Long-term combination treatment with clozapine and filgrastim in patients with clozapine-induced agranulocytosis

Short-term treatment with granulocyte colony-stimulating factor has been successful in reducing the duration of clozapine-induced agranulocytosis. Long-term combination treatment with filgrastim and clozapine in patients with clozapine-induced agranulocytosis has only been described in two previous cases. We describe three patients with schizophrenia who developed granulocytopenia or agranulocytosis during treatment with clozapine and who did not respond to other antipsychotics. The patients received long-term combination treatment with clozapine and filgrastim. Using a combination treatment with filgrastim and clozapine, the psychotic symptoms were successfully controlled and no haematological complications were observed during the follow-up periods of 11, 30 and 48 months, respectively. Our cases suggest that long-term treatment with filgrastim might be a useful, but exceptional, treatment approach in patients who have developed clozapine-induced granulocytopenia or agranulocytosis.     

Testing the hypothesis that vitamin C deficiency is a risk factor for clozapine-induced agranulocytosis using guinea pigs and ODS rats

The use of clozapine is limited by a relatively high incidence of drug-induced agranulocytosis. Clozapine is oxidized by bone marrow cells to a reactive nitrenium ion. Although many idiosyncratic drug reactions are immune-mediated, the fact that patients with a history of clozapine-induced agranulocytosis do not immediately develop agranulocytosis on rechallenge suggests that some other factor may be responsible for the idiosyncratic nature of this reaction. The reactive nitrenium ion is very rapidly reduced back to clozapine by vitamin C, and many schizophrenic patients are vitamin C deficient. We set out to test the hypothesis that vitamin C deficiency is a major risk factor for clozapine-induced agranulocytosis using a vitamin C deficient guinea pig model. Although the vitamin C deficient guinea pigs did not develop agranulocytosis, the amount of clozapine covalent binding in these animals was less than we had previously observed in samples from rats and humans. Therefore, we studied ODS rats that also cannot synthesize vitamin C. Vitamin C deficient ODS rats also did not develop agranulocytosis, and furthermore, although covalent binding in the bone marrow was greater than that in the guinea pig, it was not increased in the vitamin C deficient ODS rats relative to ODS rats that had adequate vitamin C in their diet. Therefore, it is very unlikely that vitamin C deficiency is a major risk factor for clozapine-induced agranulocytosis.     

Mitchell B. Balter Award. Human leukocyte antigen-A1 predicts a good therapeutic response to clozapine with a low risk of agranulocytosis in patients with schizophrenia

Several studies indicate an association between human leukocyte antigens (HLA) and clozapine-induced agranulocytosis. The authors have previously reported a significantly increased frequency of HLA-A1 among patients with schizophrenia who do not respond to conventional drugs, but do respond to clozapine treatment. In this study, the authors addressed the question of whether the same association is found in patients developing granulocytopenia or agranulocytosis. The frequency of the HLA-A1 allele in patients with clozapine-induced agranulocytosis or granulocytopenia was low (11.5%), whereas HLA-A1 was associated with a good therapeutic response to clozapine at an allele frequency of 58%. The frequency of HLA-A1 is 20% in the Finnish population. These results suggest that HLA-A1 may predict a good therapeutic outcome and a low risk of agranulocytosis and, thus, enable defining a subgroup of patients with schizophrenia in whom clozapine treatment could be started early to stop the disease from progressing.     

牛磺酸对心肌缺血损伤细胞凋亡与Fas/FasL基因表达变化的影响

目的探讨大鼠心肌缺血损伤心肌细胞凋亡与Fas/FasL基因表达变化及牛磺酸对其的影响。方法结扎冠状动脉制备心肌缺血模型,转移酶介导脱氧尿苷三磷酸缺口末端标记法检测心肌凋亡细胞,免疫组织化学法检测Fas/FasL蛋白水平,反转录-聚合酶链反应(RT-PCR)法分析Fas基因mRNA表达变化。结果心肌缺血后心肌细胞凋亡指数、Fas/FasL蛋白阳性染色细胞指数及Fas基因的mRNA表达水平均明显增加,心肌组织超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量升高,Ca2+-ATP酶活性降低。牛磺酸能明显降低心肌细胞凋亡指数,Fas基因mRNA表达及Fas/FasL蛋白阳性染色细胞指数,抑制心肌组织MDA的生成,提高Ca2+-ATP酶活性。结论牛磺酸对心肌缺血的心肌细胞凋亡与Fas/FasL基因表达水平增高有较好的拮抗作用。     

Olanzapine treatment after clozapine induced agranulocytosis

Clozapine is an atypical antipsychotic with a significant incidence of agranulocytosis. Olanzapine resembles clozapine structurally; however, it lacks a halogen, which has been implicated in agranulocytosis. Both agents have a similar pharmacological profile. We therefore studied olanzapine in patients with a history of clozapine-induced agranulocytosis. Two patients with severe clozapine-induced agranulocytosis and no benefit from classic neuroleptics were treated with olanzapine with informed consent. Psychosis improved in both patients and no hematological changes were noted. Olanzapine may be a safe treatment alternative in patients with a history of clozapine agranulocytosis. Copyright © 1998 John Wiley & Sons, Ltd.     

5-氟尿嘧啶诱导Jurkat细胞凋亡及Fas、FasL的表达

目的探讨5-氟尿嘧啶（5-FU）诱导Jurkat细胞株的凋亡和Fas、FasL的表达。方法不同浓度的5-FU分别处理Jurkat细胞12h和24h后,流式细胞仪检测细胞表达CD95、CD95L的百分率。结果与对照组相比,5-FU在10、20、40μg.mL-1浓度下明显促进Jurkat细胞表达Fas、FasL;且5-FU在24h比处理12h有更强的诱导效果。结论 5-FU可显著提高Jurkat细胞凋亡率,并增强Fas、FasL的表达率。     

The Fas signalling pathway and its role in the pathogenesis of cancer

Tumor cells frequently exhibit de novo expression of Fas ligand (FasL/CD95L). Coupled with resistance to Fas-mediated apoptosis, FasL expression enables many cancers to deliver a pre-emptive strike or 'counterattack' against the immune system. New studies also indicate that FasL expression on tumor cells could confer a double advantage to these cells by stimulating their own proliferation. However, pro-inflammatory effects of FasL have also been observed. New findings are beginning to reconcile the paradoxical effects of FasL, with the clinical significance of the Fas counterattack only beginning to emerge.     

雷米普利对实验性心力衰竭大鼠心肌细胞凋亡和Fas Fas配体基因表达的影响

目的探讨实验性心力衰竭大鼠心肌细胞凋亡和心肌组织Fas、Fas配体(FasL)蛋白及信使核糖核酸(mRNA)表达的变化及血管紧张素转换酶抑制剂(ACEI)干预的影响及意义。方法将30只健康Wistar大鼠,随机分为假手术组、慢性心力衰竭组和雷米普利组各10只。通过缩窄Wistar大鼠腹主动脉建立慢性心力衰竭模型,以雷米普利进行干预,对照观察血流动力学、心肌细胞凋亡、心肌组织Fas、FasL蛋白及其mRNA表达的变化。结果与假手术组相比,慢性心力衰竭组左心室舒张末压、心率显著升高(P<0.01);收缩压、舒张压、平均动脉压、左心室收缩压、左心室内压最大收缩率、左心室内压最大舒张率显著降低(P<0.01)。雷米普利组舒张压、左心室收缩压、左心室舒张末压、心率显著低于慢性心力衰竭组(P<0.01),左心室内最大收缩率、左心室内最大舒张率显著高于慢性心力衰竭组(P<0.01)。慢性心力衰竭组心肌细胞凋亡指数、心肌组织Fas、FasL蛋白及其mRNA表达水平显著低于慢性心力衰竭组(P<0.05)。结论慢性心力衰竭的发生、发展过程中有心肌细胞凋亡的变化及Fas/FasL系统的参与;心力衰竭大鼠心肌细胞凋亡指数、心肌组织Fas、FasL蛋白及其mRNA表达水平增高,雷米普利长期干预慢性心力衰竭,能够降低细胞凋亡及Fas、FasL基因的表达,可能与其减少Fas/FasL系统介导的细胞凋亡的发生、改善心功能有关。     

An association between clozapine-induced agranulocytosis in schizophrenics and HLA-DQB1*0201

A group of 18 Israeli, clozapine-treated, schizophrenia patients underwent molecular and serological HLA typing in order to determine whether the major histocompatibility complex is associated with the development of clozapine-induced agranulocytosis. While under treatment with clozapine, 2 of the 18 patients developed agranulocytosis (total white blood cell count <3000/mm(3) and absolute polymorphonuclear count <500/mm(3)) and 3 developed granulocytopenia (total white blood cell count <3500/mm(3) and absolute polymorphonuclear count <1000/mm(3)). HLA-DQB1*0201 was present in all five patients who developed agranulocytosis or granulocytopenia (5/5; 100%), but in only 54% (7/13) of the patients who did not develop those complications. These findings indicate that DQB1*0201 or a gene located nearby could be involved in clozapine-induced agranulocytosis.     

慢性乙型肝炎病毒感染对外周血单个核细胞中凋亡分子表达的影响及其与免疫功能的相关性

目的 研究慢性乙型肝炎病毒(HBV)感染对外周血单个核细胞中凋亡分子表达的影响及其与免疫功能的相关性.方法 选择76例慢性乙型肝炎(CHB)患者和体检的54例健康志愿者,分别作为CHB组和对照组,采集血清并测定凋亡分子含量、采集外周血单个核细胞并测定凋亡分子表达量以及免疫细胞含量.结果 CHB组患者血清中凋亡分子Fas、FasL、Caspase-3、Caspase-6、Caspase-8的含量以及外周血单个核细胞中Fas、FasL、Caspase-3、Caspase-6、Caspase-8的mRNA含量均显著高于对照组;CHB组患者外周血中CD3+ CD4+T细胞、CD3+ CD8+T细胞、CD16+ CD56+ NK细胞的百分比及CD4+/CD8+的比例均显著低于对照组;外周血单个核细胞中Fas、FasL、Caspase-3、Caspase-6、Caspase-8的mRNA含量与CD3+ CD4+T细胞、CD3 +CD8+T细胞、CD16+ CD56+自然杀伤(NK)细胞的百分比呈负相关.结论 慢性HBV感染能够增加外周血单个核细胞中凋亡分子的表达,进而造成T淋巴细胞和NK细胞凋亡、抑制细胞免疫应答和非特异性免疫应.     

Clozapine induces oxidative stress and proapoptotic gene expression in neutrophils of schizophrenic patients

The present study examined cellular effects of the atypical antipsychotic drug clozapine on blood cells of treated patients with and without clozapine-induced agranulocytosis (CA). Blood from one patient who commenced clozapine treatment was examined at weekly intervals for 128 days. Olanzapine-treated (n = 5) and polymedicated (n = 14) schizophrenic patients, as well as healthy subjects (n = 19) and septic shock patients (n = 8), were studied for comparison. We observed dramatically increased numbers of native neutrophils stained for superoxide anion production (P < or = 0.005, n = 10) and significantly elevated expression levels of the proapoptotic genes p53 (P < or = 0.020), bax alpha (P < or = 0.001), and bik (P < or = 0.002) in all tested non-CA patients (n = 19) and CA patients (n = 4). In non-CA patients, the expression of these genes did not correlate to the percentage of apoptotic neutrophils (2.0% +/- 1.3%), but in CA patients about 37% of the neutrophils show morphologic signs of apoptosis (P < or = 0.001). Under G-CSF therapy of CA, the number of apoptotic neutrophils and the expression of the proapoptotic genes decreased significantly. In conclusion, high production of reactive oxygen species in neutrophils of clozapine-treated patients, together with increased expression of proapoptotic genes, suggests that neutrophils are predisposed to apoptosis in schizophrenic patients under clozapine therapy. The correlation between drug and proapoptotic markers was highest for clozapine and bax alpha as well as superoxide anion radicals. This indicates oxidative mitochondrial stress in neutrophils of clozapine-treated patients which probably contributes to the induction of apoptosis and sudden loss of neutrophils and their precursors in CA patients.     

Testing the hypothesis that selenium deficiency is a risk factor for clozapine-induced agranulocytosis in rats

Clozapine is an effective atypical antipsychotic associated with a relatively high incidence of drug-induced agranulocytosis. It forms a reactive nitrenium ion metabolite upon oxidation by peripheral neutrophils and their precursors in the bone marrow. Although the mechanism of this idiosyncratic drug reaction is still unknown, the observation that it does not occur rapidly on rechallenge of patients with a history of clozapine-induced agranulocytosis suggests that it is not immune-mediated. Previous studies by other research groups had found that patients on clozapine had lower plasma and red blood cell levels of selenium. The reactive metabolite of clozapine reacts with glutathione, and therefore, it is likely that it also binds to selenocysteine-containing proteins, such as glutathione peroxidase, thioredoxin reductase, and protein disulfide isomerase. We set out to test the hypothesis that clozapine-induced agranulocytosis is associated with selenium deficiency with rats on a selenium-deficient diet. We studied the effects of clozapine on selenium levels and the effect of selenium deficiency on leukocyte and neutrophil counts and clozapine covalent binding. We did not observe any significant difference between clozapine-treated rats given a selenium-adequate or deficient diet. Therefore, it is unlikely that selenium deficiency is a major risk factor for clozapine-induced agranulocytosis.     

Human leukocyte antigen typing, response to neuroleptics, and clozapine-induced agranulocytosis in jewish Israeli schizophrenic patients.

The atypical antipsychotic agent clozapine is known to be effective in schizophrenic patients refractory to other medications; however, it induces agranulocytosis in approximately 1-2%. In Jews, this complication is associated with the haplotype HLA B38,DR4,DQ3. The aim of the present study was to determine which human leukocyte antigen (HLA) antigens are involved in clozapine-induced agranulocytosis. We performed HLA typing in 88 Jewish Israeli schizophrenic patients and in 127 ethnically matched healthy individuals. Thirty-eight patients responsive to standard antipsychotic medications were treated with haloperidol, and 50 refractory patients received clozapine. A trend was noted for elevated rates of HLA B38 among control individuals and clozapine-treated patients of Ashkenazi origin compared to individuals of non-Ashkenazi origin, but the findings failed to reach statistical significance. No association was found between HLA class I antigens and the response to haloperidol or clozapine. Neutropenia developed in two clozapine-treated patients and agranulocytosis in one. Two of these three patients were of Ashkenazi origin, and both demonstrated the HLA B38 phenotype. Although the findings did not reach a statistical significance because of the small number of patients, they may support an association between clozapine-induced neutropenia/agranulocytosis and Ashkenazi origin and the HLA B38 phenotype. The rate of agranulocytosis in our sample (2%) is similar to the usual cumulative risk of agranulocytosis but in contrast to its high frequency among Jewish American patients. One possible explanation for this difference is the high rate of Ashkenazi patients in the American sample and the preponderance of non-Ashkenazi patients in our population.     

Participation of the Fas-Signaling System in the Initiation of Germ Cell Apoptosis in Young Rat Testes after Exposure to Mono-(2-Ethylhexyl) Phthalate

The Fas-signaling system is composed of the interacting proteins Fas (CD95/APO-1) and Fas ligand (FasL, CD95L, APO-1L) and is proposed to act in the testis as a paracrine signaling mechanism by which FasL-expressing Sertoli cells initiate apoptosis of Fas-bearing germ cells. Here we describe alterations in the expression of Fas and FasL in the testis after the intimate physical association between Sertoli cells and germ cells is disrupted by exposure to the Sertoli cell toxicant mono-2-(ethylhexyl) phthalate (MEHP). Young, 28-day-old Fisher rats were treated with MEHP (2 g/kg po) and killed 0, 3, 6, and 12 h after exposure. Immunohistochemical analyses revealed a significant increase in the numbers of Fas-positive germ cells as well as increases in the expression of Sertoli cell FasL. Western blot analysis demonstrated a time-dependent increase in the production of the soluble form of FasL after MEHP exposure and suggests that it may participate in triggering apoptosis in germ cells that have lost their intimate association with the Sertoli cells. Measurement of Fas in cytosolic and membrane fractions of testis homogenates by Western blot analysis revealed a significant shift of Fas expression into the membrane fraction after MEHP exposure. Taken together, these observations indicate that the Fas-mediated paracrine signaling mechanism participates in triggering apoptosis of germ cells despite the loss of their close physical association with Sertoli cells. A working model is presented to explain the involvement of the Fas-system in stimulating germ cell apoptosis after MEHP exposure.     

Involvement of Fas/FasL system in apoptotic signaling in testicular germ cells of male Wistar rats injected i.v. with microcystins

Previous studies have shown that gonads were the second target organ of microcystins (MCs), and that MCs exposure exerted obvious toxic effects on male reproductive system of mammals. However, relevant molecular evidences are still lacking. Fas-signaling pathway plays a key role in toxicant-induced germ cell apoptosis. This study was to evaluate the responses of Fas/FasL system related genes and proteins in testes of rats injected intravenously with MCs. Enhanced apoptosis of germ cells in the testes of MCs-treated rats was detected by the terminal deoxynucleotidyl transferase-mediated deoxy-UTP nick end labeling (TUNEL) associated with up-regulation of the Fas/FasL system. Both Fas and FasL protein expression were induced evidently from 1 h post-injection, and this high expression level maintained throughout the experiment. In addition, the activation of caspase-8 and caspase-3 protein was also observed, which were indicators of apoptosis. These results suggested the likely involvement of Fas/FasL system in the MCs-induced germ cell apoptosis. It is also suggested that MCs can cause damage to Sertoli cells directly.     

基因转移FasL诱导人脑胶质瘤细胞凋亡的体外实验研究

目的：探讨体外基因转移Fas配体（Fas-Ligand,FasL)对恶性人脑胶质瘤细胞凋亡的影响，方法：用携带人FasL cDNA的缺陷型重组腺病毒载体（Ad-FL)，在体外转导5株人脑胶质瘤细胞，并使其表达，通过流式细胞仪，RT－PCR，TUNEL法及荧光显微镜分别进行Fas/FasL表达检测和相关凋亡检测，分析，结果：RT－PCR和流式细胞仪检测5株胶质瘤细胞表达均表达Fas，不表达FasL,而Ad-FL转导的5株胶质瘤细胞均能表达FasL,Fas表达水平与抗Fas抗体诱导胶质瘤细胞凋亡敏感性无相关性，Ad-FL能显著诱导5株胶质细胞瘤在体外凋亡或抑制其生长，结论：重组腺病毒FasL在体外诱导人脑胶质瘤凋亡效果显著。     

Upregulation of Fas and FasL expression in testosterone-induced apoptosis of macrophages

To the best of the authors' knowledge, there have been few reports on the effect of testosterone on the apoptosis of macrophages. In this report, we studied the effect of testosterone on the apoptosis of bone marrow-derived macrophages (BMMs) and the function of the Fas/Fas ligand (FasL) system in the process. Results showed that testosterone treatment in vitro at the physiological concentration of 10 nM did not induce the apoptosis of BMMs. However, BMMs underwent apoptosis when treated at higher concentrations of testosterone (100, 200 and 400 nM). Testosterone-induced apoptosis was associated with the enhanced expression of Fas, FasL, and caspase-8. These data suggest that the Fas/FasL system may play an important role in the testosterone-induced apoptosis of macrophages.