L-asparagine requirements of human T-lymphocytes and B-lymphocytes in culture.

The characterization of two human T-lymphocyte lines revealed that they required exogenous L-asparagine for cell growth, whereas all four B-cell lines studied were L-asparagine independent. T-cells were 800-2,000 times more sensitive to Escherichia coli L-asparaginase than were B-cells. The cytotoxic effects of a high concentration of L-asparaginase on B-cells were not related to the hydrolysis of L-asparagine but were due to heat-labile and heat-resistant substances in the enzyme. The findings were consistent with reports that L-asparaginase is effective in suppressing cellular immunity and inducing remission in patients with acute lymphocytic leukemia, mainly a non-B-cell disease. Thus these cell lines provide in vitro models for the study of a nutritional approach to chemotherapy or immunotherapy.     

Differential chemotherapeutic susceptibility of human T-lymphocytes and B-lymphocytes in culture.

After previous work from this laboratory revealed that asparaginase was 800-2,000 times more inhibitory against human T-lymphocytes in culture than against B-lymphocytes, a similar further study of 13 chemotherapeutic and immunosuppressive agents was done. Cytosine arabinoside and 5-fluorouracil also had differential inhibitory activities on human T- and B-cells in culture. On the basis of the dose producing 50% inhibition of viable cell growth on day 5, cytosine arabinoside had 45-80 times more inhibitory activity against T-cells than against B-cells. In contrast to asparaginase and cytosine arabinoside, 5-fluorouracil had 10-20 times more inhibitory activity against B-cells. The rest of the chemotherapeutic and immunosupressive agents tested had minor or no differential activity. These findings indicated that T-cell response to asparaginase and cytosine arabinoside and B-cell response to 5-fluorouracil may be exploitable for the differential immunosuppressive effects presumed to be active in vivo. In addition, such differential responses may predict differential tumor cell behavior against these chemotherapeutic agents by T- and B-cell neoplasms in vivo.     

DNA repair synthesis in guineapig pancreas following exposure to nitrosomethylurethane.

NMUT, a known pancreatic carcinogen in guineapigs, alkylates pancreatic DNA and RNA, both in vivo and in vitro. Following the in vivo administration of a single maximum tolerated dose of NMUT (30 mg/kg), a significant increase in 3H-Tdr incorporation into DNA was observed in the duodenal segment of the pancreas after four days; this increase in thymidine incorporation probably represents in vivo DNA repair synthesis.The level of normal DNA synthesis was greater in the duodenal segment than elsewhere in the pancreas. In vitro exposure of pancreatic slices from the duodenal segment to 20 mM NMUT for 30 minutes resulted in a significant increase in 3H-TdR incorporation into DNA in the presence of HU, reflecting DNA repair synthesis following NMUT-induced DNA damage; normal DNA synthesis in the pancreatic slices in vitro was markedly suppressed by 10 mM HU. Studies on the kinetics of DNA repair synthesis in pancreatic slices indicated an initial increase of 3H-TdR incorporation, followed by a steady time-dependent decline. It appears that most of the DNA repair synthesis occurs within two hours after exposure to NMUT.     

Induction of DNA fragmentation and DNA repair synthesis in human and rat hepatocytes by diethylstilbestrol

The synthetic estrogen diethylstilbestrol (DES), a known human carcinogen, was examined for cytotoxicity, and the induction of DNA damage and repair in primary cultures of human and rat hepatocytes. In both species concentrations of DES ranging from 5.6 to 18 micrograms/ml constantly produced reduction of cell viability and DNA fragmentation in dose-related amounts. However, large individual quantitative differences in the sensitivity to the cytotoxic and DNA-damaging activities of DES were observed among cultures derived from the 5 human donors. DES capability of eliciting DNA-excision repair was weak but statistically significant in both human and rat hepatocytes. Taken as a whole these results contribute to support the hypothesis of a genotoxic mechanism in DES-induced carcinogenesis.     

B-lymphocytes and T-lymphocytes in three types of bovine lymphosarcoma.

Lymphoid cells of peripheral blood, lymph nodes, and thymus from clinically normal cattle, cattle infected with bovine leukemia virus (BLV), and cattle with lymphosarcoma were characterized for T- and B-cell surface markers. B-cells were detected by the erythrocyte-antibody-complement (EAC) rosette test and the surface immunoglobulin (sig) immunofluorescence assay. Peripheral blood from BLV-infected cattle had a higher than normal percentage of B-cells by both EAC rosette and sig immunofluorescence assays. Lymphoid cells from tumorous lymph nodes of cattle with the adult type of lymphosarcoma had a higher than normal percentage of sig-bearing cells, but in the same cell preparation the EAC rosette-positive cells were fewer than sig-positive cells. T-cells were detected by the erythrocyte rosette test. The percentage of T-cells by this test in lymph nodes of adult type lymphosarcoma was lower than that in normal cattle. A distinctly lower than normal percentage of lymphocytes could be characterized as either B- or T-cells in lymph nodes thymus, and peripheral blood from the calf type and thymic type of lymphosarcoma.     

Enhanced DNA repair and tolerance of DNA damage associated with resistance to cis-diammine-dichloroplatinum (II) after in vitro exposure of a human teratoma cell line to fractionated X-irradiation

In vitro exposure of a human testicular teratoma continuous cell line to fractionated X-irradiation resulted in the expression of resistance to cisplatin. In two independently-derived sublines, designated SUSA-DXR13 and SUSA-DXR10 resulting from treatment with either 13 fractions of 1.5 Gy (dose required to reduce survival by 1 log) or 10 fractions of 3 Gy (dose required to reduce survival by 2 logs) respectively, the IC50 values for cisplatin were 2- and 3.1-fold higher than that of the parental cell line. These sublines were cross-resistant to carboplatin (approximately 2-fold) but not to adriamycin and they showed unaltered radiosensitivities. The SUSA-DXR10 subline expressed some cross-resistance to mitomycin C and melphalan but none to Carmustine (BCNU). Total glutathione content was significantly reduced in both SUSA-DXR10 and SUSA-DXR13 cells, but the activities of associated enzymes, including the glutathione S-transferases, peroxidase and reductase were not modified significantly in the resistant sublines. Resistance in the SUSA-DXR10 subline was associated with significantly decreased 195mcisplatin uptake (p less than 0.01), but this was not reflected in a reduced level of drug bound to the DNA. The formation and removal of four platinum-DNA adducts were immunochemically quantitated. Immediately following drug treatment there was a higher level of total platination of the DNA in the resistant subline indicative of increased tolerance to DNA damage. After an 18 hr post treatment incubation, there was an indication of some repair capacity in this SUSA-DXR10 cell line, which was not apparent in the parental cells. Neither the parental nor the SUSA-DXR10 cell line was proficient in the repair of the major adduct Pt-GG, whereas both lines repaired the monofunctional adduct and the adduct Pt(GMP)2. SUSA-DXR10 cells were also able to repair the intrastrand adduct Pt-AG and interstrand crosslinks, unlike the repair deficient parental cells. Higher levels of interstrand crosslinks were characteristic of the SUSA-DXR10 subline. These observations therefore implicate both enhanced repair and increased tolerance of DNA damage as mechanisms of resistance to cisplatin resulting from in vitro exposure of a human teratoma cell line to fractionated X-irradiation.     

In vivo formation and repair of O6-methylguanine in human leukocyte DNA after intravenous exposure to dacarbazine.

Blood leukocyte DNA obtained from 11 Hodgkin's disease patients undergoing ABVD chemotherapy was analysed for the presence of the precarcinogenic adduct O6-methylguanine (O6-meG) at various times (1-2 h up to 49 h) after i.v. treatment with the methylating drug dacarbazine. Adduct formation was detected in all but one of the patients examined at levels ranging up to 0.45 fmol/micrograms DNA (7.2 x 10(-7) mol/mol guanine). The levels of the adduct decreased by approximately 30% over the 24 h following exposure and were usually not detectable 49 h after exposure. In five out of seven individuals examined after more than one treatment, consistent methylation responses were noted, while in the remaining two cases the responses were mixed. No correlation between the extent of adduct formation and lymphocyte levels of the repair enzyme O6-alkylguanine-DNA alkyltransferase was observed. The average extent of O6-meG formation 1 h after dacarbazine treatment was (4.3 +/- 3.1) x 10(-2) fmol/micrograms DNA per mg/kg dose [( 1.2 +/- 0.8) x 10(-3) fmol/micrograms DNA per mg/m2 dose)]. Following exposure of rats to similar doses of dacarbazine, the corresponding levels of adduct in blood leukocyte DNA were 1.1 x 10(-2) fmol/micrograms DNA per mg/kg dose (2.6 x 10(-3) fmol/micrograms DNA per mg/m2 dose).     

Occupational and in vitro exposure to styrene assessed by unscheduled DNA synthesis in resting human lymphocytes

Lymphocytes from 38 individuals occupationally exposed to styreneconcentrations in workroom air of 1 p.p.m. to 40 p.p.m. wereexamined for any genotoxic effects using unscheduled DNA synthesis(UDS) as the indicator of DNA damage. The mean level of N-acetoxy-2-acetylaminofluorene(NA-AAF) induced UDS was significantly increased (p < 0.001)for the styrene exposed group when compared to the mean levelfor the unexposed controls. There was no significant effecton u.v.-induced UDS from the in vivo styrene exposure. Lymphocytecultures exposed in in vitro to styrene concentrations up to100 µM have confirmed the UDS data collected on individualsoecupationally exposed to styrene. In addition, the in vitrostudy has also shown that the increased NA-AAF induced UDS resultingfrom styrene exposure was paralleled by a similar increase inNA-AAF binding to DNA. Taken together these results indicatethat styrene exposure does not inhibit DNA repair synthesis,but rather it predisposes lymphocytes to an increased risk forDNA damage induction from subsequent genotoxic exposures.     

Distribution of T-lymphocytes and B-lymphocytes in peripheral blood and effusions of patients with cancer.

The relative distribution of T- and B-lymphocytes in the blood and in pleural or abdominal effusions was compared among 24 patients with fluid accumulation due to metastatic cancer and 8 patients without evidence of cancer. The data obtained indicated that the mean percentage of T-lymphocytes in malignant effusions was significantly greater than that in the peripheral blood of the same patients. At the same time, the mean eprcentage of B-lymphocytes was decreased in malignant effusions when compared with peripheral blood. Neither of these differences was observed when effusions and blood of patients with nonmalignant effusions were compared. In addition, patients with both types of effusions had fewer total lymphocytes in their blood than did normal control patients, whereas those with cancer-associated effusions had an increased proportion of active T-lymphocytes in their blood.     

Aphidicolin-sensitive DNA repair synthesis in human fibroblasts damaged with bleomycin is distinct from UV-induced repair.

Human fibroblasts repair DNA damaged by bleomycin through both short-patch and long-patch pathways, mediated by an aphidicolin-resistant (beta) and aphidicolin-sensitive (delta) DNA polymerase respectively (DiGiuseppe, J.A. and Dresler, S.L. (1989) Biochemistry, 28, 9515-9520). Despite certain similarities, aphidicolin-sensitive repair synthesis induced by bleomycin can be distinguished genetically and biochemically from that elicited by UV radiation. Permeable xeroderma pigmentosum fibroblasts of complementation groups A and G, completely deficient in UV-induced repair, display aphidicolin-sensitive repair synthesis dependent upon dose of bleomycin. Furthermore, the ribonucleotide dependence of long-patch repair induced by bleomycin differs from that of UV repair with respect to substrate specificity and apparent Km for ATP. This novel ATPase activity mediates a step prior to polymerization. By contrast, short-patch repair synthesis does not require ATP. These data suggest that, in addition to short-patch repair, human cells possess two distinct long-patch excision repair pathways. We propose that these pathways represent strand-break, base and nucleotide excision repair respectively.     

Induction of DNA repair synthesis in human urothelial cells by the N-hydroxy metabolites of carcinogenic arylamines

Urinary N-hydroxy metabolites of carcinogenic arylamines were investigated for their abilities to induce unscheduled DNA synthesis (UDS) in human urothelial cell lines HCV 29, HU 1734, and HU 1752, and in a primary culture of human urothelial cells. N-Hydroxy-2-aminofluorene (CAS: 53-94-1; N-OH-AF), N-hydroxy-2-acetylaminofluorene (CAS: 53-95-2; N-OH-AAF), and the N-glucuronide of N-OH-AF induced UDS in HCV 29, HU 1734, and HU 1752. N-Hydroxy-4-aminobiphenyl (CAS: 6810-26-0; N-OH-ABP), N-hydroxy-4-acetylaminobiphenyl (CAS: 4463-22-3; N-OH-AABP), N-hydroxy-2-aminonaphthalene (CAS: 613-47-8; N-OH-AN), N-hydroxy-2-acetylaminonaphthalene (CAS: 2508-23-8; N-OH-AAN), and the N-glucuronide of N-OH-ABP induced UDS in HCV 29. However, the N-glucuronide of N-OH-AN did not. The O-glucuronide of N-OH-AAF induced UDS in HCV 29 only when beta-glucuronidase was present. Paraoxon inhibited the induction of UDS in HCV 29 by N-OH-AAF and N-acetoxy-2-acetylaminofluorene (CAS: 6098-44-8), but not by N-OH-AF. When examined in a primary culture of human urothelial cells, N-OH-AF, N-OH-AAF, N-OH-ABP, and N-OH-AABP were active, but N-OH-AN, N-OH-AAN, 2-aminonaphthalene (CAS: 91-59-8), 2-aminofluorene (CAS: 153-78-6;), and 4-aminobiphenyl (CAS: 92-67-1) were not. These results demonstrate that human urothelial cells are able to activate both acetylated and non-acetylated N-hydroxy metabolites of carcinogenic arylamines, and they suggest that O-glucuronidation may be a detoxification mechanism for N-arylacethydroxamic acids.     

Induction kinetics of mutations at two genetic loci, DNA damage and repair in CHO cells after different exposure times to N-ethyl-N-nitrosourea

Ouabain resistance (oua^r) and 6-thioguanine resistance (6-TG^r)mutation frequencies were measured in Chinese hamster ovarycells after treatment with N-ethyl-N-nitrosourea (ENU) for varyingperiods of time. Maximal mutation frequency at the Na⁺/K⁺ ATPasegene locus (oua^r mutations) was attained within 5 min of exposure,whereas the mutation frequency at the hypoxanthine guanine phosphoribosyltransferaselocus (6-TG^r mutations) continued to increase up to 60 min,following the theoretical curve for exponential decay of ENUwith time. Detection of DNA single strand breaks (ssb) by alkalineelution showed that maximal levels were at tained within 5 minof treatment with ENU. Fast repair of DNA ssb occurred earlyafter exposure (>50% repair within 10 min). Analysis of DNAethylation products by h.p.l.c. showed initially rapid removalof O²-ethylcytosine (25% in the first hour), slow removal of7-ethylguanine, 3-ethyladenine and 3-ethylguanine and no removalat all of O⁶-ethylguanine, O⁴-ethylthymine and ethylphosphotriesters.These time-course studies reveal different target gene responsesin the fixation of DNA damage into mutations.     

人类外周血来源树突状细胞的体外诱导培养

目的 探讨体外诱导培养较高纯度和成熟度的树突状细胞(DC)的方法.方法 密度梯度离心分离人类外周血单核细胞,直接贴壁法收集前体细胞,含人类血清及细胞因子rhGM-CSF和rhIL-4完全RPMI1640培养基,37 ℃、5%CO2孵育培养;第3天全量换液并添加细胞因子,第5天加入rhTNF-α促进成熟,第8天收获悬浮细胞.同时进行形态学和细胞表型分析.结果 镜下表现为典型的DC形态特征;流式分析细胞表型CD1a阳性表达从第5天的(18.69±8.73)%增加到第8天的(78.07±9.43)%,CD83表达从(14.74±4.06)%增加到(46.82±14.15)%,第5天CD80表达(9.82±4.61)%,第8天CD80表达(60.11±20.50)%;40 ml外周血约得(3.12±1.30)×106个DC.结论 该方法可以体外诱导培养出较大数量和较高纯度的成熟DC,并且培养体系成熟,操作性和可重复性强.     

Gene-specific formation and repair of DNA monoadducts and interstrand cross-links after therapeutic exposure to nitrogen mustards.

PURPOSE: To investigate the possibility of measuring the gene-specific DNA damage after therapeutic exposure to nitrogen mustards and to examine its relationship with the clinical response. EXPERIMENTAL DESIGN: The kinetics of gene-specific monoadducts and interstrand cross-link formation/repair were measured in the p53 and N-ras genes. DNA extracted from human peripheral lymphocytes following in vitro exposure to melphalan or therapeutic exposure to melphalan or cyclophosphamide was used. RESULTS: When lymphocytes were treated in vitro with biologically relevant doses of melphalan, monoadducts accumulated rapidly in both p53 and N-ras genes, reaching maximal levels within 2 h, whereas the highest interstrand cross-link levels were found within 8 h. Thereafter, the adducts were repaired with half-lives of 14.5 +/- 0.3 h (p53) or 18.8 +/- 1.5 h (N-ras) for monoadducts and 12.4 +/- 0.8 h (p53) or 14.1 +/- 2.2 h (N-ras) for interstrand cross-links. Moreover, peak levels of monoadducts in both genes were observed 2 h after treatment in peripheral leukocytes from patients with multiple myeloma treated with high-dose i.v. melphalan, supported by autologous stem cell transplantation, whereas interstrand cross-links were maximal within 8 h. Of seven patients examined, the three who showed the least levels of DNA damage did not respond to the high-dose melphalan. CONCLUSIONS: This is the first report showing that it is feasible to measure gene-specific DNA damage in a readily accessible tissue of humans exposed to bifunctional alkylating drugs and to examine, at the level of the individual patient, the relationships between the induction/repair of cytotoxic DNA damage and clinical response or long-term complications.     

DNA repair following exposure of human lymphocytes to 4-nitroquinoline-1-oxide

The carcinogen 4-nitroquinoline-1-oxide (4NQO) is known to induce unscheduled DNA synthesis when administered to a number of mammalian cells. This effect was demonstrated in human lymphocytes. The degree of unscheduled DNA synthesis was found to be correlated with time and with 4NQO concentration. 4NQO was demonstrated to inhibit DNA replication in actively dividing lymphocytes. In addition, human lymphocytes treated with the mitogen phytohemagglutinin-M (PHA-M) were allowed to incorporate bromodeoxyuridine (BUdR) into one chain of DNA in replicative synthesis. Following this, the BUdR was removed and the cells were incubated with 4NQO and tritiated thymidine. DNA isolated from these cells was fractionated by cesium chloride gradient centrifugation into a BUdR-containing fraction of replicated DNA and a light fraction of DNA which had not yet replicated when incubated with BUdR. ³H-thymidine was found in the heavy fraction of DNA from 4NQO-treated cells which contained no newly replicated DNA. It was concluded that this represented repair synthesis.     

Breakage of human cell DNA after exposure to 3-methylcholanthrene-11,12-oxide.

Damage to and repair of DNA isolated from human neonatal and fetal skin cells were measured by alkaline sucrose gradient analysis. 3-Methylcholanthrene did not induce single-strand breaks in DNA of the cells in culture, whereas the 11,12-oxide of 3-methylcholanthrene was very effective in this regard. The cis-1,2-dihydroxy, trans-11,12-dihydroxy, and cis-11,12-dihydroxy derivatives of 3-methylcholanthrene exerted little effect. The breaks in DNA caused by 3-methylcholanthrene oxide occurred during a 60-min incubation period and were repaired during the following 60 min. Methylmethane sulfonate also induced breaks in the DNA within 60 min.     

DNA repair synthesis in rat retinal ganglion cells treated with chemical carcinogens or ultraviolet light in vitro, with special reference to aging and repair level.

A system in which the retinal tissues of noninbred Wistar rats were used in combination with autoradiography was developed for measurement of DNA repair synthesis in ganglion cells of the central nervous system. Retinal tissues in short-term organ culture were treated with various carcinogens plus tritiated thymidine ([methyl-3H]dThd) or were irradiated with UV light and then treated with [methyl-3H]dThd. Preliminary study with retinal tissues from rats at various ages revealed no age-associated changes in the levels of unscheduled DNA synthesis in ganglion cells.     

Phenotyping of human tumor-infiltrating lymphocytes before and after exposure to different in vitro stimulation conditions.

Tumor-infiltrating lymphocytes (TiL) and autologous peripheral blood lymphocytes (PBL), mainly from breast and kidney tumor patients were cultivated with high- and low-dose rIL-2 under addition of autologous tumor cells or nonmalignant epithelial cells. Tumor cells added to TIL-cultures induced an additional proliferative response. Before cultivation, CD8+ and CD25+ lymphocytes were more frequent in TIL when compared to PBL, while CD16+, CD19+ and CD56+ cells were rare. After culture, lymphocytes of both origins showed an increase of CD2+, CD25+, CD56+ and HLA-DR+ cells and a relative decrease of CD3+ cells. The CD4+/CD8+ ratios and a number of CD56+ cells were rIL-2 dose dependent.     

Induction of DNA repair synthesis by ultraviolet radiation and methylmethanesulphonate in cultured mouse lymphocytes

The induction of DNA repair synthesis by UV-radiation and methyl-methanesulphonate (MMS) was studied in mouse lymphocytes and leukemic cells by means of autoradiography and scintillation counting, after labelling in vitro with tritiated thymidine ([3H]dThd). Repair stimulation was detected by both procedures in LSTRA and YC8 leukemic cell lines as well as in primary fibroblasts of BALB/c and BALB/Mo mice. No stimulation was observed in primary cultures of lymphocytes from the spleen, thymus and lymph-nodes of the same mice. In primary lymphocytes neither stimulation with concanavalin A (Con A) nor pre-incubation with 5-bromodeoxyuridine (BUdR) were effective in making evident DNA repair. The data put into question the reliability of the repair test for the prediction of carcinogenic potential of chemicals.