Characterization of factors stimulating differentiation of mouse myeloid leukemia cells from a Yoshida sarcoma cell line cultured in serum-free medium.

A clone, YS-T22, of cells from Yoshida sarcoma cell line, YSSF-212T, grown in "serum-free" culture medium produced factors stimulating differentiation of mouse myeloid leukemia cells (M1) to macrophages and granulocytes. The formation of macrophages and granulocytes was accompanied by induction of phagocytosis, locomotive activity, and lysosomal enzyme activities. The rates of induction of these differentiated phenotypes were proportional to the concentration of the factor added and the period of treatment. The factor stimulating differentiation of M1 cells was a heat-labile, nondialyzable proteinaceous substance that was inactivated by trypsin but not by ribonuclease or glycosidases. On diethylaminoethyl cellulose chromatography, the factor stimulating differentiation of M1 cells from conditioned medium of YS-T22 cells was eluted in various fractions with or without activity of the colony-stimulating factor.

Production of macrophage colony-stimulating factor by adult murine parenchymal liver cells (hepatocytes).

The activity of macrophage colony-stimulating factor (M-CSF) was found in the culture supernatant of mouse parenchymal liver cell fractions in a bone marrow colony-forming assay. The activity of an M-CSF-like substance purified by a four-step procedure was neutralized by goat anti-mouse M-CSF antiserum. M-CSF mRNA was detected in cellular RNA prepared from cultured parenchymal liver cell fractions by Northern blot analysis and also in cultured parenchymal liver cells by in situ hybridization. These results indicate that parenchymal liver cells have the capacity to produce M-CSF. We discuss the role of M-CSF in hematopoiesis, the immune response, and other biological phenomena.

Specificity of the suppressive action of glucocorticoids on the proliferation of monocyte/macrophages in the CSF-stimulated cultures of mouse bone marrow.

Addition of cortisol and its analogs to soft-agar culture of bone marrow cells markedly decreased the number of monocyte colonies in the presence of colony-stimulating factor. Steroids of other categories and cortisol metabolites were much less inhibitory than cortisol, and the shape of dose-response curve apparently differed between cortisol and other steroids. The action of cortisol was not influenced by excess progesterone or testosterone. Addition of cortisol succinate in liquid cultures of CSF-stimulated cells caused a gradual decrease of cellular uptake of [3H]thymidine. The steroid also suppressed CSF-independent [3H]thymidine uptake, but the time course of suppression obviously differed from that of CSF-dependent uptake. On day 7 of incubation, the steroid-treated cultures contained a smaller number of cells but higher activities of lysosomal enzymes than the control cultures. These results show that the glucocorticoids inhibit proliferation of the cells of monocyte/macrophage lineage.

Enhancement of the action of colony stimulating factor (CSF) by soluble component(s) of erythrocytes in mouse bone marrow cells cultures.

Rat erythrocytes, separated from other blood cells by SE-cellulose chromatography, were lysed by exposure to hypotonic solution, dialyzed and ultracentrifuged. The supernatant contained a substance which enhanced the activity of colony stimulating factor (CSF) in soft agar cultures of granulocyte-macrophage progenitor cells (CFU-C) from normal mouse bone marrow. The growth-enhancing effect of the erythrocyte factor was observed when mouse L-cell conditioned medium was used as the CSF source and also when serum from endotoxin-treated mice or from mice undergoing graft-versus-host reaction was used as the stimulant. The erythrocyte factor effect was also detected by 3H-thymidine uptake of bone marrow cells in liquid cultures. These results suggest that the effect of the erythrocyte factor on CSF is not restricted to CSF from a specific source nor to semi-solid agar cultures.

Granulopoietic inhibitors excreted in the urine of a patient with uterine cancer and marked leukocytosis.

An inhibitor of colony stimulating factor (CSF) was found in normal human urine and in the urine of a patient with uterine cancer and leukocytosis. The amount of inhibitor excreted in the patient's urine was inversely related to the amount of CSF excreted. Since the patient's urine contained the inhibitor in large amounts, it was used for further characterization of the inhibitor. The inhibitor was separated from CSF by DEAE-cellulose column chromatography, and precipitated by ammonium sulfate and 30-80% saturation. The result of centrifugation of the inhibitor in a NaBr solution of d = 1.21 and extraction of its solution by chloroform suggested that it is not a lipoprotein. Furthermore, it was inactivated by heating at 60 degree C. Isoelectrofocusing resolved in into two peaks of pI 6.7-8.4 (pI-7 inhibitor) and pI 4.7-5.4 (pI-5 inhibitor), both of which showed an apparent molecular weight of 80,000-90,000 upon Sephadex G-100 chromatography. Dose-response relation for CSF in the presence of the inhibitor(s) showed that the action of the inhibitor(s) was not due to specific inactivation of CSF. Both pI-05 and pI-7 inhibitor fractions showed mitogenic activity to mouse spleen cells in culture, and only slightly inhibited [3H]thymidine uptake in the PHA or LPS stimulated spleen lymphocytes. The result suggests that the granulopoietic inhibitor(s) obtained above is not a non-specifically cytotoxic substance(s).

Macrophage colony-stimulating factor purified from normal human urine. Amino-terminal sequence and amino acid composition.

A macrophage colony-stimulating factor (M-CSF) was purified to homogeneity from a large amount of normal human urine. Microanalysis of the N-terminal amino acid sequence up to residue 44 revealed only a single residue difference from that deduced by other workers from the nucleotide sequence of M-CSF cDNA clones. The amino acid composition of the present preparation suggested that the M-CSF which we purified possessed a structure fitting the sequence 1-190 of TPA30-1 cell M-CSF deduced by Wong et al. [(1987) Science 235, 1504-1508].

Radioprotection of mice by a single subcutaneous injection of heat-killed Lactobacillus casei after irradiation.

Treatment of whole-body gamma-irradiated mice with a preparation of Lactobacillus casei (LC 9018) immediately after irradiation caused a sustained increase in serum colony-stimulating activity which was followed by an enhanced repopulation of granulocyte-macrophage colony-forming cells in the femoral marrow and spleen. Numbers of blood leukocytes, erythrocytes, and platelets were increased earlier in the treated mice than in the controls, and the survival rate was elevated significantly. The radioprotective effect was dependent on the dose of LC 9018 as well as on the dose of radiation. These results demonstrate the value of LC 9018 for the treatment of myelosuppression after radiotherapy or radiation accidents.

A colony-stimulating factor produced by mouse L . P3 cells in the presence of tunicamycin or 2-deoxy-D-glucose.

L . P3 cells grown in serum-free synthetic medium produced a colony-stimulating factor (CSF: a sialoglycoprotein stimulating proliferation of granulocyte-macrophage progenitor cells). Addition of tunicamycin (2 microgram/ml) or 2-deoxy-D-glucose (10 mM) to the culture neither decreased the yield of CSF relative to the cell number grown nor induced heterogeneity of the produced CSF. However, CSF produced in the presence of tunicamycin (CSF-tm) was about 23 percent smaller in its molecular weight than normally produced CSF (CSF-normal). Similarly, the addition of 2-deoxy-D-glucose resulted in the formation of a CSF (CSF-dGlc) which was about 16 percent smaller than CSF-normal. However, both CSF-tm and CSF-dGlc seemed to have retained sialic acid residues, because they were focused respectively at pH 4.2 and pH 3.7 upon isoelectric focusing, and both were converted to a pH 5.2 species by treatment with neuraminidase. In addition, CSF-tm was significantly less heat-stable than CSF-normal, whereas CSF-dGlc was only slightly less stable. These results suggest that complete glycosylation of the factor is not necessary for its production nor for its stimulatory action on the proliferation of myeloid stem cells, but is necessary for its maximal stabilization.

Constitutive overexpression of the c-fos gene in radiation-induced granulocytic leukemia in mice.

Among various myeloid leukemias which were induced by X rays in C3H/He mice (Seki et al., Radiat. Res. 127, 146-149, 1991), the three most frequent types were analyzed for myeloperoxidase, c-myc, c-myb, and c-fos mRNAs. It was shown by in situ hybridization that all the component cells were positive for myeloperoxidase mRNA in granulocytic leukemia, whereas only half the cells were positive in myelomonocytic leukemia and none in monocytic leukemia. Granulocytic leukemia was also characterized by a persistently heightened expression of c-fos, while the other two types of leukemia showed negligibly low expression of the c-fos message. By contrast, both c-myc and c-myb were expressed to a similar extent in all three types of leukemia. When fresh granulocytic leukemia cells were transferred to culture in a medium containing 0.5% fetal calf serum, c-fos mRNA was decreased rapidly during incubation. The decay of c-fos mRNA was inhibited by cycloheximide markedly but was not changed significantly by actinomycin D. In the culture containing 10% fetal calf serum, the rate of decay of c-fos mRNA was slowed down significantly. Addition of dibutyryl cyclic AMP rapidly restored the c-fos expression and kept it elevated for at least 2 h in the cultured granulocytic leukemia cells. Phorbol ester (TPA) and calcium ionophore A23187 also caused a rapid but transient c-fos expression. A transient c-fos expression was inducible by TPA in the other two types of leukemia cells and in the granulocytic leukemia cells. The results suggest that the persistent expression of c-fos is distinguished from its transient expression and is characteristic for granulocytic leukemia cells as it is for normal mature granulocytes.

Induction of the expression of the interleukin-1 beta gene in mouse spleen by ionizing radiation.

Spleen cells freshly isolated from normal mice were irradiated with 20 Gy X rays in culture. Northern blot hybridizations revealed that expression of the interleukin-1 beta (IL-1 beta) gene was induced immediately after irradiation and was increased for 2 h thereafter. Dibutyryl cyclic AMP also caused a persistent expression of the IL-1 beta gene, although it differed from X rays in that it coincidentally induced expression of the c-fos gene, which was not induced by X rays. Activation of either protein kinase C or calmodulin also induced early expression of both IL-1 beta and c-fos. Myeloid cells collected from the spleen of mice with granulocytic leukemia were X-irradiated in culture as above. The leukemia cells responded to X rays as well as to other stimuli in the same manner as the spleen cells, except that IL-1 beta mRNA was no longer detected 30 min after irradiation while c-fos was detectable for 2 h. When the leukemia cells were irradiated twice with a 3-h interval between irradiations, the second irradiation led to prolonged expression of IL-1 beta without inducing c-fos expression. These results suggest that ionizing radiation elicits early expression of the IL-1 beta gene through a mechanism that does not involve protein kinase C or A, or the transcription factor, c-fos. Whole-body irradiation of mice with 50 Gy 137Cs gamma rays also induced IL-1 beta expression in spleen but not in bone marrow or liver, although there was a delay of several hours before it was amply expressed. Furthermore, a delay as long as 24 or 72 h was observed when the radiation dose was reduced to 8.5 or 4 Gy. The results of this in vivo study suggest that the rapidity of expression of the IL-1 beta gene is dependent on the dose of radiation, and that the cells in the body cannot respond to radiation as rapidly as cells in culture.

Radioprotective effects of serum thymic factor in mice.

Serum thymic factor (FTS) reduced mortality of mice after total-body irradiation with 7.56 Gy X rays. The radioprotective effect was achieved by daily repeated subcutaneous injections of 3-100 micrograms FTS, while doses higher than 300 micrograms/day/mouse were neither radioprotective nor toxic. Similarly, degeneration of the spleen was moderated by 3-100 micrograms FTS but not by 500 micrograms FTS in sublethally (3.78 Gy) irradiated mice. Histological examination showed that hematopoiesis was enhanced in the spleen by daily injections of 10 micrograms FTS. Spleen cells from the FTS-treated mice incorporated more [3H]thymidine in culture with or without concanavalin A. The treatment with FTS increased the production of colony-stimulating factor in the spleen as well as in peritoneal macrophage-like cells, and caused a significant increase in the number of granulocyte-macrophage colony-forming cells both in the spleen and in the femoral bone marrow. Furthermore, FTS prevented a decrease in circulating neutrophils in the sublethally irradiated mice. Prominent overshoot recovery of myelopoiesis, which occurred occasionally in sublethally irradiated mice, did not occur in the FTS-treated mice. The decrease in blood erythrocytes was also significantly reduced. These observations imply that this thymic hormone has potential as a radioprotector.

Radiosensitivity of late recurrences following radiotherapy of murine fibrosarcomas.

Radiosensitivity of late recurrent tumors which emerged after radiotherapy was investigated. Tumors observed were fibrosarcomas. Recurrences emerged in the irradiated area approximately 200 days after a 50% tumor control dose of radiation of 60Co gamma rays or mixed irradiation with fast neutrons and gamma rays. The recurrent and radiation-induced tumors were differentiated by karyotype analysis. Once transplanted into fresh mice, the recurrent tumors grew more slowly than the original tumor. Tumorigenicity of the late recurrences was lower than that of the original tumor. Radiosensitivity of the late recurrences, which was examined using methods to assess control, tumor growth delay, and colony forming assays, was significantly higher than that of the original tumor. D0 values of hypoxic tumor cells were significantly smaller in two of the three recurrences compared to the original tumor. Oxic cells, when irradiated in vitro, also showed smaller D0 values for the recurrent tumors than the original tumor. Hypoxic cell fractions were between 0 and 14% in the late recurrences and 10% in the original tumor. These results are consistent with the hypothesis that radiotherapy causes mutation of tumor cells which results in increased radiosensitivity of surviving tumor cells.

Radioprotective effects of (-)-epigallocatechin 3-O-gallate (green-tea tannin) in mice.

Long-term administration of (-)-epigallocatechin 3-O-gallate (EGCG) to mice through drinking water prevented radiation-induced increase of lipid peroxides in liver and significantly prolonged life span after lethal whole-body X-irradiation. The result indicates validity of this green-tea component as an orally active radio-protector of very low toxicity.

X-irradiation-induced emesis in Suncus murinus.

X-irradiation-induced emesis was investigated in Suncus murinus, a house musk shrew. Whole body X-irradiation caused emesis, and the calculated ED50 value that induced emesis in 50% of animals was 429 cGy. At the irradiation dose of 800 cGy all the animals vomited 10.0 +/- 2.4 times with a latency of 20.0 +/- 2.9 min. The emetogenic effect of X-irradiation was dependent on the part of the body exposed. Abdominal X-irradiation at 1000 cGy caused emesis in all animals studied, whereas the same dose to the head had no emetogenic effect. We investigated several prophylactic methods against X-irradiation-induced emesis. Surgical vagotomy completely inhibited the emesis induced by 800 cGy X-irradiation. Emesis was also prevented by the subcutaneous administration of tropisetron (ICS 205-930, a selective serotonergic 5-HT3 receptor antagonist) with an ID50 value of 29 micrograms/kg. These results suggest that (1) suncus is a useful experimental animal for the study of radiation-induced emesis and the development of prophylactic drugs, (2) serotonin plays an important role in X-irradiation-induced emesis, and (3) X-irradiation-induced emesis is very similar to that caused by cancer chemotherapeutic agents.

Timing in administration of a heat-killed Lactobacillus casei preparation for radioprotection in mice.

A single subcutaneous injection of a preparation of heat-killed Lactobacillus casei (LC 9018), given before or after irradiation, significantly increased the survival rate of mice that had received 8.5-Gy 137Cs whole-body gamma-irradiation. A similar radioprotective effect was observed when LC 9018 was administered within the period from 2 days before irradiation to 9 h after irradiation, the pre-irradiation treatment being slightly better than the post-irradiation treatment. Increases in the weight of the spleen and in the number of endogenous spleen colonies on days 8 and 12 after irradiation suggested that the radioprotective effect was based on enhanced recovery of hematopoietic tissues. The activity of macrophage colony-stimulating factor (M-CSF) in serum was rapidly increased by the treatment and was maintained at the elevated level for 13 days. At the same time, an increased level of M-CSF mRNA was detected in the livers of the treated mice. However, LC 9018 failed to save the lives of mice when administered 3 days after irradiation, although it increased serum M-CSF as effectively as noted above. The small advantage of the pre-irradiation over the post-irradiation treatment was not explained by the increases of metallothionein in the hematopoietic tissues of the treated mice.