Sister chromatid exchange in lymphocytes from patients with malignant lymphoma

Summary Sister chromatid exchange (SCE) frequencies were studied in differentially stained lymphocytes from 47 patients with malignant lymphoma. Thirteen patients were untreated when studied. The mean SCE frequency [±standard error (SE)] for these patients was 12.7±0.9 per mitosis. The mean score for 40 controls was 6.1±0.3. SCE mean scores were significantly higher in the untreated patients than in the controls (P<0.001). Seven patients were treated with radiotherapy alone. They demonstrated a mean SCE frequency (8.8±0.8) significantly lower (P<0.01) than that found in untreated patients. Eleven patients received cyclophosphamide within 4 weeks prior to study. They demonstrated a mean SCE frequency (14.3±1.3) significantly higher (P<0.05) than that found in patients who had received regimens that did not contain cyclophosphamide in the prior 4 weeks (11.1±1.3) or who had been off drugs for at least 8 weeks (10.1±0.8). Our data suggest that untreated patients with malignant lymphoma have elevated SCE frequencies, which may be further increased by certain chemotherapeutic agents.     

Effect of hyperthermia on the frequency of sister-chromatid exchanges in patients with cancer of cervix uteri

The frequencies of sister-chromatid exchanges (SCE) were studied in patients with cancer of the cervix uteri and normal controls at 37 degrees C and 40 degrees C. At 37 degrees C the mean frequency of SCE was found to be 8.26 +/- 1.91 in untreated patients with cervical cancer and 7.91 +/- 1.68 in cancer patients treated with radiotherapy; these values were significantly higher than the control value of 5.34 +/- 1.28 exchanges. Increase of the growth temperature to 40 degrees C elevated the SCE frequency to 11.95 +/- 2.12 in patients without radiotherapy treatment, 13.37 +/- 2.17 in patients with radiotherapy treatment and 7.82 +/- 1.84 in normal controls. These data indicate that there is a differential induction of SCEs by hyperthermia in the lymphocytes of control women and patients with cancer of the cervix uteri.     

Sister chromatid exchange in lymphocytes from patients with Acute lymphoblastic leukemia

Summary Sister chromatid exchange (SCE) frequencies were studied in peripheral lymphocytes from 16 patients with newly diagnosed acute lymphoblastic leukemia (ALL) prior to the initiation of chemotherapy. The mean SCE frequency ( ±SE) for these patients was 12.2±0.2 per metaphase, which was significantly higher (P(0.001) than the mean SCE score for 14 agematched controls, 7.6±0.2. Five of these patients were studied again while they were receiving maintenance therapy consisting primarily of daily 6-mercaptopurine and weekly methotrexate. Their remission SCE levels remained significantly higher than controls (P(0.005). In addition, SCE levels were studied in 7 long-term survivors of ALL. Three of these patients had been receiving continuous maintenance therapy for at least 3 years. Their mean SCE scores were significantly greater than controls (P(0.005). The other 4 patients had finished their final course of chemotherapy at least 8 months prior to the time of sampling, and their mean SCE scores were not significantly different from controls (P>0.10). These data indicate that untreated patients with ALL have increased SCE levels which remain elevated during periods of remission maintained with chemotherapy. However, longterm survivors of ALL who are in remission and off chemotherapy do not demonstrate significantly increased SCE frequencies.     

Cytogenetic studies on blood lymphocytes from patients with Schistosoma mansoni

Chromosomal aberrations and sister chromatid exchange (SCE) frequencies were studied in peripheral blood lymphocytes from 10 patients with Schistosoma mansoni prior to initiation of chemotherapy. The mean frequencies of chromatid and chromosome breaks for the patients were 1.80 and 2.30%, respectively, which were significantly higher (P less than 0.01) than the means 0.35 and 0.30%, scored for 20 healthy controls. Significant increase in the mean frequency of SCEs in the patients (9.1 +/- 0.5 SCE/cell) was noticeable when compared with the controls (6.2 +/- 0.1 SCEs/cell). Reductions in the lymphocyte divisions and replications in the patients were also observed. These results indicate that infection with S. mansoni could have in vivo mutagenic effects on human chromosomes.     

Sister-chromatid exchanges in lymphocytes from infants with Down's syndrome

Sister-chromatid exchange (SCE) frequencies were studied in blood lymphocytes from 12 patients (3 females and 9 males) with Down's syndrome (DS). The mean frequency of SCE per metaphase for the patients (both sexes) was 9.2 +/- 0.8 which was significantly higher (P less than 0.01) than the mean SCE value (5.1 +/- 0.2) scored for 16 healthy infants (8 females and 8 males). A significant increase in the mean frequency of SCE in 12 parents of infants with DS (8.7 +/- 0.9 SCE/cell) was noticeable when compared with 20 parents of normal infants (6.3 +/- 0.1 SCE/cell). Increases in cellular division with reduction in their replication were also observed in patients with DS. Treatment with mitomycin C (0.05 micrograms/ml), hycanthone (0.1 micrograms/ml) and gamma-radiation (0.1 Gy) revealed a significant (P less than 0.01) increase in frequencies of SCE in DS lymphocytes and in those of their parents as compared to controls. These data may reveal a familial hypersensitivity reaction to these agents. The results indicate a genomic instability and deranged DNA-repair mechanisms which are accentuated by exposure to mutagenic agents, the underlying causal factor for which might be genetic.     

Chromosomal aberrations in patients with primary biliary cirrhosis

Summary Chromosomal aberrations in untreated lymphocyte cultures, bleomycin (BLM)-induced aberrations and sister chromatid exchanges (SCE) in the peripheral blood lymphocytes of 11 patients suffering from primary biliary cirrhosis (PBC) and 14 matched control individuals were analysed. The lymphocytes of the PBC patients had on average a lower mitotic index (2.3) compared with controls (3.5) in the untreated cultures. The mean baseline rate of aberrations of the cultured lymphocytes of the patients was 5.3 aberrations per 100 metaphases (%); this was significantly different (P=0.0291) from that of the controls with a mean of 2.3%. In lymphocytes of the patients and controls, most of the aberrations observed took the form of gaps; there was an almost equal breakage rate in both groups (0.5% and 0.4%, respectively). The average number of mitoses with aberrations in the PBC patients studied was double that of the controls (4.9% and 2.3% respectively, P=0.0323). The mean number of the BLM-induced aberrations was 54.0% and 27.7% for the lymphocytes of the patients and controls, respectively. The mean number of the aberrant mitoses in the BLM cultures was 6 times higher than that of the untreated cultures for both groups, 25.7% and 14.6% respectively (P=0.018). The chromosomal distribution of baseline and induced aberrations was not random. The PBC patients had a mean number of 8.7 SCE per mitosis, which was significantly higher than the SCEs in the controls (6.3 SCE per mitosis; P=0.0156). The evidence suggests that the chromosomes of the lymphocytes of PBC patients may be less stable than those of the control individuals in this study.     

Sister-chromatid exchanges in lymphocytes from patients with Schistosoma hematobium

Sister-chromatid exchange (SCE) frequencies were studied in peripheral blood lymphocytes from 19 patients (13 males and 6 females) with Schistosoma hematobium, prior to the initiation of chemotherapy. The mean frequency of SCE per metaphase for the patients (both sexes) was 10.4 +/- 4.2 which was significantly higher (P less than 0.01) than the mean SCE (6.4 +/- 1.1) score for 35 healthy controls. A highly significant reduction in lymphocyte division and delay in cell-cycle progression as a result of infection were also noticed. These data indicate that infection with S. hematobium could increase SCEs in the host somatic cells.     

Paradoxical changes in SCE frequencies persistently elevated in vivo, on exposure to a mutagen in vitro

Lymphocyte cultures from 4 individuals with persistently significantly elevated frequencies of sister-chromatid exchange (SCE) were examined with no treatment, and with 2 concentrations of mitomycin C. In each of the 4 cases, the mean level of SCEs in the untreated lymphocytes exhibited a paradoxical reduction in SCE frequency when exposed to the lower (0.005 microgram/ml) of the two doses of mitomycin C. At the second higher dose of mitomycin C (0.025 microgram/ml) the mean level of SCE/cell exceeded the untreated mean. When the distributions of SCE/cell were examined it appeared that the untreated cultures had two or more populations of cells; one was in the normal SCE frequency range, while the second population was in an elevated SCE frequency range. The paradoxical reduction in SCE frequency was apparently due to elimination of, or mitotic inhibition of cells in the highest range of SCE frequency, while a small elevation in SCEs was initiated in the cells with a normal SCE frequency. Thus, mean levels of SCE/cell can be misleading. This data suggests that new exposure to the same or a different genotoxic agent might possibly result in a misleading lowering of the mean SCE frequency.     

Sister chromatid exchange in lymphocytes in myelodysplastic syndrome

Sister chromatid exchange (SCE), percentage of first, second, third mitoses, blastic transformation index and mitotic index in patients with myelodysplastic syndrome (MDS) (3 with refractory anaemia, 2 with refractory anaemia with sideroblasts, 1 with refractory anaemia with excess of blasts, 4 with refractory anaemia with excess of blasts in transformation) and in 15 healthy volunteers were estimated. Three types of lymphocytes cultures were set up: first with phytohemaglutinin (PHA), second with PHA and bromodeoxyuridine (BRdU), third with BRdU. In healthy persons the SCE frequency was negatively correlated to proliferating rate index, but in MDS such correlation was not found. The lymphocytes cell cycle duration based on percentage of mitoses was longer in MDS patients than in controls. The results of our studies show the disturbances of lymphocytes during cell cycle division resulting in higher SCE frequency and lower proliferating rate compared to controls.     

Sister chromatid exchanges in patients with precancerous and cancerous lesions of cervix uteri

Summary The frequency of sister chromatid exchanges (SCEs) was studied in leucocytes from 46 patients with cervical carcinoma, 89 precancerous lesions, and 43 age-matched control women. The frequency of SCEs was found to be 10.15 ±2.49 in cancer, 8.83±2.15 in precancerous lesions, and 7.55±2.24 in controls. The analyses of SCE data revealed a highly significant (P<0.001) increase in precancerous and cancerous lesions compared to controls. The intra-chromosomal distribution of SCEs revealed a random increase in various chromosomal groups in patients with cancer and dysplasia compared to controls. The mean SCE level among various groups of precancerous lesions according to severity of pathological condition did not show significant differences. However, 70.8% of dysplasia cases revealed SCE levels higher than the average in controls. The increased frequencies of SCEs in the majority of cancer patients and a few, precancerous lesions indicate that individuals with high SCE levels may be at a high risk of developing cancer. Thus the usefulness of SCE levels as a preclinical marker to identify the high risk group of dysplasias needs to be ascertained by follow-up studies; these are in progress.     

Frequency of sister chromatid exchanges in oncological patients during treatment with cyclophosphane

The sister chromatid exchange (SCE) level in patients with cancer of lungs before treatment did not differ from the mean number of SCE in healthy donors. In the process of a cyclophosphane treatment the SCE frequency in the patient lymphocyte culture increased with the drug doses of 4 and 5 g. Analysis of the ratio of cells in mitoses I, II and III revealed no differences in the cell cycle rate for groups of healthy donors, patients before the treatment, and treated patients.     

Increased sister-chromatid exchange rate and its regression during prolonged incubation in lymphocyte cultures from patients with multiple sclerosis

Peripheral venous blood lymphocytes from multiple sclerosis patients, cultured for 72 h in the presence of phytohemagglutinin, appeared to have a higher sister-chromatid exchange (SCE) rate than cells from matched controls. Prolongation of the incubation time to 9 days by adding interleukin-2 to the cultures, caused the cells from the MS patients to lose their increased SCE frequency, so that the mean rate no longer differed from that of the controls. The SCE rate of the controls did not change significantly on prolonged incubation.     

Sister-chromatid exchange and cell proliferation in cultured lymphocytes of passively and actively smoking restaurant personnel

Sister-chromatid exchange frequencies were measured in peripheral lymphocytes of 12 cigarette smokers, 20 passive smokers, and 14 non-smokers with no regular exposure to tobacco smoke. All active and passive smokers worked as waiters and waitresses in restaurants. The passive smokers showed neither an increased mean SCE value nor an increased number of high SCE frequency cells (HFCs) when compared to non-exposed non-smokers. The incidence of SCEs and HFCs was observed to be elevated (P less than 0.01; P less than 0.05, resp.) among the active smokers. The proliferation rate of lymphocytes in whole blood cultures from the different exposure groups was also studied. The proportion of cells in first mitosis was lower and the mean replication index (RI) higher among the smokers than among non-smoker controls. However, no significant correlation was observed between the individual mean SCE and the replication index.     

Sister chromatid exchange in cell lines from malignant lymphomas (lymphoma lines)

Summary The frequency of sister chromatid exchanges (SCEs) was studied in cells from three freshly established lymphoma lines, derived from two patients with Hodgkin's disease and one patient with non-Hodgkin lymphoma. These values were compared to SCE rates found in cells from two long-established lymphoma lines (Raji and BJAB) and to those recorded in control cell lines of normal human donors. The highest SCE levels were demonstrated in the freshly established lymphoma lines, the lowest SCE values separated the lymphoblastoid cell lines from healthy controls, and the older lymphoma lines Raji and BJAB presented rates in between. The influences of BUDR concentration and of the duration of BUDR treatment on the frequency of SCEs were tested. Furthermore, the dependence of the SCE rate on the time interval between establishment of the cell line and its SCE investigation was considered. The connection between elevated SCE rates and the neoplastic nature of lymphoma lines is discussed.     

Sister chromatid exchanges in the peripheral blood of cigarette smokers and in lung cancer patients; and the effect of chemotherapy

Summary Peripheral blood sister chromatid exchange (SCE) rates in chronic cigarette smokers and in subjects with cancer do not differ from those in healthy nonsmokers. SCE patterns were normal in 69 chronic cigarette smokers, including 62 patients with untreated lung cancer. In three chronic smokers with lung cancer, high SCE levels were related to recent intravenous chemotherapy.Presented in part at the 15th Annual Somatic Cell Genetics Conference, Norfolk, Virginia, November 10–12, 1976 (Hollander et al., 1977)     

Very low sister-chromatid exchange rate in Seventh-Day Adventists

42 Seventh-Day Adventists (SDAs) and 42 controls matched for sex, age and occupation had their sister-chromatid exchange (SCE) examined in peripheral blood lymphocytes. This was done to examine if the SCE frequency was lower in this group of people, who are known to have a decreased cancer risk compared to the general population. The average SCE/cell in 30 cells from each person was 5.54 +/- 0.07 (mean +/- standard error of the mean) for the SDAs and 8.00 +/- 0.15 for the controls, the difference being statistically significant (p less than 0.00001). No difference in SCE frequency was found between SDAs eating only an ovo-lacto-vegetarian diet and those eating some fish or meat. The mitotic index (MI) was significantly higher and the replication index (RI) was significantly lower in SDAs than in controls. No correlation was found between gamma (a statistical transformation of SCEs/cell) and MI or RI within the groups of SDAs or controls. In the pooled data there was a negative correlation of gamma and MI and a positive correlation of gamma and RI. Of the interpersonal variation in gamma 8% and 14% could be explained by MI and RI. The finding of a lower SCE frequency in a group of SDAs who have a low risk of cancer might indirectly indicate a relation between SCE and cancer and encourages further studies of SCE and diet.     

Increased frequency of sister chromatid exchanges in peripheral lymphocytes of alcoholics and cigarette smokers

Sister chromatid exchange (SCE) is a sensitive indicator of genotoxicity. In this study we investigated the effects of alcohol consumption and cigarette smoking on the frequency of SCE in cultures of peripheral lymphocytes. The rate was higher in alcoholics who smoked (10.89+/-2.46) and in smokers (positive controls) (7.64+/-1.01) than in healthy non-smokers (negative controls) (6.96+/-2.18). Statistical analysis suggested that the increases were related to alcohol consumption and cigarette smoking (p<0.05).     

Frequency of anticardiolipin, antinuclear and anti-beta2 glycoprotein I antibodies in children with epilepsy

A high prevalence of epilepsies in specific immunological diseases suggests that the immune system may play a role in the pathogenesis of epilepsy or might be associated with it. In this study the frequency of anticardiolipin antibodies (aCL), antinuclear antibodies (ANA) and anti-beta2-glycoprotein I antibodies (anti-beta2-GPI) in 40 children with epilepsy and in 38 healthy subjects was determined. Positive aCL was found in 3 patients, and anti-beta2-GPI in 1 patient. In control group they were negative. ANA antibodies were negative in both groups. Duration of epilepsy < 1 year was observed in all three patients with positive aCL. No statistically significant difference was found concerning the presence of these antibodies between patients and controls. There was no statistically significant correlation of age, sex, age at the onset of epilepsy, duration of epilepsy, type of epilepsy, seizure frequency or specific antiepileptic medications with the presence of any measured antibodies.     

Cytogenetic analyses utilizing various clastogens in two sibs with Fanconi anemia,their relatives,and control individuals

Summary Structural chromosome damage, sister chromatid exchange (SCE), and proliferation kinetics were studied on lymphocyte cultures from the peripheral blood of two sibs exhibiting signs of Fanconi anemia, their relatives, and control individuals. While the rate of spontaneous chromosome breakage was at the lower limit of that known for Fanconi anemia in our patients, a distinctly greater increase than in controls of breakage frequency could be induced by isoniazid (INH), 4-nitroquinoline-1-oxide (NQO), and diepoxybutane (DEB) in their lymphocytes. Increased aberration frequencies as compared with controls were also observed in the clastogen-exposed lymphocyte cultures of the parents of both sibs, but in some experiments (NQO, DEB 24h) only in the cells of the healthy brother. There was an increase in the breakage rate of bromodeoxyuridine (BrdU)-labeled consecutive mitoses under the action of NQO, but a decrease with INH as the test clastogen.No significantly higher SCE frequency was found throughout the study in untreated and clastogen-exposed FA lymphocytes as compared with the respective controls. Proliferation was clearly inhibited by INH and NQO as indicated by a distinct increase of the percentage of BrdU-labeled first and a drastic decrease of third metaphases. The present test clastogens were shown not only to be suitable for ensuring the diagnosis of FA in patients with a low incidence of spontaneous breakage but also for determining clastogen-sensitive heterozygotes. According to these results cross-link repair cannot be the only mechanism affected by the basic defect of Fanconi anemia.Dedicated to Professor Dr. A. Barthelmess on the occasion of his 75th birthdayThis paper contains parts of the M.D. theses of D.K., H.M., and M.N.     

Cytogenetic biomonitoring of an Italian population exposed to pesticides: chromosome aberration and sister-chromatid exchange analysis in peripheral blood lymphocytes

Chromosome aberrations (CA) and sister-chromatid exchanges (SCE) were measured in lymphocytes of (A) 32 healthy individuals working in the flower industry and exposed to pesticides, (B) 32 individuals exposed as above and hospitalized for bladder cancer, and (C) 31 controls. Compounds to which floriculturists were exposed included 18 nitro-organic herbicides and fungicides, 9 nitro-organic fungicides, 12 organophosphate and organothiophosphate insecticides, 4 hydrocarbon derivative herbicides and 5 inorganic fungicides and insecticides. 150 and 70 metaphases per individual were scored for CA and SCE, respectively. A significant increase in the incidence of CA and SCE was observed in both exposed groups. Cancer patients showed the presence of rare rearrangements (dicentrics, rings and quadriradials) that were not observed in controls and were present at a lower frequency in healthy exposed people. Hyperdiploid and polyploid metaphases were also significantly increased in the 2 exposed groups compared to controls. Stratifying for age or smoking habits, although affecting the significance of individual data, did not change the substance of the results.