MG患者外周血Th17细胞与AChR抗体产生的关系研究

目的探讨重症肌无力(MG)患者外周血中Th17细胞及相关细胞因子白细胞介素17(IL-17)在MG发病中的作用。方法收集40例MG患者和10名健康人(对照组)外周血标本,采用流式细胞术检测外周血单个核细胞(PBMCs)中Th17细胞比例,反转录酶-聚合酶链锁反应(RT-PCR)检测PBMCs中维甲酸受体相关孤儿受体γt(RORγt)mRNA水平,ELISA检测血清中IL-17水平,放射免疫沉淀法检测血清中抗乙酰胆碱受体抗体(AChR-Ab)滴度;分离PBMCs中CD4~+T细胞和CD19~+B细胞与金黄色葡萄球菌肠毒素B(SEB)进行共培养,培养系统中加入人IL-17和(或)IL-21中和抗体,放射免疫测定法检测培养液中AChR-Ab滴度。采用MG评分(quantitative MG scoring system,QMGs)对MG的严重程度进行评估,并对MG患者的Th17细胞比例、RORγt mRNA和IL-17水平与病情QMGs的相关性,以及MG患者抗AChR-Ab滴度与PBMCs中Th17细胞比例的相关性进行分析。结果 MG患者PBMCs中Th17细胞比例[1.11%(0.90%,1.34%)]高于健康对照组Th17细胞比例[0.26%(0.08%,0.36%)](z=5.494,P0.001),且与疾病严重程度呈正相关(r=0.4394,P=0.0046);血清中IL-17水平和PBMCs中RORγt mRNA相对表达[分别71.46(53.91,104.76)pg/mL、2.63(1.94,3.12)]均较健康对照组[分别18.82(12.73,29.80)pg/mL、1.13(0.98,1.28)]显著增高(均P0.001);MG患者血清中抗AChR-Ab滴度[2.34(1.19,3.60)nmol/L]较健康对照组[-0.08(-0.24,-0.03)nmol/L]显著增高(z=4.662,P0.001),且与Th17细胞比例呈正相关(r=0.7066,P=0.0001)。MG患者外周血T、B细胞与SEB共培养后抗AChR-Ab水平高于未加入SEB时及健康对照(均P0.01);加入抗人IL-21或IL-17中和抗体后,两者AChR-Ab滴度与未加入抗体时AChR-Ab滴度比较均降低(均P0.05),且均仍高于MG患者未加入SEB时及健康对照(P0.01);在培养上清中同时加入抗人IL-21和IL-17中和抗体时AChR-Ab滴度明显低于加入单种抗体时,而与未加入SEB时及健康对照差异无统计学意义(均P0.05)。结论 MG患者外周血中Th17细胞可能通过IL-17促进AChR-Ab产生,参与疾病的病理过程。     

Th17细胞及其效应分子IL-17在HAM/TSP患者体内的变化及Tax蛋白对IL-17的影响

目的 研究Th17细胞及其效应分子IL-17在HTLV-Ⅰ相关性脊髓病/热带痉挛性截瘫(HTLV-Ⅰassociated myelopsthy/tropical spastic paraparesis,HAM/TSP)患者中的变化及Tax蛋白对IL-17的影响.方法 分别应用ELISA法和流式细胞技术检测HAM/TSP患者CSF上清液中的IL-17水平及外周血Th17细胞的百分率.应用RNAi干扰技术抑制Tax蛋白的表达,并用ELISA法检测干扰后细胞培养悬浮液中IL-17的表达.结果 HAM/TSP患者脑脊液上清中IL-17含量(4.58±0.70) pg/mL较对照组(0.76±0.17) pg/mL显著升高(P＜0.01);HAM/TSP患者外周血中Th17细胞的百分率(2.00％±0.64％)较对照组(0.41％±0.24％)显著升高(P＜0.01).RNAi技术干扰Tax蛋白表达后,IL-17水平(5.04± 1.27) pg/mL较未干扰组细胞培养悬浮液中IL-17水平(7.69±2.11) pg/mL显著降低(P＜0.05).结论 Th17细胞及其效应分子IL-17在HAM/TSP患者体内显著提高,提示在其发病机制中发挥一定作用,而且IL-17的表达水平受Tax蛋白调控.     

雌激素受体及多巴胺受体在泌乳素腺瘤的表达

目的研究雌激素受体(ESR)及其亚型mRNA、多巴胺受体(D2R)及其亚型mRNA在泌乳素腺瘤中的表达。方法应用逆转录酶聚合酶链式反应(RT-PCR)测定30例泌乳素腺瘤标本ESR1mRNA、ESR2mRNA、第五外显子缺失的1型雌激素受体(△5-Del-ESRl mRNA)及D2RmRNA的表达,研究其表达水平与患者性别、肿瘤体积、侵袭性及泌乳素(PRL)水平的关系。结果男性和绝经后女性患者肿瘤ESR1 mRNA表达高于育龄女性患者;侵袭性泌乳素腺瘤高于非侵袭性肿瘤;PRL≥1 000 ng/ml的患者△5-Del-ESRl mRNA表达水平较PRL1 000 ng/ml的患者明显增高。D2RmRNA异构体的表达水平与泌乳素腺瘤生物学行为有关系,D2SmRNA的表达水平在侵袭性与非侵袭性泌乳素腺瘤中存在显著差异,D2SmRNA在侵袭性泌乳素腺瘤中呈低水平表达。结论 ESR1及其亚型△5-Del-ESRl mRNA、D2R及其亚型mRNA表达与泌乳素腺瘤PRL分泌及肿瘤侵袭有关。     

帕金森病患者外周血Th17/Treg平衡及相关细胞因子水平测定及意义

目的探讨帕金森病(PD)患者外周血Th17/Treg平衡及相关细胞因子含量变化的意义。方法收集50例PD患者(PD组)及50例健康体检者(Control组),采集所有研究对象外周血。采用流式细胞仪检测外周血中Th17细胞及Treg细胞含量;采用ELISA检测血浆中细胞因子TGF-β、IL-6和IL-17水平。结果流式细胞计数结果显示,PD组的外周血Treg细胞和Th17细胞水平较Control组均显著增加(P均0.01),Treg细胞的增长程度明显大于大于Th17细胞,同时PD组Treg/Th17细胞比较Control组也明显增加(P均0.01)。ELISA检测结果显示,与Control组相比,PD组的血浆TGF-β1、IL-6及IL-17含量均有显著增加(P均0.01)。结论 PD患者的外周血Treg/Th17平衡存在失衡,提示PD病理过程可能与其外周血Treg/Th17失衡有关。     

脑出血患者外周血及脑组织中IL-17、TGF-β的表达及意义

目的通过研究脑出血(ICH)患者白介素-17(IL-17)、转化生长因子-β(TGF-β)的变化,探讨ICH急性期免疫炎症反应及临床意义。方法采用酶联免疫吸附实验(ELISA)方法检测40例ICH患者外周血中IL-17、TGF-β的蛋白表达水平,应用反转录酶-聚合酶链锁反应(RT-PCR)方法检测患者外周血及出血灶周边脑组织IL-17mRNA和TGF-βmRNA表达水平。结果40例ICH患者外周血中IL-17蛋白及IL-17mRNA表达增高,TGF-β蛋白及TGF-βmRNA表达下降;出血灶周边脑组织标本中,IL-17mRNA和TGF-βmRNA表达均上调。结论急性ICH患者外周血及出血灶周边脑组织均发生炎症反应,并可能与血肿周围脑组织的损害相关。     

神经肽Y在人垂体腺瘤中组织学和分子生物学变化的研究

目的 探讨NPY在人垂体腺瘤细胞中的位置和表达,不同类型中的特点.方法 收集我院神经外科经手术和病理确诊的垂体腺瘤57例.免疫电镜研究NPY在垂体腺瘤细胞中的位置.免疫组化和RT-PCR检测NPY的表达.结果 (1)免疫电镜:NPY主要位于胞质的分泌颗粒中,其次位于粗面内质网和细胞基质中.(2)免疫组化:NPY在垂体腺瘤中总体表达的结果为59.6%(34/57);促性腺瘤91.7%,GH腺瘤和ACTH腺瘤均为66.7%,零细胞腺瘤和混合性腺瘤均为50%,PRL腺瘤为25%,它们间的差异有统计学意义(P=0.04).(3)RT-PCR:NPY mRNA在垂体腺瘤中均表达,其差异有统计学意义(P<0.01);促性腺瘤最高是PRL腺瘤的9.3倍、无功能腺瘤5.8倍、GH腺瘤2.7倍,其余组间的差异无统计学意义.结论 (1)人垂体腺瘤中存在NPY.(2)垂体腺瘤中的确有NPY表达,不同类型中的表达各有差异;促性腺瘤表达最高,PRL腺瘤表达最低.(3)为今后深入探讨NPY在垂体腺瘤中的作用奠定了基础.     

IL-6对视神经脊髓炎谱系病患者Th17/Treg失衡的调控机制研究

目的 研究调控白细胞介素(IL)-6对视神经脊髓炎谱系病(NMOSD)患者辅助性17型T细胞(Th17)/调节性T细胞(Treg)比值失衡的影响。方法 收集2019年1月至2020年12月就诊的9例AQP4-IgG阳性的NMOSD患者为NMOSD组和同期8例健康志愿者为对照组,收集并培养外周血单个核细胞(PBMC)后,分别予以IL-6或IL-6受体抑制剂共培养,采用流式细胞术检测Th17和Treg比例,流式微球检测技术检测调控IL-6水平后对Th17、Treg、IL-17、IL-10水平的影响。结果 NMOSD组PBMC细胞添加IL-6共培养后,可见Th17比例及Th17/Treg比值增高(均P<0.05)。添加IL-6阻滞剂共培养后,IL-10水平下降,Treg表达增加,Th17/Treg比值下降(均P <0.05)。结论 NMOSD患者PBMC中的外源性IL-6可以上调Th17比例而导致Th17/Treg比值失衡;但外源性IL-6受体阻滞剂可以升高IL-10水平,通过增加Treg比例恢复Th17/Treg比值平衡。     

过氧化物酶体增殖物激活受体γ在垂体腺瘤中的表达

目的 通过检测过氧化物酶体增殖物激活受体γ(PPARγ)在人垂体腺瘤组织中的表达,探讨其在垂体腺瘤中的相关机制.方法 通过免疫组化法确定经手术切除的83例垂体腺瘤组织细胞来源;采用RT-PCR、适时定量PCR检测研究83例垂体腺瘤组织及6例正常垂体组织PPARγ的mRNA表达量,采用Western blot法检测组织PPARγ蛋白质表达水平,分析不同类型垂体腺瘤组织之间核酸及蛋白水平表达量的差异.结果 GH腺瘤17例、PRL腺瘤15例、ACTH腺瘤18例、多激素腺瘤(MCPAs)17例、无功能腺瘤(NFAs)16例及正常对照组6例;mRNA水平检测显示所有垂体腺瘤组织的表达量均高于正常对照组,其中GH腺瘤的表达量最高,与其他组比较P＜0.05;蛋白水平检测显示GH腺瘤、PRL腺瘤、ACTH腺瘤及MCPAs的表达量均高于正常对照组(P＜0.05),GH腺瘤的表达量最高,NFAs的表达量与正常对照组差异无统计学意义(P＞0.05).结论 PPARγ转录及蛋白表达水平在人GH、PRL、ACTH及MCPAs垂体腺瘤组织中高表达,该基因与垂体腺瘤有一定的相关性,而无功能垂体腺瘤在核酸水平的表达量增高,蛋白水平的表达量不高,可能与激素的分泌水平有关;在GH腺瘤中的表达量最高,且与其他组相比,差异有统计学意义(P＜0.05),说明该类肿瘤与PPARγ的关系最为密切,可能与生长激素能刺激PPARγ的表达有关.     

侵袭性与非侵袭性泌乳素腺瘤细胞增殖活性的差异

目的　研究侵袭性与非侵袭性泌乳素 (PRL)腺瘤细胞增殖活性的差异。方法　检测 2 6例泌乳素腺瘤中细胞核增殖抗原 (PCNA)表达 ;用流式细胞仪 (FCM )检测相应腺瘤中S期细胞比例 ,比较侵袭性泌乳素腺瘤与非侵袭性泌乳素腺瘤PCNA表达与S期细胞比例的差异。结果　侵袭性PRL腺瘤中PCNA表达的阳性指数为 76 7±1 1 1 8;非侵袭性腺瘤中PCNA表达的阳性指数为 37 1± 1 0 33;两组比较 ,差别具有显著性 (P <0 0 5) ;侵袭性PRL腺瘤S期细胞比例为 1 3 57%± 2 1 6 % ;非侵袭性PRL腺瘤为 8 97%± 2 0 7% ,两组比较差别具有显著性 (P <0 0 5)。结论　PCNA表达与S期细胞比例的检测结果是一致的 ,侵袭性与非侵袭性PRL腺瘤相比 ,细胞增殖能力较强 ,复发率高     

IL-17及IL-17R在人脑胶质瘤中的表达

目的探讨IL-17及IL-17R在人正常脑组织、低级别胶质瘤、高级别胶质瘤中的表达,及其与胶质瘤级别的关系。方法正常脑组织、低级别胶质瘤、高级别胶质瘤标本分别20、23、22例,采用PCR法检测IL-17mRNA,PCR法及原位杂交法检测IL-17RmRNA,免疫组化法检测IL-17蛋白在各组中的表达。结果 IL-17mRNA在各组中仅见微量表达;IL-17RmRNA在各组中的表达无明显差异(P0.05);蛋白IL-17的表达在正常脑组织、低级别胶质瘤、高级别胶质瘤中依次增高,各组间差异均具有统计学意义(P0.05)。结论蛋白IL-17可能在胶质瘤的发生、发展中起重要作用。     

白细胞介素17及其受体在脑缺血损伤中作用的初步研究

目的 在建立小鼠大脑中动脉永久性栓塞模型(permanent middle cerebral artery occlusion,pMCAO)的基础上,探讨白细胞介素17(Interleukin-17,IL-17)及其受体IL-17 Receptor(IL-17R)在缺血脑组织中的表达及对神经元的损伤作用.方法 体内实验:通过线栓法建立小鼠永久性大脑中动脉栓塞模型,HE观察脑组织形态学改变,ELISA与免疫组织化学技术分别检测小鼠pMCAO血清及缺血脑组织中IL-17的表达.免疫荧光检测Th17及IL-17R的表达.体外实验:原代培养的神经元经氧糖剥夺(oxygen-glucose deprivation,OGD)处理2h,MTT检测不同剂量IL-17对神经元的损伤作用.结果 体内实验:ELISA结果 证实随着缺血时间延长,IL-17含量增加.与对照组相比,于24h出现差异(P24h<0.05,P2d、6d<0.001).免疫组织化学结果 显示,缺血侧脑皮质及血管周围存在IL-17的表达,经免疫荧光鉴定缺血脑组织中有T helper 17细胞(Th17)的表达;同时脑血管内皮细胞表达IL-17R.体外实验:MTT结果 显示IL-17加剧了神经元的厌氧损伤,与单纯神经元厌氧培养组相比有意义,P10ng/ml IL-17<0.05,P100ng/ml IL-17<0.01,且高浓度(100ng/ml)IL-17与低浓度(10ng/ml)IL-17对神经元的刺激干预相比较,高浓度的IL-17对神经元活性损伤大.结论 (1)IL-17与IL-17R参与了脑缺血损伤过程;(2)缺血侧脑实质内存在Th17及IL-17R的表达;(3)IL-17加剧了缺血缺氧条件对神经元有损伤作用,且存在剂量依赖性.

Abstract：

Objective To discuss the expression and the damage to neurons of the action of IL-17 and IL-17R during the process of cerebral ischemic with the model of mouse permanent middle cerebral artery occlusion(pMCAO).Method The model of mouse permanent middle cerebral artery occlusion wag made by introduction of an intraluminal nylon.The change of morphology of the brain tissue wag observe.the expression of IL-17 in serum and ischemic cortical was detected by EUSA and immunohistochemistry,respectively.The expression of Th17 and IL-17R were detected by double-immunofluoroscence.Neurons by primary culture were identified by immunofluorescence,and then detected the damage of IL-17 on neurons under the condition of Oxygen-Glucose Deprivation(OGD)with MTT.Results The level of IL-17 in serum revealed a gradually increased value beginning from 24h after pMCAO and significant differences at 24h,2d and 6d in comparison to control values(P24h<0.05,P2d,6d<0.001).There were Th17 and IL-17R expression in the ischemic tissue.Neurons with IL-17 cultured after OGD 2h had significant damage to neurons compared with pure neuron cultured after OGD 2h,P10ng/ml IL-17<0.05,P100ng/ml IL-17<0.01,and higher density of IL-17 had more serious damage to neurons.Conclusion IL-17 and IL-17R participate the process of cerebral ischemic.There is Th17 and IL-17R expression in ischemic brain.The effects of IL-17 which ale dose dependent aggravate the damage to neurons in ischemic injury.     

IL-17在中枢神经系统感染发病机制及鉴别诊断中的作用

目的 探讨IL-17有无参与结核性脑膜炎(TBM)、隐球菌性脑膜炎(CM)、病毒性脑膜脑炎(VM)这3类中枢神经系统感染的免疫反应和对这3类中枢神经系统感染的鉴别诊断有无提示意义.方法 选择自2008年2月至2009年12月在中山大学附属第三医院住院治疗的中枢神经系统感染患者112例,根据感染源不同分为TBM组、CM组和VM组.同时选择同期在该院住院的非中枢神经系统感染性疾病及非自身免疫疾病患者36例,归入对照组.用ELISA法测定IL-17、IL-12、IFN-γ在4组患者脑脊液中的浓度.结果 4组对象脑脊液中IL-17水平差异有统计学意义(P＜0.05),由高到低依次是CM组、TBM组、VM组和对照组.4组患者间IL-12、IFN-γ水平差异也有统计学意义(P＜0.05),其中TBM组和CM组患者脑脊液中的IL-12、IFN-γ的水平较VM组和对照组患者明显增高.TBM组患者脑脊液中IL-17与IL-12呈负相关(r=-0.311,P=0.033).IL-17、IL-12、IFN-γ与脑脊液白细胞数均呈正相关(r=0.219,0.434,0.341;P=0.031,0.027,0.001).利用脑脊液中IL-17的水平建立这3种疾病的ROC曲线,曲线下面积均大于0.7.结论 Th17免疫途径广泛的参与了这3种中枢神经系统感染的免疫应答,且可能与Th1免疫途径相互影响.IL-17检测有助于这3类中枢神经系统感染的鉴别诊断.

Abstract：

Objective To study the role of IL-17 in the pathogenesy and differential diagnosis of the 3 types of CNS infections (tubercular meningitis [TBM], cryptococcal meningitis [CM], viral meningoencephalitis [VM]). Methods One hundred and twelve patients with CNS infections,admitted to out hospital from February 2008 to December 2009, were chosen and divided into TBM group, CM group and VM group;another 36 patients without CNS infections either autoimmune disease at the same period were chosen as control group. ELISA was employed to determine the levels of IL-17,IL-12, IFN-γ in the cerebrospinal fluid in these 4 groups. Results IL-17 level in the cerebrospinal fluid of the 3 groups with CNS infections were obviously different, but all of them were significantly higher than that in control group (P＜0.05), with CM group enjoying the highest level, following by TBM group,VM group and control group. The levels of IL-12 and IFN-γ in patients with TBM and CM were higher than those in patients with VM and controls. Through the correlation analysis of IL-17, IL-12 and IFN-γ in patients with TBM, we found that IL-17 level was negatively correlated with IL-12 level (r=-0.3 11,P=0.033);the levels of these 3 cytokines were positively correlated with the quantity of leucocytes (r=0.219, 0.434 and 0.341, P=0.031, 0.027 and 0.001). ROC curves were established for differential diagnosis among these 3 groups according to CSF IL-17 levels, and all of the areas under the curve were bigger than 0.7. Conclusion Thl7 pathway is widely involved in the immune responses of CNS infection, and interacts with Thl pathway. The different levels of IL-17 in the cerebrospinal fluids in patients with various CNS infections may contribute to differential diagnosis.     

17-α-estradiol and 17-β-estradiol in hippocampus

Electrophysiological field potentials recorded from in vitro hippocampal slice preparations show responses to exogenous gonadal steroids added to the incubation medium. The peak effect of the addition of 17-beta-estradiol occurred at a 100 pmol concentration; the CA1 field potential was increased by an average of 148 percent. 17-alpha-estradiol, often used as a negative control in experiments demonstrating estrogen specificity of receptor binding sites and biological responses, had no effect on field potentials following addition of drug to the incubation medium. The addition of a 100 pmol concentration of 17-beta-estradiol to the same slices which had been pretreated with 17-alpha-estradiol, blocked the facilitatory response elicited by the 17-beta-estradiol administered alone. Since no enhancement of the field potential is observed with 17-beta-estradiol following pretreatment of 17-alpha-estradiol, this would support the hypothesis that hippocampal modulation by gonadal steroid hormones may be due to involvement of an estrogen receptor mediated phenomena.     

IL-17、RORγt在实验性自身免疫性神经炎中的表达

目的 观察Th17型细胞因子IL-17和Th17细胞特异性转录因子维甲酸受体相关孤儿受体γ的胸腺异构体(RORγt) mRNA在实验性自身免疫性神经炎(EAN)模型中的表达,以探讨Th17细胞在EAN中的作用.方法 用P253-78aa肽段免疫Lewis大鼠,建立EAN模型,观察大鼠发病情况和组织病理改变,并检测淋巴细胞增殖反应,用RT-PCR技术检测IL-17和RORγt在大鼠发病高峰期脾脏、淋巴结和坐骨神经中的表达.结果 EAN组大鼠在第14-16天发病高峰期时平均临床评分为(7.5±1.2),病理学检查可见明显炎性细胞浸润,对P253-78aa的刺激产生强烈淋巴细胞增殖反应,与对照组相比,IL-17和RORγt mRNA在脾脏、淋巴结和坐骨神经中的表达均显著升高(P<0.001).结论 IL-17和RORγt表达上调与EAN的发病相关.     

Genetically modified rodent models of SCA17

Spinocerebellar ataxia type 17 (SCA17) is a type of autosomal dominant cerebellar ataxia (ADCA) characterized by variable manifestations, including cerebellar ataxia, dementia, and psychiatric symptoms. Since the identification of a CAG repeat expansion in the TATA‐box binding protein (TBP ) gene in a patient with ataxia in 1999 and then verification of this expansion in patients with SCA17 in 2001, several SCA17 rodent models, including both knock‐in and transgenic models in mice and rats, have been established to explore the phenotypic features and pathogenesis of SCA17. These animal models revealed different pathological changes and phenotypes that are associated with the expression of mutant TBP protein and the CAG repeat lengths. It is important to understand how mutant TBP can cause differential pathological events in SCA17 animal models. In this review, we summarize and compare these animal models for the nature of transgenes and their expression as well as phenotypical features. We also discuss potential directions for future studies. © 2016 Wiley Periodicals, Inc.     

17O magnetic resonance imaging of the human brain

Abstract

Here we show the first example of in vivo oxygen-17 (¹⁷O) magnetic resonance imaging of the human in natural abundance. Two-dimensional fast multi-planar gradient recalled 90 deg echo (FMPGR/90) pulse sequence and three-dimensional projection reconstruction pulse sequence methods were used.     

The role of interleukin-17 in immune-mediated inflammatory myopathies and possible therapeutic implications

The idiopathic inflammatory myopathies are a heterogeneous group of autoimmune muscle disorders with distinct clinical and pathological features and underlying immunopathogenic mechanisms. Traditionally, CD4⁺ Th1 cells or CD8⁺ cytotoxic effector T cells and type I/II interferons have been primarily implicated in the pathogenesis of the inflammatory myopathies. The presence of IL-17A producing cells in the inflamed muscle tissue of myositis patients and the results of in vitro studies suggest that IL-17A and the Th17 pathway may also have a key role in these diseases. The contribution of IL-17A to other chronic inflammatory and autoimmune diseases has been well established and clinical trials of IL-17A inhibitors are now at an advanced stage. However the precise role of IL-17A in the various forms of myositis and the potential for therapeutic targeting is currently unknown and warrants further investigation.     

Characterization of chromosome 17 abnormalities in medulloblastomas

Loss of portions of chromosome 17p, usually through the formation of i(17qp) is a well-known finding in medulloblastomas. Loss of heterozygosity (LOH) studies, however, occasionally demonstrate loss of the more distal portions of 17p, a pattern which is more consistent with a terminal deletion. Here we use a combination of routine karyotyping, fluorescence in situ hybridization (FISH) and LOH studies on four medulloblastoma cell lines and one xenograft to demonstrate the spectrum of chromosome 17 abnormalities which occur in these tumors. Cell line D-556 Med showed a typical dicentric i(17q) and cell line D-721 Med showed two normal copies of chromosome 17 by all methods. Cell line D-425 Med showed loss of terminal 17p by LOH, while the karyotype showed what appeared to be an i(17q). FISH and chromosome 17 painting, however, demonstrated that the abnormal chromosome 17 was actually formed through an unbalanced translocation involving two copies of chromosome 17, with breakpoints at p12 and q11-1, an explanation which reconciled the cytogenetic and LOH findings. Cell line D 581 Med had a terminal deletion at 17p11.2. The finding of two cells with i(17q) in this case by interphase FISH suggests that the terminal deletion arose from breakage of an i(17q). Finally, xenograft D 690 Med showed LOH for regions distal to 17p12, whereas karyotyping, FISH using probes on 17p, and chromosome 17 painting showed two intact copies of chromosome 17. This pattern can be explained by homologous recombination. These data support the concept that the critical deletion of 17p can occur through a variety of mechanisms in the medulloblastoma. The losses may occur through typical i(17q), as well as other mechanisms such as terminal deletions, possibly through breakage of i(17q), unbalanced translocations and homologous recombination. Received: 26 March 1999 / Revised, accepted: 6 August 1999