人生长分化因子15单克隆抗体制备、鉴定及药用价值初探

目的:制备稳定分泌抗人生长分化因子15(GDF15)单克隆抗体(m Ab)的杂交瘤细胞系,并对其分泌的m Ab进行鉴定。方法:根据人GDF15氨基酸序列特征,设计合成了8条能够免疫产生GDF15特异性抗体的抗原多肽,与VLP载体偶联后,免疫雌性BALB/c小鼠,利用杂交瘤技术制备鼠源抗人GDF15的m Ab,用间接ELISA检测m Ab腹水效价。结果:获得针对7个抗原多肽的12株稳定分泌抗人GDF15的杂交瘤细胞系,腹水m Ab效价可达1×104~1×109。结论:获得了针对不同抗原多肽的抗人GDF15的特异性m Ab,为进一步研发以GDF15为靶点的单克隆抗体抗肿瘤药物奠定了基础。     

一株人源抗狂犬病病毒单克隆抗体的表位及中和活性的研究

目的通过ELISA相加试验和狂犬病毒(Rabies virus,RV)逃逸突变试验对一株人源抗狂犬病病毒单克隆抗体(human anti-rabies virus monoclonal antibody,Ab1)进行抗原表位分析。方法将已知表位的对照抗体(CR57和CR4098)和Ab1进行ELISA相加试验;以及对RV逃逸株氨基酸突变位点分析进一步验证Ab1针对的抗原表位,用小鼠中和试验(mouse neutralization test,MNT)分析Ab1的体内抗狂犬病病毒中和活性。结果 Ab1和CR57可同时与RV结合;与CR4098存在竞争,Ab1的逃逸株在氨基酸位点333、336发生突变,MNT检测体内中和活性为550.32 IU/mg,MNT和快速荧光灶抑制试验(rapid fluorescent focus inhibition test,RFFIT)结果基本一致。结论该抗体针对III号抗原表位且具有较高的抗狂犬病病毒中和活性。     

抗EHFV的独特型抗体在小鼠体内诱导免疫应答的研究

本文介绍用流行性出血热（EHF）病毒J10株制备单克隆抗体（McAb）,以及用7个McAb免疫家兔,使其产生抗EHF病毒McAb的抗体即抗独特型 抗体（Ab2).Ab2能在体外同出血热病人恢复期血清和EHF病毒免疫的兔血清发生特异性结合。再经EHF－McAb亲和层析法分离提纯Ab2,免疫BALb/c小鼠,将所获得的免疫血清（Ab3）用荧光和ELISA分别加以测定。结果表明,抗－抗独特型抗体可在体外识别EHF病毒,而不能同病病人恢复期血清发生结合,从而支持免疫网络学说,可能为我们提供一种新型的抗原来源途径。     

抗EHFV的独特型抗体在大鼠体内诱导免疫应答的研究

本文介绍用流行性出血热（EHF）病毒J10株制备单克隆抗体（McAb),以及用7个McAb免疫家兔,使其产生抗EHF病毒McAb的抗体即独特型抗体（Ab2）。Ab2能在体外同出血热病人恢复期血清和EHF病毒免疫的兔血清发生特异性结合。再经EHF－McAb亲和层析法分离提纯Ab2,免疫BALb/c小鼠,将所获得的免疫血清（Ab3）用荧光和ELISA分别加以测定,结果表明,抗－抗独特型抗体可在体外识别EHF病毒,而不能同病病人恢复期血清发生结合,从而支持免疫网络学说,可能为我们提供一种新型的抗原来源途径。     

降钙素原的原核表达及单克隆抗体制备

目的:高效表达与纯化可溶性重组人PCT蛋白,制备高灵敏度和高特异性的抗人PCT医用诊断单克隆抗体。方法:大肠杆菌表达重组人PCT蛋白后,利用饱和硫酸铵沉淀和亲和层析方法纯化PCT蛋白后,经质谱、Western blot和间接ELISA法进行性质鉴定和分析重组蛋白的表达与免疫反应性;重组蛋白免疫小鼠,经细胞融合及筛选制备抗PCT单克隆抗体(m Ab)。结果:在大肠杆菌中高效表达了人PCT蛋白;重组人PCT蛋白具有良好的免疫反应性与免疫原性;经筛选获得7株抗PCT单克隆抗体细胞株,经ELISA鉴定,筛选抗体可与PCT抗原有良好的特异性反应。结论:利用重组人PCT蛋白免疫制备了抗人PCT单克隆抗体,为进一步研发PCT快速诊断试剂提供了原料。     

青霉素结合蛋白2a单克隆抗体的研制和初步应用

目的研制青霉素结合蛋白2a(PBP2a)单克隆抗体(Mc Ab),为建立耐甲氧西林金黄色葡萄球菌(MRSA)免疫层析检测方法提供检测用抗体。方法以基因工程抗原r PBP2a免疫BALb/c小鼠,通过常规小鼠B淋巴细胞杂交瘤技术制备单克隆抗体,采用免疫印迹技术(Western blotting)分析单克隆抗体特异性。选取敏感、特异的单克隆抗体进行金标记和硝酸纤维膜包被,建立胶体金免疫层析检测方法。结果共获得11株分泌抗r PBP2a的杂交瘤细胞,其中6株分泌的单克隆抗体能够与天然PBP2a呈阳性反应。用其中2株单克隆抗体建立的PBP2a胶体金免疫层析方法,可在5~20 min内完成检测。结论获得了特异性针对PBP2a蛋白的单克隆抗体,并初步建立了检测PBP2a蛋白的胶体金免疫层析检测方法,为临床快速、简便检测产生PBP2a的细菌提供了检测方法。     

抗人IgG和抗人IgM单克隆抗体的特性鉴定及应用

目的:制备特异性高的抗人Ig G和抗人Ig M单克隆抗体,并应用于临床血清学检测试剂盒,为其提供优质的二抗。方法:以人Ig G和Ig M为抗原,免疫BALB/c小鼠,通过传统杂交瘤融合和筛选技术制备抗人Ig G和抗人Ig M单克隆抗体;经体内诱生法制备腹水并纯化;采用酶联免疫吸附试验(ELISA)和Western印迹进行交叉筛选和特异性鉴定,并对筛选出的单抗进行辣根过氧化物酶(HRP)标记,再与市售的检测病原微生物抗体试剂盒中对应的HRP标记的二抗(抗人Ig G和抗人Ig M)做对比分析。结果:筛选到2株可稳定分泌抗人Ig G单抗和2株抗人Ig M单抗,经交叉反应、Western印迹及对比实验分析,证明这4株单抗效价高、特异性好,比临床试剂盒中的酶标二抗特异性强、敏感度高。结论:获得4株特异性强、敏感度高的抗人Ig G和抗人Ig M单克隆抗体,可为各种病原微生物血清学的检测提供二抗试剂,具有良好的应用价值。     

异色瓢虫卵黄蛋白单克隆抗体的制备及鉴定

【目的】为了能准确地追踪异色瓢虫Harmonia axyridis (Pallas)卵黄原蛋白（vitellogenin, Vg）的合成、转运途径和吸收方式,以及卵黄蛋白（vitellin, Vn）在卵母细胞内的积累及分布情况,本研究对异色瓢虫的Vn进行了单克隆抗体（monoclonal antibody, McAb）的制备。【方法】以异色瓢虫Vn免疫BLAB/C小鼠,应用杂交瘤技术,经过3次亚克隆筛选,制备能稳定分泌抗Vn的单克隆抗体。【结果】实验获得4株能够稳定分泌抗异色瓢虫Vn的单克隆抗体,即5E2, 5E11, 1E9和5H8。其中1E9, 5E11和5E2亚型均为IgG1,5H8亚型为IgM。Western blot免疫印迹分析显示,4株单克隆抗体可以特异性地识别Vn,而与雄虫血淋巴无反应。其中,5E2和1E9可以与异色瓢虫抗原的4个亚基发生较强的免疫反应,结合腹水制备前上清效价检测结果最终选取5E2制备单克隆抗体。5E2单克隆抗体的效价为1∶81 000,SDS-PAGE分析显示5E2重链和轻链的分子量分别为50和27 kD。【结论】本实验成功制备出一株能够稳定分泌抗异色瓢虫Vn的单克隆抗体,为建立酶联免疫吸附试验（ELISA）方法测定其动态变化奠定了基础。     

1组曲霉单克隆抗体的制备与鉴定

目的制备并鉴定一组抗曲霉不同抗原的单克隆抗体。方法采用烟曲霉细胞壁抗原成分、分泌抗原和灭活分生孢子,分别免疫BALB／c小鼠,制备单克隆抗体,免疫荧光法鉴定单克隆抗体与曲霉属和念珠菌属抗原的交叉反应。结果获得29株稳定分泌抗曲霉单抗的杂交瘤细胞株,其中用烟曲霉细胞壁抗原成分免疫获得11株,用分泌抗原免疫获得13株,用孢子免疫获得5株;Ig亚类鉴定,11个克隆株为IgG1亚类,3个克隆株为IgG3,15个克隆株为IgM。免疫荧光法鉴定29株单抗特异性识别烟曲霉细胞壁抗原,与其他曲霉抗原有交叉反应。结论29株单克隆抗体,对于建立侵袭性曲霉感染早期诊断方法、筛选曲霉保护性抗体以及研究抗体保护机制奠定了实验基础。     

番茄花叶病毒单克隆抗体的制备及检测应用

用番茄花叶病毒(ToMV)免疫的BAL B/c鼠脾细胞与SP2/0鼠骨髓瘤细胞融合,经筛选克隆,获得4株能稳定传代并分泌抗ToMV单克隆抗体(Mab)的杂交瘤细胞,其中2株能同时检测ToMV和烟草花叶病毒(TMV),各单克隆抗体腹水ELLSA效价在1∶32 000～1∶1 024 000之间。经TASELISA测定,4株单克隆抗体检测病汁液的稀释度均能达到1∶2 000倍以上。4株单克隆抗体与其他病毒无交叉反应。Westernblot分析表明,其中两株与ToMV176kD的外壳蛋白亚基有特异反应,而另两株无反应,推测它们是针对构象决定簇的抗体。     

Production and characterisation of monoclonal anti-idiotype antibody to Vibrio anguillarum

Seven monoclonal anti-idiotype antibodies (mab2) were raised against mouse monoclonal antibody (mab1) 4A6. Identification of subclass showed that 1H5, 1D1, 2B12 and 2F12 belonged to IgG2b, 2H12 and 1H12 to IgG2a and lE10 to IgG3. The titres of these mab2 ascitic fluids ranged from 1 x 10(-4)-1 x 10(-6). The capacity of the mab2 to inhibit the binding between the corresponding rabbit antiserum and Vibrio anguillarum was investigated with the competitive inhibition ELISA. The results showed that mab2 1D1, 1E10, 1H5 and 1H12 were able to inhibit this binding. Another experiment demonstrated that mab2 1D1, 1E10 and 1H5 might induce Balb/c mice to produce Ab3 and these Ab3 competed the same antigen epitopes with Ab1. These results indicate that mab2 1D1, 1E10 and 1H5 are likely to represent an internal image of V. anguillarum and may thus be described as Ab2-beta anti-idiotype antibodies. In protection experiments, Japanese flounders vaccinated with mab21D1, 1E10 and 1H5 showed significantly enhanced survival from challenge with V. anguillarum. Thus. mab21D1, 1E10 and 1H5 may have use as idiotype vaccines for fish in aquaculture.     

Production of Monoclonal Anti-Idiotype Antibodies Which Mimic an M-Like Protein of Streptococcus equi

Rat monoclonal anti-idiotype antibodies (mAb2) were raised against two mouse monoclonal antibodies (mAb1), 1D10 and 2A6, with specificity for the M-like protein of Streptococcus equi. The capacity of the mAb2 to inhibit the binding between the corresponding mouse mAbl against which the mAb2 were raised and the M-like protein was investigated in an inhibition EIA. One of the ten mAb2 examined, namely 5D1 (anti-mAb1 1D10), was able to inhibit this binding. The mAb2 5D1 bound to the mAb1 1D10 in such a way as to completely inhibit the subsequent binding of the M-like protein antigen to the paratope of the mAb1 1D10. The mAb2 5D1 is likely to represent a true image of the M-like protein antigen and may thus be described as an Ab2β anti-idiotype antibody.     

Fluorescence correlation spectroscopy as a sensitive and useful tool for revealing potential overlaps between the epitopes of monoclonal antibodies on viral particles

Although the enzyme-linked immunosorbent assay (ELISA) is well established for quantitating epitopes on inactivated virions used as vaccines, it is less suited for detecting potential overlaps between the epitopes recognized by different antibodies raised against the virions. We used fluorescent correlation spectroscopy (FCS) to detect the potential overlaps between 3 monoclonal antibodies (mAbs 4B7-1H8-2E10, 1E3-3G4, 4H8-3A12-2D3) selected for their ability to specifically recognize poliovirus type 3. Competition of the Alexa488-labeled mAbs with non-labeled mAbs revealed that mAbs 4B7-1H8-2E10 and 4H8-3A12-2D3 compete strongly for their binding sites on the virions, suggesting an important overlap of their epitopes. This was confirmed by the cryo-electron microscopy (cryo EM) structure of the poliovirus type 3 complexed with the corresponding antigen-binding fragments (Fabs) of the mAbs, which revealed that Fabs 4B7-1H8-2E10 and 4H8-3A12-2D3 epitopes share common amino acids. In contrast, a less efficient competition between mAb 1E3-3G4 and mAb 4H8-3A12-2D3 was observed by FCS, and there was no competition between mAbs 1E3-3G4 and 4B7-1H8-2E10. The Fab 1E3-3G4 epitope was found by cryoEM to be close to but distinct from the epitopes of both Fabs 4H8-3A12-2D3 and 4B7-1H8-2E10. Therefore, the FCS data additionally suggest that mAbs 4H8-3A12-2D3 and 4B7-1H8-2E10 bind in a different orientation to their epitopes, so that only the former sterically clashes with the mAb 1E3-3G4 bound to its epitope. Our results demonstrate that FCS can be a highly sensitive and useful tool for assessing the potential overlap of mAbs on viral particles.     

Induction of delayed-type hypersensitivity responses by monoclonal anti-idiotypic antibodies to tumor cells expressing carcinoembryonic antigen and tumor-associated glycoprotein-72

The use of anti-idiotypic antibodies as immunogens represents one potential approach to active specific immunotherapy of cancer. Two panels of syngeneic monoclonal anti-idiotypic antibodies were generated. One panel was directed against mAb CC49 and the other to mAb COL-1. mAb CC49 recognizes the pancarcinoma antigen (Ag), tumor-associated glycoprotein-72 (TAG-72), and mAb COL-1 recognizes carcinoembryonic antigen (CEA). Seven anti-idiotypic (AI) antibodies (Ab2) designated AI49-1–7 were generated that recognize the variable region of mAb CC49. These mAb were shown to inhibit the interaction of mAb CC49 (Ab1) with TAG-72 (Ag). Five anti-idiotypic antibodies designated CAI-1–5 were also generated to the anti-CEA mAb, COL-1 (Ab1). These Ab2 were shown to inhibit the interaction between COL-1 (Ab1) and CEA (Ag). Immunization of mice, rats, and rabbits with Ab2 directed against CC49 or COL-1 could not elicit specific Ab3 humoral immune responses, i.e., antibody selectively reactive with their respective target antigens. However, immunization of mice with the CC49 anti-idiotypic antibody (Ab2), designated AI49-3, could induce a delayed-type hypersensitivity response (DTH) specific for tumor cells that express TAG-72. Similarly, immunization of mice with an anti-idiotypic antibody directed against COL-1, designated CAI-1, could induce specific DTH cell-mediated immune responses to murine tumor cells that express human CEA on their surface. These results thus demonstrate that while some anti-idiotype mAb may not be potent immunogens in eliciting Ab3 humoral responses, they are capable of eliciting specific cellular immune responses against human carcinoma-associated antigens. This type of mAb may ultimately be useful in active immunotherapy protocols for human carcinoma.Some of the studies described in this paper were in partial fulfillment of requirements for the completion of Dr. Irvine's dissertation at the George Washington University     

Expression, Purification, and In Vivo Administration of a Promising Anti-Idiotypic HIV-1 Vaccine

To date only a few neutralizing antibodies against HIV-1 exist. Since these neutralizing antibodies are only rarely found in sera of HIV-1 infected individuals an active vaccine is required. We recently developed murine anti-idiotypic antibody Ab2/3H6 against monoclonal antibody (mAb) 2F5, which is one of the most prominent neutralizing antibodies. Anti-idiotypic antibody Ab2/3H6 has been partially humanized and expressed as whole immunoglobulin G in Chinese hamster ovary cells in order to minimize the human anti-mouse antibody response. Here we describe the expression, purification, and immunohistochemical characterization of the chimeric Ab2/3H6 Fab fragment, which was finally used beside the whole IgG1 as an antigen for immunization of guinea pigs. The crude sera were screened for specific antibodies against the epitope of mAb 2F5 ELDKWA as well as for reactivity against HIV-1 gp41.     

Monoclonal antibodies against Vibrio anguillarum O2 and Vibrio ordalii identify antigenic differences in lipopolysaccharide O-antigens

Abstract Monoclonal antibodies (mAbs) that recognize distinct species-specific antigenic epitopes in O-antigens from Vibrio anguillarum O2, O2a and certain O2b strains (mAb 7B4) and from Vibrio ordalii strains (mAbs A16 and 7D11) were generated. Western immunoblot analysis using these mAbs revealed that vibrio strains grown in the presence of fresh rainbow trout blood expressed lipopolysaccharide (LPS) with longer (high molecular mass) O-antigens and extracellular capsular layers when compared to strains grown without rainbow trout blood. We also generated mAbs that react with O-antigens from V. anguillarum serotype O1 (mAbs 7B8, 7B5 and 1C3) and serotype O3 (mAbs 13A1 and 14C5) strains. These mAbs provide rapid and accurate diagnostic reagents for serological differentiation of V. ordalii from serotype O2 strains of V. anguillarum , and for serotyping of these pathogenic vibrios.     

Idiotypic analysis of anti-I-Ak monoclonal antibodies. III. T- and B-cell responses to anti-Ia idiotopes are not modulated by syngeneic anti-idiotypic monoclonal antibodies

To investigate whether anti-idiotypic (anti-Id) antibodies activate T cells either directly or indirectly, we examined the ability of syngeneic anti-Id monoclonal antibodies (mAbs) to regulate idiotype (Id) expression, antigen-binding antibody production, and T-cell reactivity to antigen. Our idiotypic system consists of an anti-I-A mAb that carries an infrequently expressed Id. Using three syngeneic anti-Id mAbs (Ab2), we previously defined the idiotype of the 11-5.2.1.9 (11-5) anti-I-Ak mAb. Two of these mAbs, IIID1 and IA2, recognize the same or closely related epitopes on 11-5 and cross react with two additional anti-I-Ak mAbs, 8B and 39J; the third anti-Id mAb, VC6, recognizes a distinct epitope shared by 11-5 and 8B. In the present study, BALB/c (H-2d) mice were primed with varying doses of these anti-Ids and were then boosted with C3H (H-2k) spleen cells. Among 130 such primed mice, the syngeneic anti-Ids when tested at priming doses between 10 ng and 10 micrograms were unable to induce Id production. The priming anti-Id mAbs persisted in the serum of the mice and were detectable as late as 40 days after priming. Ab1 expression was not modulated in BALB/c mice immunized with KLH-coupled Ab2, however, this immunization elicited the production of Ab3 which shared idiotypes with 11-5, 8B, and 39J. BALB/c anti-C3H alloreactive T-cell clones were also not induced by anti-Id priming, nor could they be shown to bind directly to the three Ab2 used. Nevertheless, the proliferative response of one anti-I-Ak specific T-cell clone that recognizes the same epitope as 11-5, 8B, and 39J, was inhibited by the IIID1 and IA2 Ab2. Thus, a T cell can express an idiotype shared by a B cell, but the linked recognition of an Id-associated carrier determinant(s) by an alloreactive T cell is required to elicit an anti-Id antibody response. These results favor the possibility that the activation of T cells is not dependent upon their ability to bind to anti-Id, but rather on their capacity to respond to epitopes of Id-anti-Id antigen-antibody complexes formed on B cells.     

Strain-related differences in antibody-mediated changes in gene expression are associated with differences in capsule and location of binding

We recently established that antibody (Ab)-binding can induce gene expression changes in a serotype A strain (H99) of the pathogenic yeast, Cryptococcus neoformans. That study showed that monoclonal antibodies (mAbs) differing in epitope specificity and protective efficacy elicited differences in gene expression. Because many mAbs bind to serotypes A and D strains differently, we now investigate the binding of one mAb to two strains representing these serotypes. Cells of the serotype A strain H99 and the serotype D strain 24067 were incubated with near saturating concentrations of the IgG1 capsule-binding mAb 18B7 or MOPC, an irrelevant mAb matched control. Comparative immunofluorescence analysis of mAb 18B7 binding revealed that it bound closer to the cell wall in H99 than 24067, where it was associated with decreased or increased cell diameter, respectively. A comparison of encapsulated cell compressibility showed that strain 24067 was more compressible than that of strain H99. RNA was extracted and used for gene expression analysis using the C. neoformans JEC21 genomic microarray. After 1h incubation with mAb 18B7, there were just 2 gene expression changes observed with strain 24067 or strain JEC21, unlike the 43 seen with strain H99. After 4h incubation with mAb 18B7, there were 14 and 140 gene expression changes observed with strain 24067 and JEC21, respectively. Thus, C. neoformans strains differ both in the response and the time of response to mAb binding and these differences may reflect differences in the location of Ab binding, Ab-mediated changes in cell diameter and compressibility of the capsular polysaccharide.     

Recognition of two Dermatophagoides pteronyssinus-specific epitopes on antigen P1 by using monoclonal antibodies: binding to each epitope can be inhibited by serum from dust mite-allergic patients

Monoclonal antibodies were raised against Antigen P1, the major allergen of the house dust mite (Dermatophagoides pteronyssinus). The majority were Antigen P1 specific, isotype IgG1, and did not react with a comparable D. farinae allergen. These antibodies bound 38 to 50% of 125I Antigen P1 in antigen-binding assays (titer greater than or equal to 1/1,000,000), and the quantities of IgG antibody in ascites were 2 to 4 logs greater than those in polyclonal mouse antiserum or in serum from a mite-allergic patient. Two IgM antibodies showed weak binding to Antigen P1 but reacted strongly with D. pteronyssinus in enzyme immunoassay (titer greater than or equal to 1/100,000). Assessments of the specificity of the IgG antibodies by using two inhibition radioimmunoassays suggested that they were directed against two different epitopes. Antibodies 10B9 F6 and 5H8 C12 were purified by preparative isoelectric focusing (isoelectric points of pI 6.25 and 7.4, respectively) and radiolabeled with 125I. Cross-inhibition experiments, using ascites dilutions to inhibit binding of each radiolabeled antibody to Antigen P1, confirmed that these antibodies recognized two distinct epitopes. Analysis of antibodies from 39 clones/hybrids showed that the majority were directed against the same epitopes as either 10B9 F6 or 5H8 C12 (3 out of 39 [8%] and 29 out of 39 [74%], respectively). None of the monoclonal antibodies significantly inhibited (greater than 10%) human IgE binding to Antigen P1 in the radioallergosorbent test. However, 12 of 14 sera from mite allergic patients inhibited binding by the monoclonal antibodies. One serum from a mite-allergic patient inhibited binding of both 10B9 F6 and 5H8 C12 by greater than 85% and showed parallel inhibition curves. The results suggest that these monoclonal antibodies could be used to assay Antigen P1 in both D. pteronyssinus and house dust extracts. It should also be possible to use monoclonal antibodies in inhibition assays to define the antigenic/allergenic determinants recognized by human IgG and IgE antibodies on this mite allergen.     

Characterization of the antibody response against NeuGcGM3 ganglioside elicited in non-small cell lung cancer patients immunized with an anti-idiotype antibody

1E10 mAb is an anti-Id murine mAb (Ab2 mAb) specific for an Ab1 mAb that reacts with NeuGc-containing gangliosides, sulfatides, and Ags expressed in some human tumors. In preclinical studies, this Ab2 Ab was able to mimic NeuGc-containing gangliosides only in animals lacking expression of these Ags in normal tissues. In this study, we report on the immune responses elicited in 20 non-small cell lung cancer patients treated with 1 mg of aluminum hydroxide-precipitated 1E10 mAb. In the hyperimmune sera from 16 of 20 patients, a strong specific Ab response of both IgM and IgG isotypes against NeuGcGM3 ganglioside was observed. Patient immune sera were able to induce complement-independent cell death of NeuGcGM3-expressing X63 murine myeloma target cells. Significant immunoreactivity to NeuGcGM3 was still detected after the complete abrogation of the reactivity against 1E10 mAb by the adsorption of patient sera with this Ab. We hypothesize that Id(-)Ag(+) Abs could reflect the activation of an autologous idiotypic cascade into the patients. Both Id(+)Ag(+) and Id(-)Ag(+) fractions were separated by affinity chromatography and characterized. Although IgG isotype Abs were found in both fractions, IgM isotype Abs were found only in the Id(-)Ag(+) fraction. Both Id(+)Ag(+) and Id(-)Ag(+) Abs were able to specifically recognize and induce cell death in NeuGcGM3-expressing X63 myeloma target cells. Patients that developed IgG and/or IgM Abs against NeuGcGM3 showed longer median survival times.