed under reducing conditions. Under non-reducing conditions, these species disappeared and larger products appeared.

Liver damage in patients with colony-stimulating factor-producing tumors

PURPOSE We have demonstrated that colony-stimulating factor (CSF)-producing tumor cell lines produce not only CSF but also interleukin-1 (IL-1) and interleukin-6 (IL-6). Clinically, we have observed that patients bearing such tumors present with liver dysfunction and fever in addition to marked leukocytosis. The purpose of this study was to determine whether or not the liver damage was specifically related to CSF-producing tumors. PATIENTS AND METHODS Clinicopathologic examinations were performed in six autopsied patients with CSF-producing tumors. We also transplanted two tumor cell lines (KHC287 and CHU-2), which produce granulocyte (G)-CSF, IL-1, and IL-6, to nude mice. RESULTS Of the six patients, five had G-CSF- and one had granulocyte/macrophage (GM)-CSF-producing tumors. IL-1 and IL-6 concentrations in plasma or culture supernatant were elevated in these patients. Biochemical examinations revealed high serum enzyme levels of the biliary system in contrast to normal or slight increases in transaminase levels in all patients studied. Serum direct bilirubin was elevated in five of the six patients. Three common pathologic changes of the liver were found: (1) focal necrosis associated with neutrophil infiltration in the centrilobular zones, (2) fibrous change and enlargement of the portal area associated with neutrophil infiltration, and (3) intrahepatic cholestasis. The same pathologic changes, except for cholestasis, were reproduced in the liver of mice transplanted with KHC287 or CHU-2. CONCLUSION These results indicate that patients with CSF-producing tumors have characteristic liver damage, and suggest a new paraneoplastic syndrome of leukocytosis and liver damage.

Expression of the erythropoietin receptor on a human myeloma cell line.

We demonstrated the expression of the erythropoietin (EPO) receptor by a human myeloma cell line (MM-S1) which was established in our laboratory. EPO dose-dependently stimulated the proliferation of MM-S1 cells. Binding of radioiodinated EPO (125I-Epo) to MM-S1 cells was competitively inhibited by unlabeled EPO, but not by other recombinant cytokines. Specific binding of 125I-Epo to MM-S1 cells was saturable, and the Scatchard analysis revealed 330 EPO binding sites per cell with a Kd of 0.56 nmol/L. Bound EPO was internalized by MM-S1 cells during incubation at 37 degrees C. This is the first report describing the expression of the EPO receptor by human cells other than those of the erythroid lineage.

IL-1 production as a regulator of G-CSF and IL-6 production in CSF-producing cell lines.

We previously demonstrated that colony stimulating factor (CSF)-producing cell lines co-produce interleukin-1 (IL-1) and IL-6 in addition to CSFs. In the present study, we examined the role of IL-1 production in three human tumour cell lines producing granulocyte (G)-CSF, IL-1 and IL-6. Addition of anti-human IL-1 alpha antiserum to the culture caused a 90-62% reduction of G-CSF and a 85-44% reduction of IL-6 production, respectively, as evaluated by enzyme immunoassay in all three cell lines. The decrease of G-CSF and IL-6 production by the anti-IL-1 alpha antiserum was also confirmed at the level of mRNA expression. The anti-IL-1 alpha antiserum did not affect the growth of these cell lines. Excess recombinant IL-1 alpha exogenously added to the culture enhanced G-CSF and IL-6 production in all three cell lines. However, IL-1 alpha had little effect on the growth of these three cell lines. Neither anti-IL-6 nor anti-G-CSF antibodies affected the production of the other cytokines. These results indicate that IL-1 alpha regulates G-CSF and IL-6 production in these tumour cell lines, and suggest that the IL-1 production plays an important role in CSF-producing tumours.

Megakaryocyte potentiating activity of IL‐1, IL‐6 and GM‐CSF as evaluated by their action on in vitro human megakaryocytic colonies

Summary We examined whether recombinant cytokines enhance the in vitro platelet production of interleukin‐3 (IL‐3)‐induced human megakaryocytic colonies (Meg‐colony). We classified Meg‐colonies into four categories based on platelet production during in situ observation on day 14: type 0, absence of cytoplasmic processes in a colony; type 1, one to three processes in at least one megakaryocyte in a colony; type 2, four to eight processes; type 3, more than nine processes or division of cytoplasm. Type 3 colonies were considered to be platelet‐producing. In control cultures, type 1 Meg‐colonies were dominant, followed by type 2, type 3 and type 0. Of the cytokines added at the initiation of culture, interleukin‐1 alpha (IL‐1α), interleukin‐6 (IL‐6), and granulocyte/macrophage colony stimulating factor (GM‐CSF) significantly increased the number of colonies. Furthermore, these three cytokines significantly elevated the proportion of type 3 colonies. Interleukin‐4 (IL‐4), granulocyte‐CSF, macrophage‐CSF and erythropoietin did not affect the colony count or distribution of colony type. IL‐1α. IL‐6 and GM‐CSF also significantly elevated the proportion of type 3 colonies, even when added to the culture on days 8 or 11. These results indicate that IL‐1α, IL‐6 and GM‐CSF promote platelet production of in vitro Meg‐colonies.

Establishment of an erythroid cell line (JK‐1) that spontaneously differentiates to red cells

The authors established a new hemopoietic cell line (JK‐1) from a patient with chronic myelogenous leukemia in erythroid crisis. This JK‐1 line predominantly consists of immature cells, but a small number of mature erythroblasts and red cells can be consistently seen without any specific differentiation inducer. The JK‐1 cells grow in suspension culture supplemented with human plasma and carry double Philadelphia chromosomes. Hemoglobin staining with benzidine was positive for about 20% of cells and the type of the hemoglobin was for the most part HbF. Surface‐marker analysis revealed JK‐1 cells positive for glycophorin A, EP‐1, and HAE9. The proportion of mature cells was elevated by the addition of δ‐aminolevulinic acid. Erythropoietin (EPO) enhanced the growth of JK‐1 cells either in the suspension or in methylcellulose semisolid culture. The total number of EPO receptors was 940 per cell, of which 220 sites had an affinity higher than the other 720 sites. This is the first report of an established human erythroid cell line which spontaneously undergoes terminal differentiation.

Mechanism in 1,25(OH)2D3-induced suppression of helper/suppressor function of CD4/CD8 cells to immunoglobulin production in B cells

On the basis of previous data that 1,25(OH)2D3 suppressed both helper and suppressor activities of CD4 and CD8 cells in the pokeweek mitogen-stimulated culture, we examined the further effect of 1,25(OH)2D3 on both cells to define how 1,25(OH)2D3 is involved in the deterioration of their functions. 1,25(OH)2D3 suppressed the pokeweed mitogen and phytohemagglutinin-induced DNA synthesis of CD4 and CD8 cells. The suppression by 1,25(OH)2D3 of DNA synthesis was caused by a time lag in reaching maximal response. 1,25(OH)2D3 also suppressed interleukin-2 production of CD4 and CD8 cells. 1,25(OH)2D3 did not, however, affect their interleukin-2 receptor expression detected within 24 hr after phytohemagglutinin stimulation. In addition, 1,25(OH)2D3 failed to suppress DNA synthesis of CD4 and CD8 cells when cultured with a large amount of interleukin-2. Suppression by 1,25(OH)2D3 of proliferation and interleukin-2 production in CD4 and CD8 cells would bring about the decrease of their helper or suppressor functions by inhibiting their expansion or maturation.

Estimation of interleukin 6 production by reverse transcriptase-polymerase chain reaction in four human myeloma cell lines

Although an autocrine growth mechanism through interleukin 6 has been advocated in human myeloma cells, reports of IL-6 production by cells from established myeloma cell lines are rare. In the present study, we examined whether or not a minute amount of interleukin 6 is produced in 4 human myeloma cell lines. IL-6 production was not detected in any of the 4 lines by enzyme immunoassay, bioassay with two interleukin 6-dependent murine hybridoma cell lines and Northern hybridization. However, we detected interleukin 6 mRNA in one (U266) of the 4 lines by the reverse transcriptase-polymerase chain reaction. Nevertheless, the proliferation of all 4 lines was not inhibited by an anti-interleukin 6 antibody. These results suggest that autocrine stimulation by interleukin 6 is not involved in the majority of human myeloma cell lines.