人脂联素球状结构域基因的原核表达及多克隆抗体的制备

目的:构建人脂联素球状结构域(gAd)基因的原核表达载体PET-28a(+)-gAd,诱导表达并纯化重组gAd蛋白,制备多克隆抗体。方法:以人基因组为模板,用PCR方法扩增人脂联素球状结构域(gAd)基因,构建原核表达载体PET-28a(+)-gAd,转化大肠杆菌BL21(DE3),IPTG诱导蛋白表达,经SDS-PAGE,免疫印迹法检测并鉴定表达产物,表达的目的蛋白用镍亲和层析柱纯化后免疫新西兰大白兔,制备多克隆抗体。结果:原核表达载体PET-28a(+)-gAd转化大肠杆菌BL21(DE3),经IPTG诱导表达,获得gAd重组蛋白,免疫印迹证实能与抗his标签检测抗体结合,制备的多克隆抗体经间接ELISA法测得效价为1∶32 000。免疫印迹证实,抗血清不仅能特异性地识别gAd蛋白,还能识别脂联素蛋白,而不与非特异性蛋白结合。结论:成功构建原核表达载体PET-28a(+)-gAd,并表达、纯化重组蛋白gAd,制备的多克隆抗体特异性好,效价较高,为进一步的研究奠定了基础。     

人精子肌动蛋白样蛋白7a蛋白在大肠杆菌系统的表达纯化及多克隆抗体制备

目的 在大肠杆菌系统表达并纯化人精子肌动蛋白样蛋白7a(ACTL7a)的N段(1-70),制备兔抗ACTL7a多克隆抗体.方法 构建重组表达质粒pGEX-6p-1-ACTL7a(1-70),以重组质粒转化E.coli BL21(DE3),筛选阳性重组菌,IPTG诱导目的蛋白表达,通过镍离子金属螯合树脂和谷胱甘肽琼脂糖凝胶4B树脂两次亲和纯化和分子筛分离目的蛋白;以表达的ACTL7a(1-70)蛋白免疫新西兰大白兔,制备抗ACTL7a的多克隆抗体.ELISA检测抗体效价,Western blot法鉴定抗体特异性,免疫荧光组织化学技术检测ACTL7a在曲精小管细胞的表达.结果 经IPTG诱导,在大肠杆菌中表达出目的蛋白ACTL7a(1-70),纯化后免疫新西兰大白兔,成功获得抗血清.血清效价达到1∶160000以上,且具有良好的特异性.结论 成功构建了ACTL7a基因的原核表达载体,并在大肠杆菌中诱导表达,经纯化获得高纯度的目的蛋白;制备出兔抗ACTL7a抗体,效价及特异性均良好.     

H37Rv结核分枝杆菌蛋白脯氨酸-谷氨酸8(PE8)的表达及其兔多克隆抗体制备

目的克隆Rv1040c结核分枝杆菌脯氨酸-谷氨酸8(PE8)基因、构建pET28a-PE8重组载体和表达纯化PE8蛋白,制备抗PE8多克隆抗体。方法利用重组克隆技术,将PE8基因克隆至原核表达载体pET28a,测序鉴定后,转化至大肠杆菌BL21(DE3),用0.5 mmol/L异丙基-β-D-硫代吡喃半乳糖苷(IPTG)诱导表达、稀释复性与纯化。用纯化PE8蛋白免疫新西兰大白兔,制备多克隆抗体,间接ELISA和Western blot法进行效价及特异性鉴定。结果成功构建pET28a-PE8原核表达载体, ITPG诱导后PE8蛋白在大肠杆菌主要以包涵体的形式表达,复性后纯化PE8蛋白纯度达90%,纯化多克隆抗体效价为1∶430 080以上,能与PE8蛋白发生特异性反应。结论大肠杆菌表达的PE8重组蛋白免疫新西兰大白兔获得高效价的多克隆抗体。     

兔抗小鼠IL-23p19多克隆抗体的制备和鉴定

目的制备兔抗小鼠白细胞介素23p19(IL-23p19)多克隆抗体。方法利用分子克隆技术构建重组表达质粒p ET-16b-IL-23p19,转化大肠杆菌BL21(DE3),异丙基-β-D-硫代半乳糖吡喃糖苷(IPTG)诱导蛋白表达,SDS-PAGE及Western blot法分析鉴定蛋白,镍柱亲和层析纯化制备蛋白;以此蛋白为免疫抗原免疫新西兰大白兔,获得抗血清,并利用亲和层析法纯化抗血清,制备兔抗小鼠IL-23p19多克隆抗体;采用ELISA检测抗体效价;Western blot法检测抗体特异性。结果重组表达载体p ET-16b-IL-23p19构建正确且IL-23p19蛋白能够在大肠杆菌BL21(DE3)中有效表达。通过多次IL-23p19蛋白免疫新西兰大白兔,成功制备兔抗小鼠IL-23p19多克隆抗体。ELISA检测确定新西兰大白兔血清效价达1∶256 000,Western blot法证实兔抗小鼠IL-23p19多克隆抗体能特异性识别小鼠IL-23p19蛋白。结论成功制备了兔抗小鼠IL-23p19多克隆抗体,抗体具有高的效价和较好的特异性。     

11型HPV E7蛋白的表达及其多克隆抗体的制备

目的构建人11型乳头瘤病毒(HPV 11)E7蛋白的原核表达载体,表达纯化后制备抗HPV11E7蛋白的多克隆抗体。方法构建pGEX-4T2-HPV11E7原核表达载体,异丙基-β-D-硫代半乳糖苷(IPTG)诱导大肠杆菌表达可溶性融合蛋白GST-HPV11E7,纯化获取11型HPVE7蛋白。将HPV11E7蛋白免疫新西兰大白兔获得抗HPV11E7的多克隆抗体,用蛋白G琼脂糖纯化获得IgG型多克隆抗体。Western blot法及免疫荧光染色检测该抗体的效价及特异性。结果 SDS-PAGE结果显示,经IPTG诱导6 h后可表达出高水平可溶性GST-HPV11E7融合蛋白。纯化后免疫新西兰大白兔获得抗HPV11E7的血清,纯化获得了IgG型多克隆抗体。Western blot及免疫荧光染色结果显示,兔抗HPV11E7 IgG具有效价高和特异性强的特点。结论成功表达了HPV11E7蛋白并制备了效价较高、特异性较好的IgG型兔抗HPV11E7蛋白多克隆抗体。     

小鼠visfatin抗体的制备及应用

目的: 制备高效价抗visfatin抗体, 探测visfatin在前脂肪细胞成脂分化过程中在空间上表达情况.方法: 克隆鼠内脂素visfatin基因的蛋白编码区全长序列, 构建其原核表达载体pET28a-visfatin, 然后在E.coli(BL21)中诱导大量以包涵体形式表达, 提取包涵体并用Ni-NTA 亲和层析柱纯化蛋白, 并以此为抗原免疫新西兰大白兔制备多克隆抗体.以纯化后的抗血清为一抗, Western blot检测小鼠肝、肌肉等组织中visfatin的分布.结果: SDS-PAGE及Western blot显示原核表达载体pET28a-visfatin在大肠杆菌中诱导表达, 融合蛋白能够被抗his mAb识别.免疫新西兰大白兔获得抗体效价在1∶ 25 600以上.结论: 用制备得到的抗体对小鼠心、肝、肺、脾、脂肪、肌肉组织样品做Western blot鉴定, 结果表明visfatin在各组织中均有表达, 其中脾和脂肪组织中表达量高于其他组织.     

小鼠IL-1α多克隆抗体的制备及应用

目的:构建小鼠白细胞介素-1α原核表达载体,表达并纯化IL-1α蛋白,制备兔抗鼠IL-1α多克隆抗体,并对抗体特性进行初步的鉴定。方法:利用RT-PCR技术,从BALB/c小鼠脾脏cDNA中扩增出IL-1α的全长基因,酶切后连接至pET32a(+)原核表达载体,重组载体测序正确后转化至BL21(DE3)大肠杆菌。利用蛋白质原核表达自动诱导方案成功表达重组蛋白。重组蛋白经电洗脱纯化后用以免疫新西兰大白兔,获得了抗小鼠IL-1α的多克隆抗体,ELISA检测抗体效价。Western blot和流式细胞术(FCM)检测抗血清的特异性。结果:成功构建了重组表达载体pET32a(+)-IL-1α,表达的重组蛋白纯化后免疫新西兰大白兔,得到的多克隆抗体ELISA显示抗体效价可达1∶25 600。Western blot和FCM分析该抗体能特异性结合IL-1α。结论:利用重组的IL-1α蛋白成功制备了高效价、高特异性的兔抗IL-1α抗体,为进一步研究IL-1α的生物学功能奠定了基础。     

FILIP-1L蛋白的原核表达及多克隆抗体制备

目的:表达、纯化GST-FILIP-1L融合蛋白,制备FILIP-1L多克隆抗体。方法:pGEX-4T3-FILIP-1L重组质粒转化E.coliBL21大肠杆菌,IPTG诱导GST-FILIP-1L融合蛋白表达,Glutathion Sepharse 4B纯化GST-FILIP-1L融合蛋白。将纯化的GST-FILIP-1L融合蛋白免疫新西兰大耳白兔,制备FILIP-1L多克隆抗体,用ELISA方法检测多克隆抗体效价,Western blot检测多克隆抗体与FILIP-1L蛋白、细胞转染FILIP-1L蛋白及细胞FILIP-1L蛋白的结合能力。结果:在大肠杆菌中诱导出高表达的FILIP-1L融合蛋白,经Glutathion Sepharse 4B纯化后免疫新西兰大耳白兔,获得了高效价的抗FILIP-1L多克隆抗体,亲和层析获得纯度较高的多克隆抗体,WB检测显示多克隆抗体能够与FILIP-1L蛋白、293细胞转染FILIP-1L蛋白及肝癌细胞FILIP-1L蛋白结合。结论:成功表达、纯化了GST-FILIP-1L融合蛋白,制备了高效价的抗FILIP-1L多克隆抗体,为研究FILIP-1L蛋白生物学功能提供了有用的实验工具。     

肿瘤睾丸抗原OY-TES-1氨基端截短蛋白及其多克隆抗体的制备

目的获得原核表达的OY-TES-1氨基端截短蛋白(OY-TES-1-N),并制备其多克隆抗体。方法扩增编码OY-TES-1-N 268个氨基酸(A6-R273)的cDNA序列;将PCR产物插入原核表达载体pMAL-C2,构建重组质粒,并转化DH5α菌;通过蓝白斑筛选、DNA测序筛出阳性菌;在优化条件下用IPTG对阳性菌进行诱导表达MBP/OY-TES-1-N融合蛋白;上Amyloseresin亲和层析柱纯化,行Western blot鉴定。以融合蛋白作为抗原免疫新西兰白兔制备抗血清,经活化琼脂糖微球纯化后,采用ELISA法及Western blot法分别检测抗血清的效价和多克隆抗体的特异性。结果成功诱导表达出MBP/OY-TES-1-N融合蛋白。以该蛋白免疫新西兰兔制备抗血清,抗体效价为1∶1 000,Western blot检测证实该抗体能与目的蛋白发生特异性结合。结论成功地表达并纯化了MBP/OY-TES-1-N融合蛋白,并制备了特异性多克隆抗体。     

小鼠IL-1α多克隆抗体的制备及应用

目的:构建小鼠白细胞介素-1α原核表达载体,表达并纯化IL-1α蛋白,制备兔抗鼠IL-1α多克隆抗体,并对抗体特性进行初步的鉴定.方法:利用RT-PCR技术,从BALB/c小鼠脾脏cDNA中扩增出IL-1α的全长基因,酶切后连接至pET32a(+)原核表达载体,重组载体测序正确后转化至BL21( DE3)大肠杆菌.利用蛋白质原核表达自动诱导方案成功表达重组蛋白.重组蛋白经电洗脱纯化后用以免疫新西兰大白兔,获得了抗小鼠IL-1α的多克隆抗体,ELISA检测抗体效价.Western blot和流式细胞术(FCM)检测抗血清的特异性.结果:成功构建了重组表达载体pET32a(+)-IL-1α,表达的重组蛋白纯化后免疫新西兰大白兔,得到的多克隆抗体ELISA显示抗体效价可达1∶25 600.Western blot和FCM分析该抗体能特异性结合IL-1α.结论:利用重组的IL-1α蛋白成功制备了高效价、高特异性的兔抗IL-1α抗体,为进一步研究IL-1α的生物学功能奠定了基础.     

Propagation of granulocytic Ehrlichia spp. from human and equine sources in HL-60 cells induced to differentiate into functional granulocytes.

Ehrlichia spp. from human and equine sources in the northeastern Unites States were detected by PCR, isolated, and propagated in the HL-60 promyelocytic leukemia cell line. Growth of Ehrlichia from both equine and human sources was enhanced by addition of retinoic acid, which causes granulocytic differentiation of the HL-60 cells. DNA sequencing of a portion of the 16S rDNA gene supported the hypothesis that the same pathogen was responsible for both equine and human granulocytic ehrlichiosis.     

Exploitation of interleukin-8-induced neutrophil chemotaxis by the agent of human granulocytic ehrlichiosis

The agent of human granulocytic ehrlichiosis (HGE) is an obligate intracellular bacterium with a tropism for neutrophils; however, the mechanisms of bacterial dissemination are not yet understood. Interleukin-8 (IL-8) is a chemokine that induces neutrophil migration to sites of infection for host defense against pathogens. We now show that HGE bacteria, and the HGE-44 protein, induce IL-8 secretion in a promyelocytic (HL-60) cell line that has been differentiated along the neutrophil lineage with retinoic acid and in neutrophils. Infected HL-60 cells also demonstrate upregulation of CXCR2, an IL-8 receptor, but not CXCR1. Human neutrophils migrate towards Ehrlichia sp.-infected cells in a chemotaxis chamber assay, and this movement can be blocked with antibodies to IL-8. Finally, immunocompetent and severe combined immunodeficient mice administered CXCR2 antisera, and CXCR2(-/-) mice that lack the human IL-8 receptor homologue, are much less susceptible to granulocytic ehrlichiosis than are control animals. These results demonstrate that HGE bacteria induce IL-8 production by host cells and, paradoxically, appear to exploit this chemokine to enhance infection.     

Cyclic AMP levels and cellular kinetics during maturation of human promyelocytic leukemia cells

Differentiation of human promyelocytic leukemia cells (HL-60) in response to several classes of inducing agents is characterized by the sequential appearance of granulocytic or monocytic markers. Compounds that increase intracellular cAMP in HL-60 cells induce a program of maturation in which cells demonstrate early functional phagocytic properties. Cyclic nucleotide metabolism was studied during monocytic and granulocytic differentiation of the HL-60 cell line. In synchronous and nonsynchronous cell cultures, cyclic AMP levels were raised 300-fold or 25-fold in response to N6, O2-dibutyryl adenosine 3':5'-cyclic monophosphate or the combination of prostaglandin E2 and theophylline, respectively. No reproducible changes in intracellular adenosine 3':5'-cyclic monophosphate levels occurred in response to retinoic acid or dimethyl sulfoxide, suggesting that changes in adenosine 3':5'-cyclic monophosphate levels alone do not mediate cell maturation induced by these compounds. Agents that increased intracellular cyclic AMP in HL-60 cells slowed the progress through the S and G2-M phase of the cell cycle, whereas other agents such as dimethyl sulfoxide stimulated cells through this same period.     

Initial characterization of a cytokine which induces differentiation and cytolytic activity in HL-60 promyelocytic leukemia cells: evidence that the cytokine is distinct from other known differentiation-active cytokines

In this paper we report that, like dimethyl sulfoxide (DMSO), retinoic acid (RA), and conditioned medium (CM) from lectin-stimulated mononuclear leukocytes, CM from a human null cell leukemia line (Reh) induces HL-60 promyelocytic leukemia cells to respond in an enhanced manner to phorbol diester (PDE). Furthermore, Reh-CM induces PDE-resistant HL-60-1E3 cells to respond to PDE and lyse target cells. Additionally, both HL-60 and HL-60-1E3 cells exposed to Reh-CM for 3 days produce superoxide anion and express cell surface antigens present on mature mononuclear phagocytes. No colony-stimulating factor (CSF) or interferon (IFN) activity was detected in Reh-CM, and differentiation activity (DA) was not removed from Reh-CM by insolubilized anti-IFN gamma. While Reh-CM is antiproliferative against a panel of cell lines, its spectrum of activity is different than tumor necrosis factor (TNF) alpha, and neither TNF alpha nor TNF beta inhibit proliferation of HL-60-1E3 or induce these cells to respond to PDE. The differentiation factor (DF) material has been partially purified by ammonium sulfate precipitation and is non-dialyzable; unstable to heat, acid, or alkali treatment; and the activity is not blocked by anti-IL-6 or anti-IFN alpha. The data presented in this paper suggest the presence of a differentiation-inducing factor which is distinct from CSF, IFN alpha or -gamma, TNF alpha, or -beta, or IL-6, which may play a role in the differentiation of malignant (leukemic) and normal cells of the myelomonocytic lineage.     

Regulation and function of Bcl-2 during differentiation-induced cell death in HL-60 promyelocytic cells.

Polymorphonuclear leukocytes are generated by differentiation of early myeloid precursors. Once fully differentiated, blood neutrophils are programmed to die rapidly and are removed by tissue macrophages. In normal myeloid cells, the death mechanism seems to be coupled to the differentiation pathway and is accomplished by a process termed apoptosis. In the present study, we have examined the role of Bcl-2 in the differentiation pathways of the promyelocytic cell line HL-60. Treatment of HL-60 with retinoic acid or phorbol ester, which induced neutrophil or macrophage-like cell differentiation, respectively, resulted in progressive loss of cellular viability and internucleosomal DNA degradation. In HL-60, differentiation and apoptosis were coupled to down-regulation of the Bcl-2 protein. Overexpression of Bcl-2 by gene transfer inhibited apoptosis triggered by terminal differentiation of HL-60. Yet, Bcl-2 did not alter the expression of surface markers or other phenotypic changes that are induced upon myeloid differentiation. In contrast to HL-60, another immature myeloid cell line, K562, did not produce Bcl-2 but expressed a related protein, Bcl-xL, that functions as a repressor of apoptotic cell death. K562 has been shown to be relatively resistant to a variety of apoptotic stimuli. Incubation of HL-60 and K562 with inhibitors of macromolecular synthesis induced apoptosis, which appeared earlier in HL-60 than in K562. Interestingly, Bcl-2 overexpression protected K562 cells from apoptosis induced by inhibitor of macromolecular synthesis but it had little or no effect on HL-60 cells. We conclude that although differentiation and apoptosis proceed simultaneously, they can be uncoupled by expression of Bcl-2. Down-regulation of Bcl-2 appears to be part of the differentiation pathway and may serve to facilitate the apoptotic response.     

DnaJ类分子伴侣PBP基因的原核表达及兔抗PBP抗体的制备

目的:在原核系统中表达DnaJ类分子伴侣感光受体外周蛋白结合蛋白(PBP)基因,并制备兔抗PBP的抗体鉴定其特性。方法:应用RTPCR从人胎脑组织总RNA中扩增PBPcDNA。测序后将其克隆到表达载体pET28a中,并在大肠杆菌中以IPTG诱导表达。表达产物经NiNTA亲和层析柱纯化后,用SDSPAGE进行鉴定。以所获纯化的PBP免疫新西兰白兔,制备兔抗PBP抗体。抗体的效价及特异性用Westernblot进行测定和分析。结果:扩增和克隆出了720bp的PBP基因。构建的重组质粒pET28aPBP在大肠杆菌中得到高表达,诱导表达的蛋白存在于包涵体和细菌裂解上清中,纯化的PBP经SDSPAGE鉴定呈单一条带。以纯化的PBP免疫兔,制备了兔抗PBP抗体。Westernblot鉴定证实,该抗体可与原核表达的PBP特异性结合,抗体效价为1∶1600。结论:在原核细胞中表达了具有生物学活性的PBP,并以其为免疫原制备了兔抗PBP的抗体,为进一步研究PBP的结构与生物学活性奠定了基础。     

hp450RAI质粒转染对HL—60细胞功能及IFN—α表达的影响

目的探讨细胞内一种细胞色素 P45 0 (hp45 0 RAI,也称 CYP2 6 )表达、视黄酸 (RA)代谢与细胞增殖功能的相互关系。方法采用脂质体介导的质粒转染、流式细胞仪分析、逆转录 - PCR及高效液相色谱 (HPL C)分析等实验技术方法做有关分析研究。结果 12 .5× 10 - 7m ol/ L 全反式 RA(ATRA)处理 HL- 6 0细胞 3d未诱导明显的 hp45 0 RAI表达 ,脂质体介导的质粒转染可使 HL- 6 0细胞稳定表达 hp45 0 RAI;2单纯 hp45 0 RAI转染未对 HL- 6 0细胞 ATRA代谢及 ATRA诱导的 HL- 6 0细胞增殖抑制产生显著影响 ,而联合应用 P45 0酶抑制剂 Ketoconazole或 IFN- α则使 HL- 6 0细胞 ATRA代谢减慢 ,ATRA增殖抑制作用增强。结论 RA敏感 HL- 6 0细胞中影响 RA代谢的主要细胞色素 P45 0可能并非 hp45 0 RAI,P45 0酶抑制剂或IFN- α能协同 ATRA抑制细胞增殖 ,后者可能与 HL- 6 0细胞 ATRA代谢减慢及 IFN- α表达增强有关。     

睾丸肿瘤抗原MAGE-E1基因片段的克隆及其在大肠杆菌中的表达

目的：克隆及表达人胶质瘤特异性抗原MAGE-E1基因片段。方法：从人胶质瘤细胞系BT-325提取总RNA，用RT—PCR从中扩增出MAGE-E1基因片段。将MAGE—E1基因片段插入载体pGEM—Teasy中，经全自动序列分析仪测序正确后，再克隆至表达载体pGEX—4T—2中，构建重组表达载体pGEX—4T—2—MAGE—E1，并转化大肠杆菌进行表达。结果：用1mmoL／L异丙基-β-D-硫代半乳糖苷(IPTG)诱导5h，MAGE—E1蛋白的表达即达高峰。SDS—PAGE及凝胶密度扫描分析表明，表达出MT约41000大小的蛋白，占菌体总蛋白35％。结论：该基因片段的高效表达为进一步制备其抗体，以及制备肿瘤疫苗奠定了基础。     

Development of the cell contact-mediated accessory function for T-cell proliferation in a human promyelocytic leukaemia cell line, HL-60, by 1,25-dihydroxyvitamin D3.

A human promyelocytic leukaemia cell line, HL-60 cells, did not show accessory cell (AC) function to potentiate the proliferation of human T cells induced by anti-CD3 antibody coupled to latex beads (alpha T3-L). This was found to be at least due to the inability of HL-60 cells to express certain molecules which are inducible with interferon-gamma (IFN-gamma) on mature monocytes and are necessary for interaction with T cells. HL-60 cells acquired the ability to express such surface molecules by stimulation with IFN-gamma when the cells were pretreated with 1,25-dihydroxyvitamin D3 (Vit D). The effect of Vit D was reversible, that is, the AC function of the HL-60 cells was lost when the cells were cultured in Vit D-free medium for 7 days. It was also found that HL-60 cells treated with IFN-gamma and then with Vit D did not show significant AC function. The flow cytometric analysis showed that the expression of HLA-DR and intercellular adhesion molecule-1 (ICAM-1) was highly increased on HL-60 cells when stimulated with IFN-gamma after treatment with Vit D. The expression of ICAM-1 was also induced with IFN-gamma on untreated cells but in lower amounts. Monoclonal antibodies against ICAM-1 and HLA-DR inhibited the alpha T3-L-induced T-cell proliferation, indicating that these molecules are at least required for contact-mediated AC function. Thus our study revealed that HL-60 cells express cell surface interaction molecules necessary for potentiating the T-cell proliferation through two steps, differentiation with Vit D to mature monocyte-like cells followed by stimulation with IFN-gamma.     

Heterogeneity of the response to inducers of differentiation and to cytostatics of tumor cell populations

The purpose of the experiments was to establish whether individual cells of a tumor cell population, or clonal lines derived from its express the differentiated phenotype, or respond heterogeneously following treatment with inducers of differentiation or with cytostatic drugs. The human cell lines used in this study were: HL-60 promyelocytic leukemia, K562 erythroleukemia, BHM-97 and A2058 melanoma, and A-1, A-2, A-4 and A-6 clones of A2058 line. Inducers of differentiation were phorbol myristate acetate (PMA), dimethylsulfoxide (DMSO) and retinoic acid (RA); cytostatics: adriamycin (ADM), 5-fluorouracil (5-FU), dacarbazine (DTIC), cis-platin (platidiam, PD) and arabinosyl cytosine (ara-C). Expression of the differentiated phenotype was shown by cell attachment (HL-60), hemoglobin production (K562), dendrit formation (A2058, BHM-97). Individual cells expressed the differentiated phenotype heterogeneously in all types of cell populations. Clone A-4 was the most, and clone A-6 the least sensitive to PMA. The drug sensitivity of the clones was different and drug-dependent. It is concluded that induction of differentiation as another approach to therapy of cancer, similar to anticancer drug therapy, also implies disadvantages due to population heterogeneity. Combinations of cytostatics with differentiation inducers might result in improved therapeutic effects.