PROGNOSIS OF ACUTE LEUKEMIA DEPENDING ON THE IRON METABOLISM PARAMETERS IN CHILDREN AFTER CHORNOBYL NUCLEAR POWER PLANT ACCIDENT

OBJECTIVE

To determine the influence of iron metabolism on the prognosis of acute lymphoblastic (ALL) and (AML)myeloblastic leukemia at the different phases of chemotherapy in children after Chоrnobyl accident.

MATERIALS AND METHODS

333 children (295 - ALL, 38 - AML) were examined at the stages of chemotherapy. Thecomparison group included 93 children without leukemia. Acute leukemia variants, patients survival, relapses, thenature of disease (live child or died), iron methabolism (morphometric parameters of erythrocytes, SI, SF, STf, TS),manifestations of dyserythropoiesis, bone marrow sideroblast and patients radiation dose were taken into account.

RESULTS

In 295 patients with ALL the following variants of leukemia were established: pro-B-ALL in 23, «common»type of ALL in 224, pre-B-ALL in 29, T-ALL in 19. Thirty eight patients were diagnosed with AML (11 - M1, 19 - M2,8 - M4). Doses of radiation in patients with AL were (2.78 ± 0.10) mSv and they did not correlate with clinical andhematological parameters, disease variant. Relapse rates and shorter survival were in patients with T-ALL, pro-B-ALLand AML with SF levels > 500 ng/ml (p < 0.05). The amount of children with normochromic-normocytic anemias andmanifestations of dysplasia of erythroid lineage elements was greater in the AML than in ALL. SF content in patientswas elevated during chemotherapy and was lower than the initial one only in the remission period. Transferrin wasreliably overloaded with iron: TS (70.2 ± 2.3) % compared with the control group (32.7 ± 2.1) %. Correlationbetween TS and survival of patients was detected (rs = -0.45). Direct correlation between the number of iron granules in erythrocariocytes and SF level (rs = 0.43) was established, indicating the phenomena of ineffective erythropoiesis.

CONCLUSIONS

The negative influence of iron excess in the patients body on the hemopoiesis function, manifestations of ineffective erythropoiesis and the course of acute leukemia in children have been established. Changes inferrokinetic processes in children can be the basis of leukemоgenesis development.

Delineating the Effects of Ionizing Radiation on Erythropoietic Lineage-Implications for Radiation Biodosimetry

The overall lethality/morbidity of ionizing radiation exposure involves multiple forms of inhibitory or cytotoxic effects that may manifest in different tissues with a varying dose and time response. One of the major systemic effects leading to lethality of radiation includes its suppressive effect on hematopoiesis, which could be observed even at doses as low as 1-2 Gy, whereas effects on gastrointestinal and nervous systems appear at relatively higher doses in the same order. This article reviews the effects of radiation on the three distinct stages of erythropoiesis-formation of erythroid progenitor cells, differentiation of erythroid precursor cells, and terminal maturation. During these stepwise developmental processes, erythroid progenitor cells undergo rapid expansion to form terminally differentiated red blood cells that are continuously replenished from bone marrow into the circulating peripheral blood stream. Cellular radiation response depends upon many factors such as cell lineage, rate of proliferation, and differentiation status. Therefore, we discuss radiation-induced alterations during the progenitor, precursor, and terminal maturation stages and the implications thereof. Since biomarkers of ionizing radiation exposure in human populations are of great interest for assessing normal tissue injury as well as for biodosimetry in the event of accidental or incidental radiation exposures, we also highlight blood-based biomarkers that have potential utility for medical management.

Assessment of Erythropoiesis Status in Roach (Rutilus rutilus) of the Radioactively Contaminated Techa River

At present volumetric activity of β-emitting radionuclides in water at various locations of the Techa River ranges from 5 to 40-Bq/L; a specific activity of β-emitting radionuclides in the bottom sediments at various locations ranges 10 Ito 106 Bq/kg dry weight. A significant increase of the erythroblast content in blood as compared to that in the roach from the reference watercourse (the Miass River) was observed during spawning in the spring. Due to this fact the number of erythrocytes was equal to that in the control animals under chronic radiation exposure at the dose rates of 0.9 and 16 μGy/day, and was insufficient at the dose rate of 108 gGy/day. During summer feeding no changes in the indexes of erythropoiesis in roach were observed under chronic radiation exposure at the dose rate of 0.9 μGy/day; the number of erythrocytes in the peripheral blood declines when the dose rates are 16 and 108 μGy/day. When performing a regression analysis, we revealed a dose-rate-dependent decrease in the absolute number of erythrocytes, normocytes, polychromatocytes, dividing and non-dividing erythroid cells in the peripheral blood of roach from the Techa River and an increase of a relative number of normochromatophylic erythrocytes.

[DEMONSTRATION OF LIKELIHOOD OF THE NEGATIVE EFFECT OF PHYSICAL PROTECTION DURING TOTAL PROTON IRRADIATION OF MICE]

The experiments were performed with outbred CD-1 male mice (SPF category). Total irradiation at 1.0; 2.5 and 5.0 Gy by protons with the average energy of 170 MeV was conducted in a level medical beam of the phasotron at the Joint Institute of Nuclear Investigations. Targets were 2 points of in-depth dose distribution, i.e. beam entrance of the object, and modified Bragg peak. As a physical protector, the comb filter increases linear energy transfer (LET) of 170 MeV entrance protons from 0.49 keV/μm to 1.6 keV/μm and, according to the bone marrow test, doubles the biological effectiveness of protons when comparing radiation doses that cause 37% inhibition of blood cell formation in the bone marrow. Physical protection increases dose rate from 0.37 Gy/min for entrance protons to 0.8 Gy/min for moderated protons which more than in thrice reduces time of irradiation needed to reach an equal radiobiological effect.

Comparative analysis of the dynamics of thrombocytopoietic, granulocytopoietic, and erythropoietic systems in irradiated humans: a modeling approach

Biologically motivated mathematical models, which describe the dynamics of the thrombocytopoietic, granulocytopoietic, and erythropoietic systems in irradiated humans, are thoroughly investigated. These models are the systems of nonlinear ordinary differential equations, whose variables and constant parameters have clear biological meaning. The modeling studies reveal general regularities and peculiarities of the dynamics of the aforementioned hematopoietic lines in acutely and chronically irradiated humans. It is shown that the predictions of the models qualitatively and quantitatively agree with the respective clinical data for humans exposed to acute and chronic irradiation in wide ranges of doses and dose rates. Moreover, the "lethal" dose rate of chronic irradiation, which is evaluated in the framework of the granulocytopoiesis model, coincides with the real minimal dose rate of lethal chronic irradiation for humans. As for the thrombocytopoiesis and erythropoiesis models, the respective "lethal" dose rates of chronic irradiation are very close to the real one for humans. All this bears witness to the validity of employment of the developed models in the investigation and prediction of radiation effects on human hematopoiesis.

Time-course of micronucleated erythrocytes in response to whole-body gamma irradiation in a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber)

The time course of the formation of micronucleated polychromatic (MNPCEs) and normochromatic erythrocytes (MNNCEs) in the bone marrow of the bank vole (Clethrionomys glareolus, Schreber), a model mouse-like species, was studied using the standard micronucleus test at 0, 6, 12, 18, 24, 30, 36 and 48 hr following whole-body acute γ-irradiation at a dose of 0.5 Gy. Based on the existing literature on laboratory mice, it was suggested that such a dose will not have significant effect on erythroid cell proliferation in the bank vole and hence on the time course of the rise of micronucleated cells. In total, ∼905,000 polychromatic (PCEs) and normochromatic erythrocytes (NCEs) from 82 adult bank voles were analyzed. Although the mean frequencies of MNNCEs were too low to allow for the correct assessment of their time course, an analysis of PCEs showed an increasing rate of MNPCE appearance at 6 hr that reached a maximum at 18-24 hr after irradiation and subsequently decreased. Because the kinetics of MNPCEs reflects the process of erythropoiesis, the current results regarding the time points of appearance of radiation-induced MNPCEs provide the first information on the prolongation of one of the terminal stages of erythrocyte formation in bank vole specimens, namely the stage of maturation of PCEs from erythroblasts. Moreover, the observed time-course data, as well as the low-background frequencies of MNPCEs and characteristic level of PCEs response to radiation, showed similarities between the two model species: bank vole (this study) and laboratory mice (literature data).

[Antiradiation effects of lactoferrin]

The propose of these examination was studied antiradiation effect of lactoferrin (LF). It was determined, that subcutaneous injection LF (65 or 300 mkg/kg) guinea-pigs irradiated after 1-14 days after of total gamma-irradiation (2.5 Gr) had therapeutically effect attached to the bone marrow form of acute radiation disease (ARD). This effect was explained in increase of survive the animals with 53.8% to 92.8% and stimulation erythropoiesis, judge by number of reticulocytes and increase neutrophiles (12 days ARD) and lymphocytes (12 and 16 days ARD) by comparison with control animals. LF had no effect attached to intestinal form of acute radiation disease by mice. The injection of LF before total irradiation rats of electrons (energy 25 MeV) in doses 255 Gr decreased expression of some symptom of cerebral form of acute radiation disease: prolong time of beginning convulsive period with 5.7 hours to 14.1 hours and duration of life with 7.7 hours to 15.3 hours. LF had antioxidative activity.

Hepcidin mRNA levels in mouse liver respond to inhibition of erythropoiesis

Hepcidin, a key regulator of iron metabolism, decreases intestinal absorption of iron and its release from macrophages. Iron, anemia, hypoxia, and inflammation were reported to influence hepcidin expression. To investigate regulation of the expression of hepcidin and other iron-related genes, we manipulated erythropoietic activity in mice. Erythropoiesis was inhibited by irradiation or posttransfusion polycythemia and stimulated by phenylhydrazine administration and erythropoietin. Gene expression of hepcidin and other iron-related genes (hemojuvelin, DMT1, ferroportin, transferrin receptors, ferritin) in the liver was measured by the real-time polymerase chain reaction. Hepcidin expression increased despite severe anemia when hematopoiesis was inhibited by irradiation. Suppression of erythropoiesis by posttransfusion polycythemia or irradiation also increased hepcidin mRNA levels. Compensated hemolysis induced by repeated phenylhydrazine administration did not change hepcidin expression. The decrease caused by exogenous erythropoeitin was blocked by postirradiation bone marrow suppression. The hemolysis and anemia decrease hepcidin expression only when erythropoiesis is functional; on the other hand, if erythropoiesis is blocked, even severe anemia does not lead to a decrease of hepcidin expression, which is indeed increased. We propose that hepcidin is exclusively sensitive to iron utilization for erythropoiesis and hepatocyte iron balance, and these changes are not sensed by other genes involved in the control of iron metabolism in the liver.

Erythropoietic dynamic equilibrium in rats maintained after microwave irradiation

The aim of study was to define influence of radiofrequency microwave (RF/MW) radiation on erythropoiesis in rats. The kinetics of polychromatic erythrocytes (PCEs) and micronucleated (MN) PCEs in the bone marrow (BM) and peripheral blood (PB) of rats during the intermittent subchronic experiment was followed. Rats were exposed 2h/day, 7 days/week to RF/MW of 2.45 GHz and whole-body specific absorption rate (SAR) of 1.25+/-0.36 W/kg. Control animals were included in the study. Each exposed and control group was killed on the final day of irradiation. Acridine-orange stained BM and blood smears were examined by fluorescence microscope. PCEs were obtained by inspection of 2000 BM and 1000 PB erythrocytes/slides. BMMNs and PBMNs frequency was obtained by observation of 1000 PCEs/slides. BMPCEs were increased on day 8 and 15, and PBPCEs were elevated on days 2 and 8 (p<0.05). The BMMN frequency was increased on experimental day 15, and MNPCEs in the PB was increased on day 8 (p<0.05). Findings of BM and PBPCEs or MNPCEs declined nearly to the control values until the end of the experiment. Such findings are considered to be indicators of radiation effects on BM erythropoiesis consequently reflected in the PB. Rehabilitated dynamic haemopoietc equilibrium in rats by the end of experiment indicates possibility of activation adaptation process in rats to the selected experimental conditions of subchronic RF/MW exposure.

Recombinant human prolactin protects against irradiation-induced myelosuppression

Prolactin is a multifunctional hormone that exerts many separate functions and acts as an important connection between the endocrine and immune systems. There are increasing researches implicating the role of prolactin in hematopoiesis. Enhanced erythropoiesis in pregnant women and direct erythropoietic effects in vitro of plasma either from pregnant or lactating mice have been reported. Furthermore, regression of erythroblastic leukemia has been observed in a significant number of rats after hypophysectomy. In this study, the effects of recombinant human prolactin (rhPRL) on hematopoiesis were assessed in irradiated mice. Mice were treated with rhPRL for five consecutive days after exposure to a lethal dose or a sub-dose irradiation. Prolonged survival rate and increased erythropoiesis were observed in the irradiation-induced myelosuppressive mice. It was concluded that rhPRL might act on erythropoiesis and could be a potential candidate for the treatment of irradiation-induced myelosuppresion in clinic.

Erythropoietic changes in rats after 2.45 GHz nonthermal irradiation

The purpose of this study was to observe the erythropoietic changes in rats subchronically exposed to radiofrequency microwave (RF/MW) irradiation at nonthermal level. Adult male Wistar rats (N=40) were exposed to 2.45 GHz continuous RF/MW fields for 2 hours daily, 7 days a week, at 5-10 mW/cm2. Exposed animals were divided into four subgroups (n=10 animals in each subgroup) in order to be irradiated for 2, 8, 15 and 30 days. Animals were sacrified on the final irradiation day of each treated subgroup. Unexposed rats were used as control (N=24). Six animals were included into the each control subgroup. Bone marrow smears were examined to determine absolute counts of anuclear cells and erythropoietic precursor cells. The absolute erythrocyte count, haemoglobin and haematocrit values were observed in the peripheral blood by an automatic cell counter. The bone marrow cytogenetic analysis was accomplished by micronucleus (MN) tests. In the exposed animals erythrocyte count, haemoglobin and haematocrit were increased in peripheral blood on irradiation days 8 and 15. Concurrently, anuclear cells and erythropoietic precursor cells were significantly decreased (p < 0.05) in the bone marrow on day 15, but micronucleated cells' frequency was increased. In the applied experimental condition, RF/MW radiation might cause disturbance in red cell maturation and proliferation, and induce micronucleus formation in erythropoietic cells.

[Method of integral evaluation of alterations in the body systems due to various factors on the basis of generalized parameters]

The paper presents generalized parameters for quantitative evaluation of shifts in human health and separate body systems due to external factors based on available circumstantial data of prophylactic medical examination of different cohorts of population and professional groups. Test of the generalized logarithmic parameter proved its applicability to the quantitative evaluation of radiation damage to and recovery processes in the blood-forming system following repeated acute exposures. A significant fall in the rate of recovery of the system and increases in the number of fractions and the total absorbed dose were demonstrated.

Formation and repair of DNA double-strand breaks in gamma-irradiated K562 cells undergoing erythroid differentiation

Cellular differentiation is accompanied by gross changes in nuclear organization, metabolic pathways and gene expression characteristics. To investigate, whether the response to radiation damage is altered during cellular differentiation, we studied the formation and repair of DNA double-strand breaks in gamma-irradiated K562 erythroleukemia cells induced to differentiate by exposure to butyric acid. We applied an assay based on pulsed-field gel electrophoresis and Southern hybridization to measure break induction in several genomic restriction fragments. Pulsed-field gel electrophoresis of (14)C-labelled unrestricted DNA was used to study the rejoining of gamma-radiation-induced breaks in the whole genome. Total rejoining and joining of correct break ends in specific genomic regions was monitored by hybridization analysis of blots of unrestricted and restriction digested DNA with single-copy probes. The yields of gamma-ray-induced DNA double-strand breaks were found to decrease with differentiation by about 20%. Correct rejoining of radiation-induced breaks, as measured by the reconstitution of broken restriction fragments, was unaltered in differentiating cells compared to actively proliferating precursor cells. Total rejoining, however, appeared to be retarded in differentiating cells. The results suggest that in spite of the fundamental changes accompanying differentiation, the cellular damage response pathways are not essentially affected throughout erythroid differentiation.

Anaemia in cancer: pathophysiology and treatment

Anaemia in cancer patients is multifactorial and may occur as a either a direct effect of the cancer, as a result of the cancer treatment itself, or due to chemical factors produced by the cancer. The clinical symptoms of anaemia vary according to the individual's capacity to respond to blood loss or reduced red cell production. The haematological features in anaemic patients depend on the different types of malignant disease. Clinical and laboratory evaluation, and examination of the bone marrow can provide important diagnostic clues in many cases. Decisions are commonly made based on subjective consideration rather than on objective data. Blood transfusion involves many hazards, some of which may be reduced or avoided. Erythropoietin (EPO) treatment has been found to be effective in preventing anaemia and in reducing the need for blood transfusions, although it would be useful to identify high-risk patient subgroups who would benefit most from this expensive treatment. In advanced cancer patients the use of blood transfusion should be evaluated on an individual basis, according to the presence of distressing symptoms and life expectancy. These measures are unlikely to have an effect in irreversible and progressive bleeding states.

[The state of one of the erythropoiesis regulatory mechanisms after ionizing radiation exposure]

New quantitative criteria of erythrocytes functional state, based on automated registration of acid erythrogramme parameters, have been proposed. Enwidened analysis of adaptive processes in rats erythropoietic system after ionizing radiation exposure (gamma-rays, 60Co, in doses 0.5; 1.0 and 6.0 Gy) has shown, that existing in norm mechanism of stimulating effects of dieresis products on genesis of young red cell forms has been maintained only at exposure 0.5 Gy and stops to function at higher gamma-ray irradiation doses.

Genetic specificity of stress-induced anemia in rats

There is a genetic difference in rat hemoglobin (Hb) beta-chain structure, with alternate alleles, A and B, at a single locus. This study was designed to find out whether marrow sensitivity due to gamma exposure and experimentally induced anemia in age-matched adult rats is entirely strain specific or is a combination of both strain and Hb genotype. Eight strains of inbred and outbred rats comprising AA and BB types were examined. The data indicate that there is a relationship between marrow sensitivity and Hb genotypes in response to erythropoietic stress caused by three techniques.

Decrease of erythropoiesis in the fetal liver of X-ray irradiated pregnant mice

To accumulate fundamental knowledge about a possible relationship between severe mental retardation caused by in utero radiation exposure and impaired oxygen transport to fetal brain, the effect of X-ray irradiation on erythropoietic activity in fetal liver of C57BL/6J mice was studied in vivo and in vitro by measuring 59Fe uptake into heme and nonheme fractions of fetal liver. For the in vitro experiments, the mice were irradiated with X-rays at a dose of 189 cGy on day 9, 11, 13 or 15 of gestation. The day after irradiation, fetal livers were dissected, homogenated, and incubated with 59Fe-labeled mouse plasma. 59Fe uptake into the heme fraction of fetal liver was markedly reduced, depending both on the fetal developmental stage at the time of irradiation and the time that had elapsed since irradiation. In the in vivo experiments, pregnant mice were irradiated with X-rays at doses of 24 to 284 cGy on day 15 of gestation. The ratios of the amounts of 59Fe incorporated in the heme and nonheme fractions significantly decreased when mice were irradiated with more than 1 Gy. These results suggested that the necessary amount of oxygen may not be transferred to the fetal brain at the time required. The possible relationship between decreased fetal liver erythropoiesis and severe mental retardation is described.

[Erythron system function in adults subjected to radiation exposure as a result of the Chernobyl accident]

The morphofunctional state of hemopoiesis in patients who suffered from the Chernobyl accident was investigated. The activation of proliferative activity of erythroid progenitor cells simultaneously with a decrease in the resistance of erythrocytes and an increase in the levels of methemoglobin, HbF, and an increase in the number of HbF-containing cells in peripheral blood were detected. Main trends in the development of adaptative processes in the erythron system as a response to affect of low doses of radiation were determined on cellular and molecular levels.

Radiation-enhanced differentiation of erythroid progenitor cells and its relation to reproductive cell death

Terminally differentiated cells usually do not divide and are, thus, reproductively dead. To elucidate the significance of radiation-enhanced differentiation to reproductive cell death, murine erythroid progenitor cells were gamma-irradiated in plasma clot cultures and the development of haemoglobinized clones was studied thereafter. If irradiation occurred when the cells had resumed proliferation, the total numbers of haemoglobinized clones and, in parallel, the numbers of newly haemoglobinized clones were elevated above control levels 6-24 h after 10-30 Gy and 24-48 h after 1 Gy respectively. Thereafter, clone numbers decreased below controls. This decrease was faster with the newly haemoglobinized clones, indicating that both the accumulation of haemoglobinized clones and fast exhaustion of the pool of more primitive precursors in the cultures are due to accelerated differentiation. The haemoglobinized clones appearing after irradiation were reduced in size without indication of direct cell death. We conclude that the reproductive cell death occurring in our system is due to enhancement of differentiation. Enhancement of differentiation is expressed by omission of cell cycles normally passed through by the cell progeny before terminal differentiation is reached. Dependence of differentiation enhancement on the presence of cycling cells at the time of irradiation indicates involvement of growth of essential cytoplasmic constituents during mitotic delay as observed in other cell systems.

Effects of sulphur-containing compounds and X-rays on the mouse erythropoietic system assayed by in-vivo peripheral blood micronucleus test

PURPOSE

The protective effect of the sulphur-containing agents, MEA (cysteamine HCl), AET (2-aminoethyl-isothiouronium Br.HBr), and WR-2721 (S-2/3-aminopropylamino/ethylphosphorothioic acid) against induction of micronuclei in the erythropoietic system by X-rays was assessed.

METHODS

The mouse peripheral blood micronucleus assay was applied. The frequency of micronucleated polychromatic erythrocytes (MNPCE) in the peripheral blood of adult male Swiss mice was determined 24 h after MEA, AET, or WR-2721 treatment, at a dose of 200 mg/kg body weight, and whole-body X-ray exposure to a dose of 6 Gy.

RESULTS

After X-irradiation of mice, the number of MNPCE was distinctly increased. MEA, AET, or WR-2721 administration, 15 min prior to X-irradiation resulted in a reduction of the X-ray-induced elevation of the frequency of micronuclei. So, the radioprotection of the sulphur-containing drugs against the induction of MNPCE in the erythropoietic system by X-rays was shown.

CONCLUSION

The mouse peripheral blood micronucleus test can be used to screen potential radioprotective agents.

Erythroid progenitor (BFU-E, CFU-E) proliferation as inferred from 5'bromodeoxyuridine labeling

Survival patterns of burst-forming unit-erythroid (BFU-E) and cluster-forming unit-erythroid (CFU-E) were studied in B6D2F1 mice after 5'bromodeoxycytidine (BrdCyd) infusion and near-ultraviolet (near-UV) light treatment. Comparison of the kinetics of BrdCyd sensitization of these colony formers with the kinetics of granulocyte-monocyte colony-forming cells (GM-CFC) and colony-forming unit-spleen (CFU-S) demonstrated a similar, but distinguishable, pattern of labeling between BFU-E and CFU-S. BFU-E and CFU-S each contain a subpopulation of unlabeled cells that diminishes with a half-life of 35 to 40 hours. Subsequent comparisons of this close association of BFU-E and CFU-S in Sl/Sld mice, again, showed similar patterns of BrdCyd labeling without evidence of an unlabeled or G0 subpopulation. These results are discussed with respect to the likelihood of a precursor relationship between these two cell types.

Hematologic effects of recombinant human interleukin-6 in dogs exposed to a total-body radiation dose of 2.4 Gy

The hematologic effects of recombinant human interleukin-6 (rhIL-6) were studied in dogs exposed to a total-body irradiation (TBI) of 2.4 Gy. IL-6 was administered over a period of 14 days at a daily dose of 18 micrograms/kg by single subcutaneous injection. Treatment was started 1 day after TBI. The data obtained for the different hematologic parameters of the irradiated IL-6-treated dogs were compared with the data obtained from dogs who received TBI of 2.4 Gy and were treated with the carrier (control). No clear influence of IL-6 treatment on the pattern of recovery of lymphocytes could be detected in comparison to the irradiated control animals. The thrombocyte counts in the period from day 1 to 16 after TBI were similar for both groups of dogs, showing a sharp decrease in counts between days 6 and 12 with a stabilization thereafter at approximately 30 x 10(3)/microL. In three of the four IL-6-treated dogs, however, thrombocyte counts increased at day 18 after the beginning of treatment. This increase occurred 7 days earlier than in the controls. In two of the three dogs showing an accelerated recovery of platelet counts, however, treatment with IL-6 caused a strong decrease in the erythrocyte counts associated with a prolonged depression in reticulocyte concentration. There was no influence on the recovery of blood granulocytes. In one of the animals responding with an accelerated thrombocyte recovery, IL-6 had no adverse effect on erythropoiesis. However, IL-6 forced the recovery of blood granulocytes in the period beyond day 10 after TBI. Another animal showed no influence of IL-6 on thrombocyte recovery but a strong depressive effect on erythrocyte and reticulocyte counts. The results show that for standardized conditions of radiation-induced bone marrow damage, the pattern of response to IL-6 in different hematopoietic lineages may show considerable variations between individuals, in contrast to what has been observed in irradiated animals treated with granulocyte-macrophage or granulocyte colony-stimulating factor (GM- or G-CSF).

Pretreatment with cytosine arabinoside does not protect against the delayed effects of irradiation on thrombopoiesis and erythropoiesis

We have examined the capacity of the thrombopoietic and erythropoietic systems to respond to challenge with the cytotoxic drug 5-fluorouracil (5-FU) following sublethal doses of irradiation. Normal adult mice respond to 5-FU with a mild thrombocytopenia followed by a marked rebound thrombocytosis. One month after 2 Gy whole-body radiation, platelet counts took longer than normal to reach a nadir after 5-FU, and the rebound thrombocytosis was reduced. A normal response was seen when the interval after radiation was extended to 4 months. Increasing the radiation dose to 6.5 Gy resulted in a much smaller rebound thrombocytosis when 5-FU was given 1 month later. Extending the interval before the drug was given resulted in a normal response being regained between 4 and 7 months. Erythrocyte levels were temporarily depressed after 5-FU in all mice, and it took longer for recovery to occur if they had been irradiated. In another series of experiments, we investigated the effect of priming the mice before irradiation to see if this resulted in radioprotection. An injection of cytosine arabinoside (Ara-C) 2 days before a dose of 6.5 Gy resulted in the expected earlier recovery in platelet counts. To see if cells of the megakaryocyte lineage were protected from the delayed effects of irradiation by this treatment, mice were given 5-FU 1 month after Ara-C plus irradiation. The period of thrombocytopenia was followed by only a small rebound thrombocytosis, and platelet counts were indistinguishable from those found for mice not primed with Ara-C before irradiation. These experiments revealed a delayed effect of irradiation on the thrombopoietic and erythropoietic systems, which was long-lasting but not permanent at the doses used. The effects were not eliminated by priming mice with Ara-C before irradiation.

Evaluation of the effect of gamma-irradiation on fetal erythropoiesis in rats using blood cell volume as the index

Rat fetuses at day 14 of gestation were irradiated externally with gamma rays at doses of 0.5-8 Gy, and the effect of radiation on the transfer of the erythropoietic site with migration of stem cells from the blood islands of the yolk sac into the liver was investigated. The LD50 was about 5 Gy for 16-day-old fetuses, 2 days after irradiation. Such fetal hematological parameters as the number of blood cells in the liver and the formation rate of micronuclei in erythrocytes, also were affected by irradiation. Two types of blood cells were present in the fetal circulating blood; small blood cells originating in the fetal liver and large blood cells originating in the blood islands of the yolk sac. The number of small blood cells in the circulating blood decreased with the increase in the radiation dose; but, the number of large blood cells remained relatively constant. This suggests that external doses of irradiation of more than 1 Gy impaired the normal transfer of the hematopoietic site (stem cell migration from the blood islands of the yolk sac into the liver.

[The effect of phenol derivatives on the antimutagenic activity of dextran]

The effects of dextran + hydrazine or amino derivative of dibunol and of dextran + cystafos derivatives with different degree of modification of their molecules on the mutagenic activity of gamma irradiation were studied using the micronucleus test in polychromatophilic erythrocytes of the mouse bone marrow. The effects of these compounds on differentiation of the erythroid series has also been studied. The mutagenic activity of gamma irradiation was most markedly inhibited by the copolymer dextran and the amino derivative dibunol. The optimal structure of copolymers was 1 heterocyclic link per 3 non-oxidized links of dextran, while the increasing number of active links in the dextran molecule insignificantly enhanced its antimutagenic effect. The studied compounds effectively protected erythropoiesis.

[The morphofunctional indices of the erythrocytic link in hemopoiesis in persons constantly working in an area of intensified radioecological control]

A study of the peripheral blood indicates that persons constantly working in the zone of rigid radiation control showed a statistically valid reduction of the hemoglobin concentration, appearance of spinous and spheric erythrocyte forms, reduction of the mechanical resistance. Simultaneously 18% of males and 26% of females revealed moderate hypochromic anemia with a normal level of serum iron. The intensity of Fe-transferrin electron paramagnetic resonance was statistically reduced, that may be related to reduction of trivalent iron to bivalent and formation of a pool of free bivalent iron--a potent inductor of lipid peroxidation. Activation of oxidative processes in blood is confirmed by significant fluctuations of the blood ceruloplasmin level.

Flow-cytometric enumeration of micronucleated polychromatic erythrocytes in mouse peripheral blood

A flow-cytometric assay is described that can be used to determine the frequency and the DNA content of micronucleated polychromatic (PCE) and normochromatic (NCE) erythrocytes in mouse peripheral blood. Thiazole orange was used for discrimination between PCEs and NCEs, while Hoechst 33342 was used to detect micronucleated PCEs and NCEs. Up to 70,000 polychromatic erythrocytes can be analyzed in less than 10 min. This corresponds to 150-3,000 micronucleated polychromatic erythrocytes, 90-95% of which are true events as determined with a fluorescence microscope after sorting. Using X-rays as the inducing agent in dose-response experiments, a significant increase can be registered at doses of 0.02 Gy. It seems possible that the method will also allow the detection of clastogenic effects of other inducing agents at lower doses than previously possible.

[Trophic effect of testosterone on erythropoiesis in the mouse]

Some differences between erythropoietin biogenesis under the action of natural stimuli and that resulting from testosterone administration are commented. Evidences are presented suggesting that androgens, apart from amplifying erythropoietin production, might exert some action on the stroma as specific erythrocytic tissue. This action could be anabolic or trophic and not erythropoietin dependent, at least to some extent, its effect being applied on the quantitative erythropoietic homeostasis.

The effect of syngeneic marrow injection upon recovery in sub- and near-lethally irradiated mice

Mice were given sub-lethal (200-600 cGy) or near-lethal (800 cGy) whole body irradiation and the effect of injecting syngeneic marrow on subsequent hematopoietic recovery was studied. Marrow cell injection enhanced erythropoietic recovery after sub-lethal irradiation as reflected in hematocrit values and rate of appearance of 59Fe-labeled red cells in blood. However, this enhanced erythropoiesis was only seen in the spleen, and 59Fe uptake in marrow was reduced. When the irradiation dose was kept constant and the marrow dose increased from 10(5) to 10(6) to 10(7) cells, there was a somewhat erratic increase in spleen 59Fe and a decrease in marrow 59Fe uptake. When marrow cell number was kept constant and the dose of irradiation was increased from 200 to 400 to 600 to 800 cGy, there was an exponential increase in spleen 59Fe uptake but the marrow 59Fe uptake changed from depressed after lower doses to increased after 800 cGy. Cell injection after sub-lethal irradiation did not increase or decrease granulocytopoiesis. Injection of irradiated marrow cells also reduced marrow erythropoiesis and this was evident after both sub- and near-lethal irradiation. However, injection of irradiated cells did not increase splenic erythropoiesis. Following splenectomy, the depressed marrow erythropoiesis attending injection of viable cells was virtually eliminated but no increase was seen. These data suggest that the injection of autologous or syngeneic marrow may not be effective as a means of accelerating hematopoietic recovery after irradiation unless near-lethal or lethal dose have been received.

Iron kinetics effects of 88 millirads. Partial-versus-total body X-irradiation

Rats were irradiated with one tibia shielded (95% marrow exposure), total body exposed (TBI, 100%), and only one tibia exposed (5%), or they were sham irradiated (SI, 0%). Plasma Fe-59 clearance time (T1/2) and Fe-59 content ratio in the right and left tibia (RT/LT) were assayed to determine the erythroid activity of the overall marrow of the animals and the relative marrow activity in the exposed and shielded tibias, respectively. When a major fraction of the overall marrow was shielded or irradiated, the overall erythroid activity levels were identical to those of the SI and TBI animals, respectively. Interestingly, enhanced normoblastosis was observed in the marrow of the exposed tibia of individual animals exhibiting normal erythroid activity in 95% of the marrow. Conversely, localized marrow with normal erythroid activity was found in a shielded tibia of individual rats, demonstrating an enhanced erythroid activity in a major fraction of the total body. It was concluded that 88 mrad can alter marrow functions in a small isolated skeletal region as effectively as in the whole body, and tandem assays of the Fe-59 T1/2 and Fe-59 RT/LT can facilitate ultra-low-dose X-ray studies involved with partial body exposures.

Postirradiation recovery of haemopoiesis in Steel mutant mice

The recovery of haemopoiesis in Steel mutant mice following 1 Gy sublethal irradiation is described. Steel homozygotes (S1/S1) did not display the abortive phase of erythropoietic recovery while the secondary phase of erythropoietic recovery was more pronounced in S1/S1 than in control (+/+) animals. On the contrary, the neutrophilopoietic recovery in S1/S1 mice was defective only during the secondary phase of recovery. Steel heterozygotes (S1/+) manifested similar, albeit less pronounced, defects. In the course of studies of recovery of eosioniphils it was observed that neither wild-type nor mutant animals expressed the abortive rise. Moreover, the kinetics of recovery of eosinophils was essentially different from both erythropoietic and neutrophilopoietic recovery, and the preirradiation level was reached in both normal and mutant animals on day 60 postirradiation as opposed to 24 and 35 days for erythropoiesis and neutrophils respectively.

Effects of hormone treatment on chromosomal radiosensitivity of somatic and germ cells of Snell's dwarf mice

The X-ray induction of micronuclei and structural chromosomal aberrations was studied in bone-marrow cells of normal and dwarf (dw) mice in combination with thyroxine and/or prolactin treatment or otherwise. Hormone treatment clearly increased micronuclei induction but not chromosome breakage, suggesting that indirect effects were involved. Since no clear differences in the timing of the final stage of erythropoiesis could be found, it is likely that the indirect effects are mediated via the formation-differentiation kinetics of erythroblasts. The induction of reciprocal translocations by X-rays in stem cell spermatogonia of dwarf mice was lower than in normals and treatment with prolactin, growth hormone and/or thyroxin, did not influence the chromosomal radiosensitivity of spermatogonial stem cells.

Differential elaboration of prostaglandin E2 by cells of the hemopoietic microenvironment in response to endotoxin

Eight daily intraperitoneal injections of endotoxin (LPS) induced hematologic abnormalities in mice like those previously observed with chronic inflammation, sterile abscess, and tumor bearing. By the ninth day, anemia, leukocytosis, hypocellularity of the bone marrow, and compensatory hemopoietic hyperplasia of the spleen had occurred. The suppressed hemopoietic recovery and impaired survival of mice with these abnormalities, after receiving an ordinarily sublethal dose of total body irradiation (600 cGy T.B.), confirmed their importance to the intact mouse and suggested that splenic hyperplasia was insufficient to compensate for a total body deficit of functional hemopoietic stem cells. Atrophy of hemopoietic tissue in the marrow with hyperplasia in the spleen implicated changes in the hemopoietic microenvironment to account for the different responses to endotoxin. Prostaglandin E2 (PGE2) serves as an important mediator of the inflammatory response and profoundly affects hemopoiesis. Previous studies had shown that low concentrations of PGE2 enhanced, and high concentrations suppressed erythropoiesis in vitro; therefore, we wondered whether stromal cells from the marrow's microenvironment produced more PGE2 in response to LPS than splenic stromal cells to explain the suppression of hemopoiesis in the marrow and its enhancement in the spleen. Indeed, synthesis of PGE2 in primary short-term cultures of adherent marrow stromal cells in response to LPS proved much greater than that observed in cultures of splenic stromal cells. Extending adherence times from 3 to 24 to 48 hours did not change the relationship. We believe that the results of our studies point to a role of PGE2 in the microenvironmental modulation of hemopoiesis in mice with activation of the inflammatory response.

Role of splenic stroma in the action of bacterial lipopolysaccharides on radiation mortality: a study in mice carrying the Slj allele

Slj/+ mice display a slight macrocytic anaemia due to a defect in their haemopoietic organ stroma. They have a deficient endogenous spleen colony (CFU-end) formation following sublethal doses of gamma-radiation compared with their normal +/+ littermates, which is likely to be due to the low pre-irradiation CFU-S content of the Slj/+ spleen. CFU-S in these congenic mice do not differ in their sensitivity to gamma-irradiation or stem cell-activating factor. While injection of +/+ mice with 10 micrograms of lipopolysaccharide-W (LPS) one day prior to irradiation led to a substantial increase in their survival, the survival of Slj/+ mice was only slightly increased. Irradiation induced a similar dose-related reduction in the numbers of CFU-S in the spleen and femora of LPS-injected Slj/+ mice compared to similarly treated +/+ mice when measured directly after irradiation. At Day 9 after irradiation, injection of LPS led to a significantly higher CFU-end formation and higher numbers of CFU-S and nucleated cells in the Slj/+ spleens compared to LPS-injected +/+ mice. No such differences in the radioprotective effect of LPS were observed in the +/+ and Slj/+ mice with respect to the splenic and femoral 59Fe-incorporation and the femoral CFU-S numbers at Day 9. These data strongly suggest a contribution by immigrating CFU-S to the CFU-S numbers and endogenous colony formation in at least the Slj/+ spleen after LPS injection and subsequent sublethal irradiation. The observations also imply that the splenic organ stroma may play a mediatory role in the radioprotective action of LPS. In addition, the data represent an extreme example of a lack of correlation between animal survival and haemopoietic parameters. Caution should be taken when applying endogenous colony counts as a means of screening potential anti-radiation drugs.

Survival of erythroid burst-forming units and erythroid colony-forming units in canine bone marrow cells exposed in vitro to 1 MeV neutron radiation or X rays

Conditioned media (CM) from allogeneic stimulated cultures of light density cells (less than 1.08 g/cm3) from the peripheral blood of normal dogs were used to stimulate the growth of erythroid burst-forming units (BFU-E) in bone marrow from normal dogs. Maximum numbers of BFU-E were obtained when 5% (vol/vol) 3 X CM and 2 U/ml erythropoietin were added to plasma clot cultures of bone marrow cells. In addition, the radiation sensitivity (D0 value) was determined for CFU-E and for BFU-E in bone marrow cells exposed in vitro to 1 MeV fission neutron radiation or 250 kVp X rays. BFU-E were more sensitive than CFU-E to the lethal effects of both types of radiation. For bone marrow cells exposed to 1 MeV neutron radiation, the D0 for CFU-E was 0.27 +/- 0.01 Gy, and the D0 for BFU-E was 0.16 +/- 0.03 Gy. D0 values for CFU-E and BFU-E were, respectively, 0.61 +/- 0.05 Gy and 0.26 +/- 0.09 Gy for cells exposed to X rays. The neutron RBE values for the culture conditions described were 2.3 +/- 0.01 for CFU-E and 1.6 +/- 0.40 for BFU-E.

[Effect of electromagnetic fields of a millimeter range on the blood system of animals depending upon their initial state and the zone of irradiation]

As a result of cytological investigations it was discovered that the millimeter range microwaves being applied once during one hour stimulated erythrocytopoiesis of intact mice and induced a change of the lymphocytes number in the blood. The reaction to the microwaves depends on the location of irradiation and animal initial state, which was estimated pertinent to the red blood cells and white blood cells number in the peripheric blood. These factors are of prognostic importance. For mice with initial white and red blood cells numbers less than 12 X 10(9) l and 8 X 10(12) l the change of erythrocytopoiesis in the left thigh and thorax bone marrow took place and lymphopenia developed due to the irradiation of hind left leg. For other animals the stimulation of erythrocytopoiesis in the right thigh bone marrow and lymphocytes was registered due to microwaves irradiation of the hind right leg. The microwave effect is considered as a combination of local and general changes. On the basis of quantitative analysis the preferable mechanism of microwaves action on the whole organism level is discussed.

Changes in erythropoiesis due to radiation or chemotherapy as studied by flow cytometric determination of peripheral blood reticulocytes

Flow cytometric determination of time dependent changes of numbers of reticulocytes in peripheral blood were investigated as a parameter for changes in erythropoiesis induced by radiation- or chemotherapy. Rats irradiated or treated with drugs (such as e.g. cyclophosphamide 100 mg/kg, vincristin 0.2 mg/kg, or mitomycin C 1.0 mg/kg) showed clear changes in erythropoietic activity. Reticulocyte numbers decreased rapidly until day 3-4 after treatment; this period was followed by a gradual increase and normal control values were seen at day 8-11. Radiation effects of doses as low 0.5 Gy could be detected in such a way. Similar studies were performed with patients with ovarian tumors treated with cis-platinum, a drug that may cause non-immune haemolysis. During prolonged treatment some patients showed increasing numbers of reticulocytes, measured at the first day of each hospitalization period, whereas leucocyte and platelet counts stayed more or less constant. Increasing numbers of reticulocytes generally indicates stimulation of erythropoietic activity of the bone marrow (due to increased blood loss); in this study increasing numbers often preceeded a decrease in hemoglobin values later on. Flow cytometric analysis of reticulocytes is therefore a potentially useful tool to detect changes in erythropoiesis, and considered more sensitive for the early recognition of patients that develop anemia, than hemoglobin measurements only.

[Effect of a corpuscular polyvalent Pseudomonas aeruginosa vaccine on the proliferation and differentiation of hematopoietic stem cells and erythropoiesis]

P. aeruginosa corpuscular polyvalent vaccine stimulates hematopoiesis in sublethally stimulated mice. The stimulating effect is dose-dependent. The most effective method of immunization is the intravenous injection of the vaccine. The degree to which the stimulation of hematopoiesis is manifested varies in different strains of mice. The stimulation of hematopoiesis is not linked with an increase in the content of erythropoietin. P. aeruginosa polyvalent corpuscular vaccine and monovaccine, prepared from P. aeruginosa strain 1313 and incorporated into the polyvalent vaccine, protect lethally irradiated mice in the postradiation survival test.

Modulation of radiation-induced hemopoietic suppression by acute thrombocytopenia

Modifications of radiation-induced hemopoietic suppression by acute thrombocytopenia were evaluated. Immediately before or after exposure to sublethal irradiation, mice were given a single injection of anti-mouse platelet serum (APS), normal heterologous serum, neuraminidase (N'ase), or saline, or no further treatment was provided. Hemopoiesis was evaluated by blood cell counts, hematocrits, and incorporation of [75Se]selenomethionine into platelets. APS and N'ase induced an acute thrombocytopenia from which there was partial recovery before the platelet count started to fall from the radiation. During the second post-treatment week, both thrombocytopoiesis and erythropoiesis were greater in mice that received APS or N'ase in addition to radiation than in control irradiated mice. Differences in leukopoiesis were not apparent. Therefore, both thrombocytopoiesis and erythropoiesis appeared to be responsive to a stimulus generated by acute thrombocytopenia in sublethally irradiated mice.

Further studies on cyclic erythropoiesis in mice

When young adult female W/Wv mice are given 0.5 micro+Ci 89Sr/g body weight intravenously, their hematocrit values oscillate from nadirs of 26% to zeniths of 42% with a periodicity of 16 days [1]. The response of the W/Wv mouse to an assortment of radioactive and hematologic stresses have been examined in an effort to understand better the pathophysiology of cyclic erythropoiesis. When the dose of 89Sr is increased, the amplitude of cycling increases as nadirs are lowered, but periodicity is unchanged. When the dose of 89Sr is lowered to 0.3 microCi or less, cyclic erythropoiesis of substantial amplitude is observed only after five or six microoscillations. A single hematopoietic insult of 80 rad x-irradiation coupled with phlebotomy produces a transient form of cyclic erythropoiesis, namely, a series of dampened oscillations prior to recovery. Finally, we report that Wv/Wv mice exhibit a form of cyclic erythropoiesis in response to 0.5 microCi 89Sr/g body weight, in which the hematocrit values of successive nadirs gradually increase, and stabilize at about 100 days. 89Sr does not induce cyclic erythropoiesis in the +/+, W/+, or W/v/+ mice, the Hertwig strain of anemic mice, or in normal BDF1 mice.

[State of the erythron in rats at late periods following acute radiation injury]

During 12 months following whole-body single exposure to ionizing radiation of 6 Gy, the experimental rats did not develop anemia but exhibited appreciable morphofunctional changes in circulating erythrocytes, for instance, shortening of their half-life time and increase in a mean diameter and dry mass. In the bone marrow, the total number of erythroid elements and the index of erythronormoblasts labelled with 3H-thymidine were increased and the time of generation of these cells reduced due to shortening of the presynthetic period.

[Thymus-dependent suppression of erythroid colony formation induced by concanavalin A in the cloning of pluripotent hematopoietic stem cells of the spleen]

The injection of the polyclonal activator of T-cells--concanavalin A--to normal mice is followed by a considerable decrease both in the erythroid colony-formation at the cloning of spleen CFUs, and in the number of T-cells and their helper activity in the same spleen suspensions. The suppression of erythroid colony-formation may be passively transferred by using spleen cells from mice treated with concanavalin A and irradiated lethally. Thymectomy of adult mice prevents from suppression of erythroid colony-formation induced by concanavalin A. These results suggest that the T-cells may suppress erythroid differentiation of hemopoietic stem cells.

Regulation of human peripheral blood erythroid burst-forming unit growth by T lymphocytes and T lymphocyte subpopulations defined by OKT4 and OKT8 monoclonal antibodies

To reexamine the influence that T lymphocytes have on the regulation of human peripheral blood burst-forming unit (BFU-E) proliferation in the absence of a statistically significant number of monocytes, very low numbers (3 to 10 X 10(3)/mL) of a null cell fraction highly enriched for BFU-E were cultured alone and in the presence of 5 X 10(5) sheep erythrocyte-purified, autologous T lymphocytes in a methylcellulose culture system containing erythropoietin. T lymphocytes consistently enhanced the growth of BFU-E from the null cell fraction, as reflected in both their number and size. Irradiation of T lymphocytes prior to coculture with null cells markedly reduced this enhancement, strongly suggesting that T lymphocytes synthesize erythroid burst-promoting factors (BPA). To determine whether there were functional differences between the two major T lymphocyte populations as defined by OKT4 (T helper/inducer) and OKT8 (T suppressor/cytotoxic) murine monoclonal antibodies to stimulate the growth of BFU-E, both T cell subpopulations were isolated by negative (panning) or positive (fluorescence-activated cell sorting) selection and cocultured with null cells. No statistically significant differences emerged between unseparated, OKT4+ and OKT8+ T lymphocytes in their ability to stimulate the growth of BFU-E. Thus, these studies provide further evidence that T lymphocytes are a major population of BPA-producing cells and further that OKT4+ and OKT8+ T lymphocytes equally elaborate these factors.

[Ability of locally irradiated bone marrow to form erythroid colonies in diffusion chambers]

It was shown that mouse bone marrow locally exposed to ionizing radiation during the period of T-lymphocytes accumulation can form, int the diffusion chambers in the absence of exogenous erythropoietin, a large number of giant and small erythroid colonies.