UVB-irradiated T-cells undergoing apoptosis lose L-selectin by metalloprotease-mediated shedding

Abstract. Purpose : L-selectin (CD62L) is a prerequisite for leucocyte adhesion to endothelial cells of blood vessels and consequently for transmigration. Its expression on the cell surface therefore regulates the ability of lymphocytes to enter lymph nodes, to re-enter blood vessels or to invade tissues at sites of inflammation. The aim of this study was to determine the expression of CD62L on apoptotic lymphocytes after UVB irradiation. Materials and methods : Peripheral blood mononuclear cells (PBMC) were isolated from peripheral blood of normal healthy volunteers. Cells were stimulated with phorbol myristate acetate (PMA) and ionomycin for activation. Apoptosis in peripheral T-cells and Jurkat cells was induced by irradiation with UVB (120 mJ/cm2). In addition, T-cells or Jurkat cells were cultured for the indicated time with anti-Fas antibody CH11. The CH11-induced apoptosis was inhibited by the pan-caspase inhibitor zVAD-fmk. For detection of apoptosis, cells were analysed by cytofluorometry for morphological changes typical for apoptosis. The reliability of the apoptotic cell gate was confirmed by staining with FITClabelled annexin-V in the presence of propidium iodide (PI). For FACS analysis of CD62L expression on the cell-surface immunofluorescence was performed using FITC-conjugated anti-CD62L and PE-conjugated anti-CD3 antibodies. Soluble CD62L (sCD62L) in the cell supernatants was measured by standard ELISA technique. Assays were performed in the presence and absence of metalloprotease inhibitor KB8301. Results : PBMC from healthy volunteers undergoing apoptosis following UVB irradiation selectively shed CD62L, whereas the expression of the lineage-specific marker CD3 showed only minor changes. Shedding was blocked by the hydroxamic acid-based metalloprotease inhibitor KB8301. When Jurkat cells were treated with the caspase inhibitor zVAD-fmk, anti-CD95 antibodies did not induce apoptosis, and the expression of CD62L remained unaltered. Conclusion : UVB or ionizing radiation induce apoptosis in lymphocytes. The loss of CD62L is associated with apoptosis and will influence lymphocyte tra Ýcking and, by excluding them from CD62L-mediated adhesion and tissue invasion, might contribute to the regulation of inflammation.     

The effect of the ratio of CD4+ to CD8+ T-cells on radiation-induced apoptosis in human lymphocyte subpopulations

PURPOSE: Apoptosis occurs spontaneously in cultured human peripheral blood lymphocytes but is enhanced by exposure to ionizing radiation. Subpopulations of lymphocytes are known to have varying radiosensitivities to radiation-induced apoptosis. The purpose of this study was to examine the radiation-induced apoptotic response of CD4(+) and CD8(+) T-cells incubated as a complete lymphocyte population. MATERIALS AND METHODS: Using a four-colour flow-cytometry method, which measures annexin-V binding to phosphatidyl serine and propidium iodide, spontaneous and radiation-induced apoptosis was measured in the total lymphocyte fraction and in CD4(+) and CD8(+) T-cell subpopulations. RESULTS: It was found that CD8(+) T-cells were more sensitive to radiation-induced apoptosis than CD4(+) T-cells at doses up to 2 Gy. The yield of radiation-induced apoptosis in the total lymphocyte fraction decreased with increasing ratios of CD4(+) to CD8(+) T-cells (CD4/CD8 ratio). By manipulating the CD4/CD8 ratio within lymphocyte cultures, it was found that the CD4/CD8 ratio had a dramatic effect on the yield of spontaneous apoptosis of total lymphocytes fraction and CD4(+) T-cells but not CD8(+) T-cells. CONCLUSION: The CD4/CD8 ratio affects the apoptotic response of human lymphocytes and CD4(+) T-cells.     

The effect of the ratio of CD4 + to CD8 + T-cells on radiation-induced apoptosis in human lymphocyte subpopulations

Purpose: Apoptosis occurs spontaneously in cultured human peripheral blood lymphocytes but is enhanced by exposure to ionizing radiation. Subpopulations of lymphocytes are known to have varying radiosensitivities to radiation-induced apoptosis. The purpose of this study was to examine the radiation-induced apoptotic response of CD4 + and CD8 + T-cells incubated as a complete lymphocyte population. Materials and Methods: Using a four-colour flow-cytometry method, which measures annexin-V binding to phosphatidyl serine and propidium iodide, spontaneous and radiation-induced apoptosis was measured in the total lymphocyte fraction and in CD4 + and CD8 + T-cell subpopulations. Results: It was found that CD8 + T-cells were more sensitive to radiation-induced apoptosis than CD4 + T-cells at doses up to 2 Gy. The yield of radiation-induced apoptosis in the total lymphocyte fraction decreased with increasing ratios of CD4 + to CD8 + T-cells (CD4/CD8 ratio). By manipulating the CD4/CD8 ratio within lymphocyte cultures, it was found that the CD4/CD8 ratio had a dramatic effect on the yield of spontaneous apoptosis of total lymphocytes fraction and CD4 + T-cells but not CD8 + T-cells. Conclusion: The CD4/CD8 ratio affects the apoptotic response of human lymphocytes and CD4 + T-cells.     

HLA-G~+调节性T细胞在肾移植受者外周血中的比例及其功能研究

目的 确定人类白细胞抗原-G(HLA-G)区别于CD4~+ CD25~+ FoxP3~+ 调节性T细胞的细胞表型特征,观察HLA-G~+ T细胞在混合淋巴细胞培养中的免疫调节作用及其在移植免疫调节中的活性和意义.方法采用流式细胞术检测肾移植受者外周血CD4~+ HLA-G~+ GD8~+ HLA-G~+ T淋巴细胞的含量,分选HLA-G~+ T淋巴细胞,分析细胞表型,采用RT-PCR检测调节性T细胞的特异性标志FoxP3在HLA-G~+ T淋巴细胞的表达情况,以淋巴细胞分离液分离的PBMC、CD4~+ CD25~(high)、CD4~+ CD25~-细胞作为对照.取5对活体肾移植供受者的淋巴细胞进行混合培养,分别加入流式细胞术分选纯化后的HLA-G~+ 、HLA-G~- T淋巴细胞,对照组只加入供、受者淋巴细胞,MTT法观察细胞增殖和抑制情况.结果 肾移植受者外周血CD4~+ HLA-G~+ 、CD8~+HLA-G~+ T淋巴细胞表达率分别为1.95%±0.34%、3.13%±0.56%.流式细胞术分选HLA-G~+ T淋巴细胞后纯度可达55.0%～75.1%.RT-PCR 结果证明上述细胞CD25、FoxP3均为阴性表达.与HLA-G~- 组、对照组比较,混合淋巴培养3d后HLA-G~+ 组细胞增殖率明显受到抑制(P<0.05).结论 在肾移植受者外周血中存在CD4~+ HLA-G~+ 、CD8~+HLA-G~+ T淋巴细胞,这类细胞不同于CD4~+ CD25~+ FoxP3~+调节性T细胞,它们不表达CD25和FoxP3而表达免疫耐受分子HLA-G,在混合淋巴培养体系中,能显著抑制反应性细胞增殖,具有免疫调节功能.     

UV or X-Irradiation Increases the Cytoplasmic Accumulation of Rhodamine 123 in Various Cancer Cell Lines

PURPOSE: Previous studies indicated that ATP-binding cassette (ABC) membrane transporters protect against UV-induced apoptosis. We investigated the effect of UVB and X-ray irradiation on the export function of these ABC transporters in primary lymphocytes and various cancer cell lines. MATERIAL AND METHODS: We used rhodamine accumulation assays in various human malignant cell lines and peripheral blood lymphocytes (PBL). Cells were irradiated with up to 960 mJ/cm2 and up to 50 Gy of UVB and X-ray, respectively. RESULTS: We demonstrated that UVB as well as X-ray irradiation inhibit the export function of the ABC transporters in a dose-dependent fashion. For PBL, this effect did not correlate with an apoptotic phenotype. In the case of the tumor cell lines, even though the irradiation-induced inhibition of membrane transporters was accompanied by phosphatidylserine exposure, only a minority of cells had lost their mitochondrial membrane potential during the observation period. Furthermore, we demonstrated that the inhibition of membrane transporters is not a general feature of apoptosis. CONCLUSION: Irradiation inhibits the export function of ABC transporters. Although some of the irradiated cells undergo apoptosis following irradiation, the inhibition is an unique feature accompanying irradiation and not a general hallmark of apoptotic cell death. The inhibition of drug export by irradiation may offer new potential for reverting multidrug resistance of cancer cells.     

Beta-irradiation used for systemic radioimmunotherapy induces apoptosis and activates apoptosis pathways in leukaemia cells

Beta-irradiation used for systemic radioimmunotherapy (RIT) is a promising treatment approach for high-risk leukaemia and lymphoma. In bone marrow-selective radioimmunotherapy, beta-irradiation is applied using iodine-131, yttrium-90 or rhenium-188 labelled radioimmunoconjugates. However, the mechanisms by which beta-irradiation induces cell death are not understood at the molecular level. Here, we report that beta-irradiation induced apoptosis and activated apoptosis pathways in leukaemia cells depending on doses, time points and dose rates. After beta-irradiation, upregulation of CD95 ligand and CD95 receptor was detected and activation of caspases resulting in apoptosis was found. These effects were completely blocked by the broad-range caspase inhibitor zVAD-fmk. In addition, irradiation-mediated mitochondrial damage resulted in perturbation of mitochondrial membrane potential, caspase-9 activation and cytochrome c release. Bax, a death-promoting protein, was upregulated and Bcl-x_L, a death-inhibiting protein, was downregulated. We also found higher apoptosis rates and earlier activation of apoptosis pathways after gamma-irradiation in comparison to beta-irradiation at the same dose rate. Furthermore, irradiation-resistant cells were cross-resistant to CD95 and CD95-resistant cells were cross-resistant to irradiation, indicating that CD95 and irradiation used, at least in part, identical effector pathways. These findings demonstrate that beta-irradiation induces apoptosis and activates apoptosis pathways in leukaemia cells using both mitochondrial and death receptor pathways. Understanding the timing, sequence and molecular pathways of beta-irradiation-mediated apoptosis may allow rational adjustment of chemo- and radiotherapeutic strategies.     

Increased and decreased expression of CD69 and CD23, respectively, in gravity-stressed lymphocytes

BACKGROUND: Recent studies have shown that gravity-changing stress modulates expression levels of cell surface molecules on human lymphocytes. However, previous in vitro microgravity studies have been performed with lymphocytes treated with mitogenic agents. HYPOTHESIS: The aim of the study was to test if exposure of cells to gravity-changing stress alone alters the expression levels of cell surface molecules. Specifically, we examined whether the expression of activation markers is altered after exposure of lymphocytes to combinations of microgravity and hypergravity. METHODS: We used free-fall in parabolic flight for human subjects and a drop-shaft to expose peripheral blood mononuclear cells (PBMC) to gravity-changing stress. After such exposure, PBMC were isolated, and expression levels of CD69, CD23 and CD38 were estimated using three-color flow cytometry. RESULTS: Increased percentages of CD69-positive cells were observed with PBMC from 3 of 4 volunteers who undertook 10 parabolic flights. Exposure of blood to gravity-changing stress in the drop-shaft increased both ratios of CD69-positive cells and levels of CD69 expression on T and B cells. In contrast, the percentages of CD23-positive B cells was decreased. However, gravity-changing stress was not always followed by significant alteration in CD38 expression. CONCLUSIONS: Our findings suggest that CD69 and CD23 might be useful markers that are up- and down-regulated, respectively, after exposure of lymphocytes to gravity-changing stress.     

Studies on radiation-induced apoptosis in G0 human lymphocytes

PURPOSE: To determine the relationships between the frequencies of radiation-induced chromosomal alterations and the extent of apoptosis in G0 human lymphocytes. MATERIAL AND METHODS: G0 human peripheral blood lymphocytes (HPBL) were X or gamma-irradiated, in the presence or absence of the repair inhibitor cytosine arabinoside (Ara-C). Directly after irradiation, a part of the lymphocytes were stimulated to grow while the rest were stimulated 48 h after irradiation. These lymphocyte cultures were analysed for induction of chromosomal aberrations. A subset of lymphocytes was kept in G0 and analysed for cell viability, apoptosis and p53 expression. RESULTS: The fraction of cells bearing dicentrics was reduced in lymphocytes stimulated to grow 48 h post irradiation as compared to lymphocytes stimulated immediately after irradiation. The decrease in the frequency of dicentrics correlated with the increase in the number of apoptotic cells. The operative apoptotic pathway in irradiated Go lymphocytes was dependent on the expression of p53. CONCLUSIONS: The radiation-induced apoptotic response of G0 lymphocytes is p53 dependent and increases with the time they are held in G0. When mitogen was added 48 h after irradiation, cells with dicentrics were either preferentially eliminated or did not enter mitosis. Thus the radiation-induced damage can be underevaluated depending on the time between radiation exposure and the induction of proliferation. These results may have relevance for biodosimetry studies or for evaluations of the efficacy of radiotherapy which are based on the frequencies of chromosomal aberrations.     

In vitro apoptosis in peripheral blood mononuclear cells induced by low-dose radiotherapy displays a discontinuous dose-dependence

Purpose: Cells undergoing apoptosis contribute to the regulation of activated mononuclear cells (Voll et al. 1997). Low-dose radiotherapy (LD-RT) is known to improve inflammatory symptoms, but the mechanism of action is still unclear. The aim of this study was to investigate the rate of apoptosis of peripheral blood mononuclear cells (PBMC) induced by LD-RT within the therapeutic dose range of anti-inflammatory RT. Materials and methods: PBMC were isolated from venous blood of ten healthy volunteers and were irradiated with single doses between 0.1 and 3.0Gy. Apoptotic nuclei were detected by flow cytometry after propidium iodide (PI) triton staining, and apoptotic cells were detected by annexin V/PI staining and cell scatter analysis. Since apoptotic cells display increased cytoplasmatic granularity and concomitant reduced cell size, they can be distinguished from viable cells in forward/side scatter (FSC/SSC) histograms. Apoptotic PBMC were further subtyped by double staining with annexin V and directly labelled monoclonal antibodies recognizing the lineage-specific surface markers CD4, CD8, and CD19, respectively. The apoptosis rate of irradiated cells was analysed in a time and dose dependent fashion and was compared to a sham-irradiated control. Results: After irradiation, a dose-dependent increase in apoptosis was observed, with a discontinuity (plateau or peak) between 0.3Gy and 0.7Gy in 9/10 donors (90%) and 59/80 samples (74%). 8/10 donors (80%) and 38/80 samples (47%) showed not only a discontinuous increase with a plateau but a relative maximum of apoptosis peaking within the dose range of 0.3Gy and up to 0.7Gy. Conclusion: LD-RT induces a relative maximum of apoptosis in PBMC in the does range between 0.3Gy and 0.7Gy. This may contribute to its anti-inflammatory effect observed clinically.     

Let-7和miR-24在紫外线B诱导的细胞凋亡中的作用

目的 研究let-7和miR-24在紫外线B(UVB)诱导的细胞凋亡中的可能作用。方法 NIH3T3细胞受50 J/m²UVB照射后,用Hoechest 33342/PI染色观察其凋亡情况;RT-PCR检测let-7和miR-24的表达水平。利用在线数据库PicTar等预测它们的靶基因,并用GOstat软件对这些靶基因进行功能分类。结果 荧光显微镜下,NIH3T3细胞经UVB照射后可见典型的凋亡和坏死细胞;let-7和miR-24在UVB照射组的表达水平较对照组明显增加。用GOstat进行功能分类后发现,casp3、bcl2l2、map3k1和cdk5等基因同时也是UVB诱导的细胞周期调节的靶基因。结论 let-7和miR-24可能参与UVB诱导的细胞凋亡。     

Studies on radiation-induced apoptosis in G0 human lymphocytes

Purpose: To determine the relationships between the frequencies of radiation-induced chromosomal alterations and the extent of apoptosis in G₀ human lymphocytes.

Material and methods: G₀ human peripheral blood lymphocytes (HPBL) were X or γ-irradiated, in the presence or absence of the repair inhibitor cytosine arabinoside (Ara-C). Directly after irradiation, a part of the lymphocytes were stimulated to grow while the rest were stimulated 48 h after irradiation. These lymphocyte cultures were analysed for induction of chromosomal aberrations. A subset of lymphocytes was kept in G₀ and analysed for cell viability, apoptosis and p53 expression.

Results: The fraction of cells bearing dicentrics was reduced in lymphocytes stimulated to grow 48 h post irradiation as compared to lymphocytes stimulated immediately after irradiation. The decrease in the frequency of dicentrics correlated with the increase in the number of apoptotic cells. The operative apoptotic pathway in irradiated Go lymphocytes was dependent on the expression of p53.

Conclusions: The radiation-induced apoptotic response of G₀ lymphocytes is p53 dependent and increases with the time they are held in G₀. When mitogen was added 48 h after irradiation, cells with dicentrics were either preferentially eliminated or did not enter mitosis. Thus the radiation-induced damage can be underevaluated depending on the time between radiation exposure and the induction of proliferation. These results may have relevance for biodosimetry studies or for evaluations of the efficacy of radiotherapy which are based on the frequencies of chromosomal aberrations.     

重离子辐射对人外周血T淋巴细胞生物学性能的影响

目的研究重离子对人外周血T淋巴细胞增殖、凋亡等生物学性能的影响并探讨其机制,为肿瘤放射治疗的辐射防护提供实验依据和基础。方法 Ficoll分离法分离人外周血T淋巴细胞,采用12C重离子束坪区照射,照射样品能量为70 MeV、LET=29 keV/μm,照射剂量为1.0和2.0 Gy,剂量率为0.5 Gy/min。分别于照射后12、24h,RT-PCR检测凋亡相关基因Bcl-2,Bax,Caspase3,Caspase8和Caspase9的表达;于照射后24、48 h,CCK8法检测细胞增殖能力;于照射后24、48 h,采用AnnexinV-PE/7-AAD、AnnexinV-FITC/PI法检测凋亡发生,并采用RT-PCR检测凋亡相关蛋白Bcl-2、Bax和Caspase3的表达。结果重离子照射可明显抑制人外周血T淋巴细胞的增殖,随着剂量增大,抑制作用更加明显。同时,重离子照射可促进T淋巴细胞的凋亡,特别是对于晚期凋亡的诱导作用（P〈0.01）。RT-PCR检测结果显示,重离子辐射可抑制抗凋亡蛋白Bcl-2的表达,促进促凋亡蛋白Bax和Caspase3的表达（P〈0.01）。结论重离子辐射可显著影响抑制T淋巴细胞的增殖并促进其凋亡。     

Alpha-tocopherol succinate-mobilized progenitors improve intestinal integrity after whole body irradiation

Abstract

Purpose: The objective of this study was to elucidate the action of α-tocopherol succinate (TS)- and AMD3100-mobilized progenitors in mitigating radiation-induced injuries.

Material and methods: CD2F1 mice were exposed to a high dose of radiation and then transfused intravenously with 5 million peripheral blood mononuclear cells (PBMC) from TS- and AMD3100-injected mice after irradiation. Intestinal and splenic tissues were harvested after irradiation and cells of those tissues were analyzed for markers of apoptosis and mitosis. Bacterial translocation from gut to heart, spleen, and liver in TS-treated and irradiated mice was evaluated by bacterial culture.

Results: We observed that the infusion of PBMC from TS- and AMD3100-injected mice significantly inhibited apoptosis, increased cell proliferation in the analyzed tissues of recipient mice, and inhibited bacterial translocation to various organs compared to mice receiving cells from vehicle-mobilized cells. This study further supports our contention that the infusion of TS-mobilized progenitor-containing PBMC acts as a bridging therapy by inhibiting radiation-induced apoptosis, enhancing cell proliferation, and inhibiting bacterial translocation in irradiated mice.

Conclusions: We suggest that this novel bridging therapeutic approach that involves the infusion of TS-mobilized hematopoietic progenitors following acute radiation injury might be applicable to humans as well.     

Inhibition of UVB-induced oxidative damage and apoptotic biochemical changes in human lymphocytes by 2,5-dihydroxy-3-undecyl-1,4-benzoquinone (embelin)

Abstract

Purpose: The present study investigates the inhibition of Ultraviolet B (UVB, 290–320 nm) radiation-induced oxidative damage in peripheral blood human lymphocytes by embelin extracted from Embelia ribes.

Materials and methods: Embelin was extracted, purified and characterized. Prior to inhibitory assessment, a maximum concentration of embelin that was non-toxic was determined. Six experimental groups, including respective controls were made to assess the inhibitory effect of embelin for the selected concentrations of 10 and 20 μg/ml. For the experimental groups; lymphocytes (1 × 10⁶ cells) were pre-treated with the chosen concentration of embelin for a period of 60 min and then exposed to UVB for 30 min. UVB radiation inhibitory effect of embelin assessed by measuring antioxidant and lipid peroxidation levels, deoxyribonucleic acid (DNA) damage, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) at scheduled time points after irradiation.

Results: Pre-treatment of lymphocytes with embelin prevents UVB-induced oxidative damage. An increase in antioxidant levels in irradiated cells in the presence of embelin and UV absorbance of embelin could be the reason for the decrease in lipid peroxidation level and prevention of DNA damage by UVB radiation.

Conclusion: Embelin prevents oxidative stress induced by UVB irradiation via its antioxidant property.     

电离辐射对T淋巴细胞IL-2分泌和细胞毒活性的影响

正常人外周血单个核细胞（ＰＢＭＣ）体外经１～６Ｇｙγ射线照射后，间接免疫荧光法分析受照Ｔ细胞Ｔ细胞抗原受体（ＴＣＲ）、ＣＤ＿３及ＣＤ＿（２３）阳性细胞百分率，Ｈ￣３－ＴｄＲ掺入及释放法测定白细胞介素－２（ＩＬ－２）分泌及Ｔ细胞细胞毒活性，免疫细胞化学法分析Ｔ细胞内ＴＣＲ及ＣＤ＿３表达．结果表明，Ｔ细胞ＴＣＲ、ＣＤ．及ＣＤ＿（２５）表达及ＩＬ－２分泌和细胞毒活性皆呈照射剂量依赖性降低．受照Ｔ细胞ＩＬ－２分泌及细胞毒活性抑制在一定程度上与细胞表面ＴＣＲ、ＣＤ＿３及ＣＤ＿（２５）表达减少、活性损伤有关，而细胞表面ＴＣＲ和ＣＤ＿３表达降低可能与大量ＴＣＲ及ＣＤ＿３在受照细胞胞浆内堆积有关．     

Naive and memory T cell subsets are differentially mobilized during physical stress

This study examined the naive and memory phenotypic profiles of CD4+ and CD8hi T cells that were mobilized to the peripheral circulation during a combination of aerobic exercise and heat stress, determining expression of the adhesion molecules CD62L and CD11a on the recruited cells. Twelve recreationally active males (age 27.1 +/- 5.3 yr, height 1.77 +/- 0.08 m, mass 76.9 +/- 12.0 kg, VO2peak 43.9 +/- 6.7 mL x kg(-1) x min(-1)) completed a 40 min bout of cycle ergometry at 65 % of VO2peak while immersed to mid-chest in a water bath at 39 degrees C. Venous blood samples were collected before (T0), during (T40) and 30 min after (T70) exposure to combined exercise and heat stress. Specimens were analyzed by three-colour flow cytometry for CD4+ and CD8hi T cell expression of CD45RO, CD11a and CD62L. Some 80 % of the CD4+ T cells that were mobilized were of the CD45RO memory phenotype, with the numbers of CD11alo and CD62L+ cells increasing more than those of CD11ahi and CD62L- cells. For the CD8hi cells, there was a more equal recruitment of CD45RO- naive (43 %) and CD45RO+ memory (57 %) cells. The majority (84 %) of recruited CD8+ cells were CD11ahi; there was a trend to predominance of CD62L- cells (57 %) for the memory subset, but with almost equal recruitment of CD62L+/- for the naive subset. We conclude that the exercise + heat stress induced trend to an increase in CD4+ T cells is linked in some way to memory phenotype; it cannot be explained simply by a high density expression of CD11a and lack of the lymph node homing receptor (CD62L). Furthermore, although mobilization of CD8hi T cells is not linked to memory phenotype, a high density expression of CD11a and a lack of the lymph node homing receptor are important determinants of CD8hi T cell mobilization.     

X-irradiated human lymphocytes with unstable aberrations and their preferential elimination by p53/survivin-dependent apoptosis

PURPOSE: To investigate whether unstable types of chromosomal aberrations are more effective in priming apoptotic cell death in comparison with stable ones. Also, to highlight the phase of the cell cycle at which apoptosis occurs and the mechanism of its execution. MATERIALS AND METHODS: G0 human peripheral blood lymphocytes were X-irradiated in the presence or absence of the repair inhibitor cytosine arabinoside (Ara-C). After irradiation, the lymphocytes were analysed for induction of dicentrics, translocations, apoptosis, p53 and survivin expression at various recovery times. RESULTS: A preferential elimination of cells bearing dicentrics with respect to those with balanced translocations was observed. There was a time-dependent correlation between the decrease in the frequency of dicentrics and the increase in the per cent of apoptotic cells. Most of the apoptotic cells were labelled with bromodeoxyuridine and were mononucleated in cytochalasin B-treated cells cultures (blocked cytokinesis). However, after continuous colcemid treatment, the apoptotic pathway was not induced. Moreover, in the G2/M-phase, an increase in p53 and a decrease in survivin occurred that were X-ray and Ara-C dose dependent. CONCLUSIONS: The apoptotic process is primed when the dicentric-bearing human peripheral blood lymphocytes attempt to exit from metaphase. It is possible that unstable aberrations generate changes in the mitotic spindle causing mechanical tension at the kinetochore, activating the mitotic checkpoint and the execution of p53/survivin-dependent apoptosis.     

低剂量辐射对脐血的免疫刺激作用

目的：探讨低剂量辐射对脐血T淋巴细胞膜分子表达，IL－2分泌及LAK细胞体外抗肿瘤活性的影响。方法：新鲜分离的脐血淋巴细胞及LAK前体细胞接受低剂量γ射线照射，分别用直接免疫荧光标记流式细胞术，MTT法及3H-TdR释放实验检测T淋巴细胞膜分子的表达，IL－2分泌的LAK体外杀伤肿瘤靶细胞（K562，HL－60）活性。结果：（1）62mGyγ射线照射后，脐血淋巴细胞CD3，TCR／CD3复合物，CD4，CD8分子表达显著上调，且均在4－24h，人随时间推移而逐步增强，CD4／CD8比值无显著性变化；（2）62mGy γ射线照射后，脐血单个核细胞上清IL－2活性随培养时间推多逐渐增强，不同时间点比较差异均有显著性（P＜0．05）；（3）脐血LAK细胞对K562和HL－60的杀伤活性与成人外周血相比差异无显著性（P＞0．05），接受低剂量辐射的脐血LAK细胞对K562和HL－60的细胞毒性显著高于非照射组（P＜0．01），结论：低剂量辐射可促进脐血T淋巴细胞的成熟，活化和信号的转导及IL－2的分泌，增强脐血LAK杀伤肿瘤靶细胞的细胞毒活性，从而可能在脐血移植中加速免疫功能重建，增强移植物抗白血病效应。     

严重急性呼吸综合征肺脏及肺外器官细胞凋亡及其机制的研究

目的 探讨SARS冠状病毒(SARS-CoV)诱导的细胞凋亡在SARS发病机制中的意义。方法 采用原位末端标记(TUNEL)法与Cytokeratin(CK)及CD3、CD8、CD20、CD68单克隆抗体免疫组化双染色方法,对6例SARS死亡患者的肺及肺外组织进行多种细胞凋亡状况的研究,并以免疫组化法检测凋亡相关蛋白Fas、Fas配体(FasL)、Bcl-2和P53的表达。结果 与正常组织比较,SARS患者全身多器官组织细胞凋亡数目明显增多,尤以肺脏和免疫器官为甚,主要的凋亡细胞类型为CK阳性肺泡上皮细胞、终末支气管黏膜上皮细胞、CD3细胞、CD8细胞,以及少部分CD20’细胞和CD68’巨噬细胞。Fas蛋白主要于SARS肺组织内浸润的单个核细胞胞膜及胞质内表达,而FasL主要分布于SARS-CoV感染的靶细胞,尤其是上述凋亡细胞内,肺及免疫器官内少数细胞亦表达FasL,但Bcl-2及P53表达明显下调。结论 SARS-CoV诱导的广泛且迅速的细胞凋亡可能为SARS患者肺脏及免疫器官的主要细胞损伤机制之一;SARS-CoV诱导的主要凋亡细胞与体内SARS-CoV主要的感染靶细胞相吻合;表达Fas的致敏T淋巴细胞与表达FasL,的靶细胞结合介导的细胞凋亡可能为SARS-CoV诱导细胞凋亡的重要机制之一,而Bcl-2和P53的表达下调可能参了细胞凋亡过程。     

Flt3配体联合其他细胞因子对受照射小鼠免疫系统的作用研究

目的：研究Flt3配体（FL）在受照射小鼠免疫系统恢复中的作用。方法：采用F－800血细胞自动计数仪行外周血细胞计数及血细胞分类计数，流式细胞仪分析外周血淋巴细胞表型。结果：照射前应用FL或照射后联合应用FL，IL－11，EPO和G－CSF等细胞因子，能有效地促进受照小鼠外周血白细胞和淋巴细胞的恢复，对CD8^ 细胞的恢复作用尤为明显，同时使CD4^ /CD8^ 细胞比值较早恢复正常，提高受照射小鼠的生存率，结论：FL不但能促进辐射损伤机体造血功能的恢复，对免疫系统的亦具有重要的作用，FL单独或与其他细胞因子联合应用，对辐射损伤动物具有明显的防护和治疗效应。