The Content of ROS in Blood Lymphocytes of Healthy Individuals, Individuals Irradiated as a Result of Chernobyl Disaster and Patients with Prostate Cancer.

The ROS concentration and proliferation activity (Ki67 expression.marker) have been studied in the periphery blood lymphocytes of Moscow and Obninsk citizens, donors, Chernobyl disaster liquidators, inhabitants of the region contaminated after Chernobyl disaster (Klincy) and individuals with prostate cancer. It was shown that ROS concentration in lymphocytes of the liquidators and residents of the polluted region was lowered. But in lymphocytes of patients with tumors the ROS content was higher in comparison with the control. The cell content with Ki67 expression in lymphocytes of the individuals resided in the polluted region and tumor patients was lowered.

[The radiosensitivity change after low-dose irradiation, possible mechanisms and regularities].

This paper is a short review of literature data and results of our own investigation into the adaptive response (AR). It was aimed at the analysis of the AR induction, its formation, some mechanisms, its expansion, and universality. It is supposed that a lot of mechanisms, a high variability degree, the absence of this phenomenon in some individuals, as well as dependence on many situations make the AR induction not predictable. Perhaps AR induction is not a universal phenomenon in practice, as it was supposed earlier.

[The Changes of Properties of Blood Peripheral Lymphocytes of Donors and Patients with Prostate Gland Cancer: Reaction of Lymphocytes on Irradiation in vitro].

The oxidative status (ROS), markers activation expression (CD69), proliferation activity (Ki67), proapoptotic antigen (CD95) have been investigated on healthy donors and patients with prostatic gland cancer in human blood lymphocytes. The lymphocyte reaction in vitro on γ-irradiation at different doses (0.05-1.0 Gy) has been determined too. It was shown that in these two types of individuals the ROS content does not differ and the reaction on irradiation is not different either. Essential is the difference between the marker expression in lymphocytes of healthy donors and patients with tumour: in individuals with cancer the content of lymphocytes with CD69+ phenotype (in non active situation) and CD95+ increases, the expression of marker Ki67 decreases. The lymphocyte response to irradiation in healthy and tumour lymphocytes is distinguished. Irradiation at doses 0.05-10.0 Gy on tumour patients lymphocytes markers does not influence expression. In healthy donors' lymphocytes the expression of markers is changed considerably, the reaction depends on the marker type: expression of CD69 marker decreases (tendency); expression of Ki67 decreases too; it is unusual that the expression of CD95 changes--it decreases after irradiation at the doses of 0.05-1.0 Gy, then increases with dose. So this work shows the changes in tumour patients' blood lymphocytes in comparison with healthy donors' lymphocytes. The possible mechanisms of the observed phenomenon are discussed.

[Are the properties of peripheral blood lymphocytes of patients with prostate cancer connected with the efficiency of radiation therapy?].

The genome damage (frequency of cells with micronuclei and chromosome aberrations), concentration of reactive oxygen forms (ROS), markers of lymphocytes activation, expression of proliferation (CD69, Ki67) and proapoptotic antigen (CD95), as well as the ability to adaptive response have been investigated in blood lymphocytes of healthy donors and patients with prostate gland cancer. The influence of hormone-therapy on lymphocytes properties and connection between the parameters studied with the effectiveness of treatment, which was estimated by the level of prostate specific antigen (PSA), have been investigated. It was discovered that the genome damage to the patients with prostate gland cancer lymphocytes does not differ from control. The increase of the ROS level and decrease of radiosensitivity (irradiation of isolated lymphocytes in vitro at a dose of 1 Gy) are observed but they are insignificant. The content of the cells expressing CD69 and CD95 markers doesn't change but the expression of proliferative activity marker Ki67 in cells decreases. Radiosensitivity of lymphocytes in patients with prostate gland cancer correlates with the CD95 markers expression--a higher radio sensitivity points to their predisposition to apoptotic death. The expression of the markers studied depends on the oxidative status--a high ROS level suppresses their expression. The hormone therapy applied before radiotherapy leads to the increase in radiosensitivity and decrease in ROS. As the MN test shows, the ability to adaptive response of the lymphocytes in patients with prostate gland cancer is increased as compared with lymphocytes of healthy donors but it is insignificant; moreover, hormones do not influence the ability to the adaptive response. The high oxidative status further the formation of the adaptive response. We suppose that the discovered correlation between the initial, before treatment, frequency of lymphocytes with micronuclei and treatment effectiveness, namely, the decreased number of damaged cells associated with the treatment efficiency, is very important for the treatment prognosis. The results obtained can be very important for the experimental justification and understanding a possible use of blood lymphocytes for the additional diagnostics of prostate gland cancer and prognosis for its successful treatment.

[Cytogenetic and immunological characteristics of stimulated human peripheral blood lymphocytes are connected with cell proliferation rates].

In the current study the authors investigated the connection between the proliferation rate of stimulated hu- man peripheral blood lymphocytes with some other characteristics of the population: expression of immunological markers, spontaneous genome damage, radiosensitivity. The population's proliferation index (PI) was taken as a measure of the rate. It was calculated using the composition of a cell population, which was cyto- kinesis-blocked with a cytochalasin B. If the genotoxic action is absent, the PI does not correlate with the spontaneous frequency of cells with micronuclei or with cell radiosensitivity, but is tightly linked with immunological indexes. It has been determined that after stimulation the level of marker-positive cells (CD25, CD69 and Ki67) is closely related to PI and is greater in the populations with lower proliferation rates. Irradiation of a cell culture 48 h after stimulation at a dose of 1 Gy leads to a correlation between PI and radiosensitivity, measured directly after the irradiation and in the same time frame as the PI measured in the non-irradiated population. The irradiated population's PI is not connected with the level of marker expression.

[Individual variability of immunological markers, radiosensitivity and oxidative status in blood lymphocytes of Moscow residents].

Expression of activation (CD69) and proliferation (Ki67) markers, their connection with each other, with the oxidative status (reactive oxygen species--ROS) and with radiosensitivity (determined by micronucleus test) have been studied on stimulated blood lymphocytes from Moscow inhabitants. It was shown that the content of T-lymphocytes with the expressed CD69 and the content of T-lymphocytes with the expressed Ki67 markers correlate (r = 0.571; p = 0.0004). We can suppose that expression of the CD69 marker (24 h after PHA stimulation) is needed for the cell cycle progression, but it is not enough for the high expression of Ki67 markers 48 h after stimulation (DNA synthesis phase). It was discovered that T-lymphocytes with the CD69 marker or T-lymphocytes with the Ki67 marker are connected by the negative correlation with the frequency of irradiated cell with micronucleus (MN) r = -0.487; p = 0.010; r = -0.440; p = 0.008, respectively. So we can suppose that lymphocyte radiosensitivity decreased with the increase of expression activation and proliferation markers. It was shown that radiosensitivity determined by MN test is not connected with the oxidative status determined by the reactive oxygen species content including superoxide anion radicals. It is possible to explain by the fact that the ROS concentration has been determined in non-stimulated lymphocytes, but frequencies of cells with MN - in the stimulated cells 48 h after stimulation. Using separate analysis of individual differences by the studied parameters that were determined in the same people, it was shown that individual differences are high enough in the same cases. For example, the radiosensitivity when cells were irradiated 48 h after stimulation, ROS concentration, cell content with activation and proliferation markers. In conclusion, we can say that we failed to find important correlation between the parameters studied. However, the presence of individual differences in the marker expression, the frequency of MN cells, the oxidative status in the usual inhabitants, typical donors in Moscow, is very important.

[Changes in cellular radiosensitivity after low dose irradiation].

When the adaptive response (AR) was studied on human blood lymphocytes, a new dependence was discovered. This dependence defines the direction of the radiosensitivity change after a low dose of irradiation. Using micronucleus (MN) test with cytochalasin B the dependence between the cell reaction after low level irradiation and radiosensititvity (the effect after irradiation at the dose of 1 Gy) was observed. The negative correlation between the frequency of AR manifestation, sensibilization, intermediate links and radiosensitivity was discovered. This regularity is observed in the population of Moscow, Obninsk, Chelyabinsk region (irradiated and control) inhabitants, Chernobyl accident liquidators, Moscow children, in individuals with Hodgkin's lymphoma before and during treatment. The negative correlation is also noted by AR determination with two irradiation schemes: in one or two different cell cycle phases (G1-G1 or G1-G2). Similar links are observed using the chromosome methaphase analysis (the frequency of cells with chromosome aberrations). So, the results of the experiments conducted allow us to suppose that the connection between the cell radiosensitivity and a different type of reaction after low dose irradiation--from AR to the increase in radiosensitivity (sensibilization) is a general regularity. AR is induced by low level irradiation and high cell radiosensitivity, while sensibilization is induced by low radiosensitivity. Since AR and sensibilization can be induced not only by irradiation, but many different chemicals and physical agents, the described correlation can be observed in the case of different exposures. Cellular AR and sensibilization are integral indexes depending on many genetic and epigenetic factors, as well as on the initiation of a large number of events. However, the discovered mechanisms of interrelations are still difficult to explain.

[The disturbances of the relationship between oxidative homeostasis and the immune status of lymphocytes in liquidators of the consequences of the Chernobyl accident].

We investigated into the relations between the immune status of individuals who took part in liquidating the consequences of the Chernobyl accident (liquidators) and the level of active oxygen forms in peripheral blood lymphocytes, as well as the level of the genome damage in lymphocytes (frequency of cells with micronuclei). The results show that the immune status changes as the level of the genome damage increases: the content of some markers increases and others decreases. It has also been shown that a) active oxygen forms participate in forming some indexes of the immunological lymphocyte status and b) the exposure of liquidators to irradiation many years ago almost completely changes the characteristics of the relation between the concentration of active oxygen forms and immunological status indexes. It has been shown that there are many more immunological indexes that experienced changes in their relation with the concentration of active oxygen forms than the amount of indexes associated with the genome damage. It has been found that a) there is little difference in the concentration of active oxygen forms in donors and liquidators and b) the concentration is not associated with the level of the genome damage. Taking this into account, the authors speculate that the changes in the relation between the concentration of active oxygen forms and the immunological indexes are reflection of how irradiation influences the level of the immune status formation based on the relation between the concentration of active oxygen forms and the appearance of a marker in the immune status. The obtained results point to the new, previously unknown aspects of how the primary injuries which are the result of the low dose irradiation influence the health of irradiated individuals. The changes in relations that can be seen in liquidators in comparison with donors lead to a different set of immunological indexes as well as to different immune status, and may become the reason for the deterioration in their health. The authors suppose that the above results could be a substantial contribution to the research into the fundamental mechanisms of the human immune status formation and human health.

[Molecular-biological properties of blood lymphocytes of Hodgkin's lymphoma patients. Plausible possibility of treatment effect prognosis].

Hodgkin's lymphoma (HL) patients were investigated before and during chemical and radiation therapy. The properties of peripheral blood lymphocytes of the HL patients before treatment have been compared with healthy donors and the patients during the treatment. The genetic damage--frequency of cells with micronuclei (MN), the level of DNA single- and double-strand breaks (SSB and DSB), DNA-protein cross-links (DPC) have been studied. Biochemical and physiological parameters have been compared as well: the concentration of reactive oxygen species (ROS), the ability to the adaptive response induction. The radiosensitivity of lymphocytes in vitro exposed to the 1 Gy irradiation has also been determined (by MN test). It was shown that in Hodgkin's lymphoma patients' lymphocytes (in comparison with healthy donors) the frequency of cells with MN does not change, the level of SSBs and DSBs increases, the amount of DPC does not change, and ROS concentration (on average) significantly increases because of the part of the population that have high ROS content. The ROS concentration decreases to control level, the frequency of cells with MN increases, the level of DSBs does not change but the level of DPCs (which prevents the determination of DSB) increases in the patients during treatment. It was also discovered that lymphocyte radiosensitivity correlates with the MN cells frequency before treatment and the ROS concentration. These results make it possible to suppose that the high MN frequency and high ROS concentration in Hodgkin's lymphoma patient lymphocytes (before treatment) can serve as prognostic factors for the effectiveness of radio and chemical therapy.

[Distribution of individuals by spontaneous frequencies of lymphocytes with micronuclei. Particularity and consequences].

By micronucleus (MN) assay with cytokinetic cytochalasin B block, the mean frequency of blood lymphocytes with MN has been determined in 76 Moscow inhabitants, 35 people from Obninsk and 122 from Chelyabinsk region. In contrast to the distribution of individuals on spontaneous frequency of cells with aberrations, which was shown to be binomial (Kusnetzov et al., 1980), the distribution of individuals on the spontaneous frequency of cells with MN in all three massif can be acknowledged as log-normal (chi2 test). Distribution of individuals in the joined massifs (Moscow and Obninsk inhabitants) and in the unique massif of all inspected with great reliability must be acknowledged as log-normal (0.70 and 0.86 correspondingly), but it cannot be regarded as Poisson, binomial or normal. Taking into account that log-normal distribution of children by spontaneous frequency of lymphocytes with MN has been observed by the inspection of 473 children from different kindergartens in Moscow we can make the conclusion that log-normal is regularity inherent in this type of damage of lymphocytes genome. On the contrary the distribution of individuals on induced by irradiation in vitro lymphocytes with MN frequency in most cases must be acknowledged as normal. This distribution character points out that damage appearance in the individual (genomic instability) in a single lymphocytes increases the probability of the damage appearance in another lymphocytes. We can propose that damaged stem cells lymphocyte progenitor's exchange by information with undamaged cells--the type of the bystander effect process. It can also be supposed that transmission of damage to daughter cells occurs in the time of stem cells division.

[Molecular and cellular consequences of the Chernobyl accident].

In this paper the results of the Chernobyl accident investigation 5-10 and 24 years after are summarized. The genomic instability, adaptive response formation, genome damage and oxidative status have been investigated. The studies were performed on cells in culture, mice, children and adults living in contaminated areas and liquidators. On cells in culture after exposition in the accident zone and culturing thereafter in laboratory conditions the cell proliferative activity decrease; the late cell death, the frequency of cells with micronuclei and giant cells increasing have been observed. In the progeny of exposed cells the enhancement of radiosensitivity has been noticed. So we can suppose that in cultured cells exposition in the zone of the accident the genomic instability is induced which results in many disturbances. At the organism level in mice exposed in the Chernobyl zone the radiosensitivity increase and the decrease of endotheliocytes density in brain tissue has been observed. On the stimulated by PHA blood lymphocytes of children the increase of the frequency of cells with micronuclei more than 2 time have been noticed. In all groups investigated, the decrease of individuals with significant adaptive response was observed. In children and adults inhabitants the increase of radiosensitivity after low dose of irradiation has been noticed. 24-year after the accident it was discovered that in liquidators lymphocytes the frequency of cells with micronuclei, with chromosome type aberrations, with DNA double strand breaks have been increased; the reactive oxygen species (ROS) were decreased in comparison with the control population. We can suppose that genomic instability induced in residents of contaminated regions and liquidators long after the accident results in the genetic apparatus damage, radiosensitivity enhancement, hypoxia that represent risk factors and increase the probability of tumour and non-tumour diseases. The development of these pathological processes may happen in much more remote periods.

[Adaptive response of blood lymphocytes as a marker of hemopoiesis status in exposed persons].

An obvious correlation between the type of reaction manifested by peripheral blood lymphocytes to low dose irradiation in vitro (adaptive potential), the RBM cell composition (during the period of the major exposure), and the peripheral blood cell composition (at a late time period coincident with the studies of induced radioresistance) has been found in the Techa riverside residents in the later periods after the onset of a long-term low-dose rate radiation exposure (55-60 years later) within a range of individual red bone marrow doses from 0.01 to 1.79 Gy. The nature of these dependences observed in chronically exposed individuals differs from that revealed in the controls. It can be suggested based on the results of the study that the capacity for the adaptive response shown by peripheral blood lymphocytes donated by exposed persons in the remote period after exposure can be regarded as a biological marker of the functional state of the hemopoietic stem cell pool.

[The connection between molecular-cellular parameters and immune status of liquidators after Chernobyl accident].

The genome damage (the frequencies of cells with micronuclei (MN), chromosome aberrations, the level of DNA double-strand breaks (DSB DNA), the concentration of reactive oxygen species (ROS) and 28 immunological parameters have been studied on the blood lymphocytes of Chernobyl accident liquidators. The purpose of this article was the investigation of cytogenetic, molecular changes of blood lymphocytes of irradiated individuals 24 years after accident, examination it there are correlation between genome damage and immunological parameters. It was shown that in lymphocytes of liquidators the frequencies of cells with MN and with all type of chromosome aberrations didn't differ from the lymphocytes of nonirradiated individuals, but the frequency of chromosome aberration type was increased, the level of DSB DNA was increased too. The concentration of ROS is decreased. The percent of cytotoxic CD8(+)-T-lymphocytes, natural killer cells (CD16(+)-lymphocytes), CD3+ CD16+ CD56+ (NK-T-cells), that posses antivirus and antitumor activity--HLA-DR+, regulatory T-lymphocytes (CD4+ CD25+high) in liquidators significantly increases. The level of serum immunoglobulin (Ig A) significantly increases too. The index of immune regulation, meaning of phagocyte neutrophil (FAN) and macrophage activity decreases. In liquidators there are significant correlation between the frequencies of cells with MN and the content of regulatory T-lymphocytes (p < 0.05), between the concentrations of ROS and activated T-lymphocytes. More connection is on the tendency level (p < 0.10): the frequency of chromosome aberrations, the DSB DNA level with natural killer cells and regulatory T-lymphocytes; the frequency of cells with MN and DSB DNA and FAM. We can suppose that genomic instability induced by the liquidators of Chernobyl accident consequences 24 years ago manifests now as increased genome damage and oxidative status decrease that can result in imbalance of cells and humoral immune status, disturbancies of health.

[Molecular-cellular characteristic of blood lymphocytes in Hodgkin lymphoma].

The molecular-cellular parameters complex has been studied on the blood lymphocytes of malignant Hodgkin's lymphoma (HL) patients: the frequency of cells with micronuclei (MN) and chromosome aberrations; the level of DNA single and double strand breaks - OR and DR DNA (DNA comet assay), oxidative status--the content of reactive oxygen species (ROS) by using nonfluorescent dye that is oxygenated in the cells to fluorescent reagent and detection of fluorescence intensity after there. It was shown that the patients with LH had the increased level of DR and OR DNA, the increased frequency of cells with chromosome aberrations and the number of aberrations per cell was increased too. The concentration of ROS is increased too for the most individuals with intoxication. In the process of the chemical and radiation therapy the increase of OR DNA level, the frequency of the cell with MN has been registered. The ROS concentration correlates with the level of DNA-strand breaks. So the blood lymphocytes of HL patients before treatment differ from the lymphocytes of healthy donors. The damage of genome and the change of oxidative status have been observed that can be additive markers for the HL diagnosis, their sensitivity to the treatment and the characteristic of lymphocytes changes by this disease.

[Genomic damage, adaptive response induction in blood lymphocytes at the prostate cancer patients. Connection with the tumour radiotherapy efficiency].

On the blood lymphocytes of prostate cancer (PCa) patients before and during radiotherapy: DNA damage by DNA commet assay (DNA double strand breaks - DSB); the frequency of cells with micronuclei (MN) with cytokinetic cytochalasin block; the adaptive response induction by the additional irradiation of PHA stimulated lymphocytes in the doses of 0.05 and 1.0 Gy 24 h and 48 h after stimulation were studied. Changes of these parameters with the decreasing of prostate specific antigen (PSA) have been compared. PSA decreasing is an adequate of the radiotherapy efficiency. It was shown that in oncological patients the DSB level and the frequency of cells with MN have been increased. During radiotherapy (in 3 months) the DNA DSB level and the frequency of cells with MN is enhancing. The degree and direction change of these parameters coincide. It was discovered the significant correlations between the enhancing of DNA DSB level and the cell frequency with MN during therapy and degree of the PSA level decreasing. Then it was shown that when the cell frequency with MN before treatment is higher the radiotherapy efficiency is worse. These results can have great significance for the evaluation of the prognosis of the treatment efficiency. The investigation of lymphocytes for the adaptive response ability has shown that in the patients with the pronounced adaptive response before radiotherapy the decrease of PSA level during treatment was not significant (in mean 3.5-3.6 ng/ml); when the adaptive response is absent or the phenomenon of enhanced radiosensitivity was observed the PSA level (in the most cases) was decreased very essential (in mean 0.07 ng/ml). We can suppose that prognosis of the treatment efficiency of the prostate cancer patients with the pronounced adaptive response in blood lymphocytes will be worse.

[Adaptive response in the different mitotic cycles after irradiation].

The frequency of cells with chromosome aberrations and the number of aberrations per cell by metaphase analysis have been studied in the nonirradiated progeny of irradiated human blood lymphocytes. The DNA fragmentation (DNA double strand breaks) have simultaneously been investigated by the DNA comet assay. PHA stimulated lymphocytes have been irradiated in the adaptive dose 0.05 Gy 24 h and in the challenge dose 1 Gy 48 h after stimulation to study the adaptive response (AR). 5-bromodeoxyuridine have been added for the identification the first--the fourth mitoses. It has been discovered that the frequency of chromosome aberrations is increased is all mitotic cycles after challenge irradiation, the level of double strand breaks is increased too. The adaptive response in induced by the adaptive and challenge irradiation in the first and the second mitotic cycles (fixation 48 and 72 h after stimulation) for the most parts of individuals, but it is absent in the third and the fourth mitosis. Only chromatid aberrations are observed in the first mitosis, but chromosome aberrations--in the following mitosis. Investigation by the DNA comet assay have showed the adaptive response is noticed 48-72 h after stimulation but it is insignificant 96 h. The conclusion is that the genomic instability is observed in nonirradiated progeny irradiated lymphocytes; the adaptive response is manifested up to third mitosis and is explained by the decreasing of the number of the chromatid and chromosome aberrations and DNA fragmentation. We can suppose that double strand DNA breaks can be signaling damage for the adaptive response induction.

[The mechanisms of adaptive response. Estimation of capacity of human blood lymphocytes to radiation adaptive response using different criteria].

Blood lymphocytes of 15 healthy donors have been investigated for the ability to decrease their radiosensitivity after treatment with low dose irradiation named radioinduced adaptive response (AR). The unstable chromosome aberrations were used to evaluate the radiosensitivity change after irradiation of cells with low adaptive dose (5 cGy) and subsequent high challenge dose (1.0 Gy) in comparison with the effect of challenge irradiation only. Three indexes were used: the frequency of cells with aberrations in all analyzed cells (A), the number of chromosome aberrations per cell (B) and the number of chromosome aberrations per one aberrant cell (C). It has been discovered that all donors examined can be divided into four groups: 1--individuals which cells did not show AR by all indexes used; 2--individuals which cells showed AR by indexes A and B, but not C; 3--AR was demonstrated by indexes B and C; 4--AR was confirmed by all three indexes. Generally accepted repair model for AR formation explains only the case of donor groups 3 and 4, but can not explain the mechanism leading to the case of group 2. For understanding this mechanism, the distribution of metaphases by the number of chromosome aberrations per cell was analyzes for each donor. It was shown that the part of cells without aberrations in group 2 donors increased significantly after treatment with the adaptive and challenge irradiation in comparison with that after irradiation with challenge dose only. The conclusion is that in this case AR is formed as a result of change in the frequency 0 cell class--population shift. The analogous shift was observed in the distributions of metaphases for all donors of the group 4, but was absent in the group 3 donors. The data obtained suggest that AR of blood lymphocytes might be a result of several processes: activation of submutational genome damage repair; population shifts manifested by the change in the part of undamaged cells; and, possibly, activation of apoptotic cell death. The complex nature of AR affects each of radiosensitivity evaluation criteria to a different extent.

[The radiosensitivity change of human blood lymphocytes in different mitotic cycles after a low dose irradiation].

The adaptive response (AR) in stimulated blood lymphocytes (8 donors) have been studied by two methods: analyses of unstable chromosome aberrations in metaphases and micronuclei assay (MN) with cytochalasine cytokinetic block. The adaptive irradiation in the dose of 5 cGy have been conducted 24 h and challenge irradiation after 48 h after stimulation. For the metaphase analysis of the first and subsequent mitosis cells were incubated with BrdU and were fixed 50, 72 and 96 h after the stimulation. In the MN test cells were fixed 72 or 96 h after the stimulation and cytochalasin B was added in the cell culture 24 h before fixation. Was shown that in the cells of first mitoses fixed at 50 h after stimulation only chromatid aberrations are presented in the lymphocytes of all donors and AR in all donors was noticed; but when fixation was conducted 72 h after stimulation the chromosome type aberrations are prevailing and AR is absent, 96 h after--one donor has AR. Was discovered that in the cells of the second mitosis fixed at 72 h after stimulation the only chromosome type aberrations observed, their frequency is higher that in the lymphocytes of 1 and 3 mitosis in the same fixation time, in 7 of 8 donors there is AR registered. In the cells of 3th mitosis 72 h fixation time only 1 donor has AR, in cells of the 4th mitosis nobody have AR. By the MN assay AR in two donors is observed, in the first--the increase in radiosensitivity after adapting irradiation is noticed in the rest of the radiosensitivity is not changed. 78 percent of results coincidence by MN assay with time fixation 72 and 96 h with the results of metaphase analysis in the cells of first mitosis in the same time fixation was observed. The proposition of these data explanation is that the decrease of chromatid and chromosome aberration frequency is the one is result of different enzyme systems function and the ability to the these system induction in different cells is different. If the one is decreasing the chromatid aberrations frequency is induced in lymphocytes of most donors, the second is induced rarely only in the part of cells.

[The adaptive response of first generation offsprings irradiated parents].

In offspring's of first generation irradiated inhabitants of Techa river (fathers, mothers and both parents) the spontaneous level of damaged blood lymphocytes, sensitivity of lymphocytes to the additional acute irradiation in dose 1.0 Gy and radioinduced adaptive response after adaptive (5 cGy) and challenge (1.0 Gy) irradiation 5 h after was studied. The micronuclei test with cytochalasin B as a criteria of the effect have been used. It was shown, that descendents of irradiated parents differ from the control group. The main difference is the significant decrease of the adaptive response frequency in the progeny. In the offspring's of the irradiated fathers and mothers there is no one individuals with the adaptive response; in the offspring's of both irradiated parents the frequency of individuals with adaptive response decreases in control from 19.5% to 6.8%. The distribution of descendents according to response on adaptive irradiation differ significantly from the control distribution and from the each other. And the tendency to the radiosensitivity increase after adaptive irradiation was observed. In the whole joint group of progeny the mean spontaneous cell frequency with micronuclei decreased, but the sensitivity of lymphocytes to the additional acute irradiation doesn't differ from the control. The results of the paper permit to suppose that transgenerational genome instability in human can be determined. Earlier discovered decrease of the adaptive response frequency in the Techa river livings is observed in the offspring's of irradiated fathers, mothers and both parents.

[On the response of a cell population to low-dose irradiation].

The cell composition of a population of human blood lymphocytes was studied after irradiation at doses of 5 cGy, 1.0 Gy and 5 cGy + 1.0 Gy and the use of a cytokinesis block. The frequencies of uni-, bi- and multinucleate lymphocytes with and without micronuclei (MN) were taken into account. By the standard criterion the frequency of binucleate lymphocytes with MN among binucleate lymphocytes--the donors were characterized as follows: in with reduction of radiosensitivity after irradiation with 5 cGy + 1.0 Gy as compared to the values of radiosensitivity after irradiation with 1.0 Gy only (an adaptive response, AR); in with no change of radiosensitivity after exposure to these doses (no AR); and with an increased ofradiosensitivity after exposure to these doses (syndrome of increased radiosensitivity, IRS). It was found that upon exposure to 1.0 Gy and 5 cGy + 1.0 Gy in some donors with AR, without AR and with IRS the total numbers of damaged cells in the population and the number of binucleate cells with MN were equal. This result calls in question the involvement of the repair mechanism in the alteration of radiosensitivity of lymphocytes in these donors. It was also observed that in the same donors a simultaneous increase (or a decrease in the case of IRS) of the portion of undamaged binucleate cells in the population took place. Our results demonstrate the existence of a new, populational, mechanism involved in the alteration of radiosensitivity after exposure to the adaptive and challenge doses.