C3 complement polymorphism in patients suffering from obstructive chronic bronchopneumopathy in Tunisia

We analysed the C3*S and C3*F polymorphism of the third component of the complement (C3), first at the protein level by the electrophoresis of the plasma on agarose gel and second on the gene level by the ARMS PCR technique. We determined the phenotypic and genotypic frequencies of the C3 on a sample of 90 patients suffering from the obstructive chronic bronchopneumopathy (OCBP) disease. Comparisons have been done with frequencies observed on a control sample of 437 healthy individuals from the Tunisian population in order to establish a putative correlation between the polymorphism studied and the disease. Frequencies of the C3*S and C3*F alleles in OCBP patients are 0,788 and 0,212 respectively. They are not significantly different from those observed in control sample (0,834 and 0,152 respectively). Therefore, no correlation is observed between the C3 polymorphism and the risk of developing the OCBP disease.     

Complement polymorphism in Greece

The polymorphisms of the complement components C2, C3, C4 and BF have been studied in a sample of 166 unrelated individuals from Northern Greece. The C3*F and BF*F allele frequencies of Greeks are within the range of frequencies reported from Europe. A single individual with a rare heterozygote variant C2C/C2A was found in Greeks. This C2*A allele was found for the first time in European Caucasoids. For the C4 system six different alleles were found at both C4A and C4B loci. There were a low frequency of the null alleles at the C4A locus and a relatively high incidence of gene duplications in this system.     

A DNA restriction fragment length polymorphism in the complement region of the human MHC shows an absolute correlation with polymorphism of complement factor B(Bf) defined by isoelectric focusing

The gene coding for properdin factor Bf is located in the human major histocompatibility complex and is closely linked to the genes coding for the complement components C2 and C4. Recently, by Southern blotting techniques, a restriction fragment length polymorphism was identified using the endonuclease Taq I, which subdivides haplotypes carrying the F allele of factor Bf. The F allotype has also been subdivided at the protein level by isoelectric focusing into two subtypes Fa and Fb. We have investigated the DNA of 41 healthy unrelated individuals with known BfF subtypes using the 2.3 kb factor Bf cDNA probe to determine if there is any correlation between the Taq I polymorphism and F subtype. We have found that in 23 individuals who carried the Fb subtype a 6.6 kb Taq I fragment was present. The remaining 18 individuals carried the Fa subtype and showed only the 4.5 kb Taq I fragment on Southern blotting (P = 10(-12). This striking correlation (r = 1) between the Fb protein and DNA polymorphism is surprising especially as the 4.5 kb and 6.6 kb Taq I fragments overlap the Bf and C2 genes and the polymorphic Taq I site is located within the C2 gene.     

Complement C4A, C4B and BF haplotypes in Koreans

Specific alleles at C4A, C4B and BF loci occur in populations and are inherited in complotypes, which are linked with particular HLA haplotypes. Considerable differences in complement allele and complotype frequencies have been observed among various ethnic groups. In the present study, 109 Korean families were analyzed for complement and complotype polymorphism. Thirty-four different complotypes were detected: the most common was BF*S-C4A*3-C4B*1 (S31) with a frequency of 42.2%, followed by S42 (14.3%) and F31 (13.8%). Three complotypes, S42, F31, and FQ01, showed positive linkage disequilibrium. Some of the complotypes were linked with characteristic HLA haplotypes. Two complotypes carrying duplicated C4A genes, S3+31 (BF*S-C4A*3-C4A*3-C4B*1) and S3+2Q0(BF*S-C4A*3-C4A*2-C4B*Q0), were exclusively associated with HLA-A24-Cw7-B7-DR1-DQ1 and A24-CBL-B52-DR15-DQ1 haplotypes, respectively. Twelve families showed recombinant haplotypes, nine in the class I region, three between the HLA-B and HLA-DR loci, and none in the class III region. Maternal recombination occurred twice as frequently as paternal. The results obtained in this study represent the frequencies of complotypes and extended HLA haplotypes of well-defined Koreans, based on a family study.     

PON2基因C311S、G148A多态性与脑卒中关系的研究

目的探讨对氧磷酶2（paraoxonase2,PON2）基因多态性与脑卒中的关系。方法用聚合酶链反应-限制性片段长度多态性分析法分别检测PON2基因C311S、G148A多态性在脑出血组（150例）、脑梗死组（180例）和正常对照组（120名）的基因频率。结果发现中国湖南地区人群存在PON2基因C311S、G148A多态性,在正常对照组中等位基因频率分别是S/C0.77/0.23,A/G0.43/0.57。脑出血组、脑梗死组患者PON2基因的等位基因频率与正常对照组相比差异无统计学意义（P〉0.05）。结论PON2基因多态性可能与中国湖南汉族人群脑卒中发病无关,C/S、G/A等位基因可能不是中国湖南地区汉族人群脑卒中发病的独立危险因素。     

卵磷脂胆固醇酰基转移酶基因单核苷酸多态性与冠心病脂代谢易感性的关联研究

目的：检测卵磷脂胆固醇酰基转移酶（lecithin cholesterol acyltransferase,LCAT）基因3个编码区单核苷酸多态位点在中国人群中的分布频率，并初步探讨它们与脂代谢和冠状动脉粥样硬化性心脏病（coronary atherosclerotic heart disease,CHD）易感性的关系。方法：采用聚合酶链反应－限制性片段长度多态性方法，分析209名正常人和203例CHD患者中608C／T、911T／C和1188C／T（参照序列：NM_000229）3个位点的多态性。结果：608C和608T等位基因频率分布符合Hardy-Weinberg平衡。CHD患者组608T频率显著低于正常人群（P＝0．034）。与无608T CHD患者相比，具有608T的CHD患者的血浆高密度脂蛋白胆固醇显著升高（P＝0．015）。911T／C和1188C/T在两组中均未检出。结论：LCAT基因608T等位基因与CHD患者较高的血浆高密度脂蛋白胆固醇水平相关联，可能与中国人CHD相关。911T／C和1188C／T在中国人群中非常罕见。     

葡萄糖醛酸转移酶1F基因多态性及与肝癌易感性研究

目的 探讨葡萄糖醛酸转移酶1F（UDP－glucuronosyltransferase 1F,UGT1F）基因的多态性及其与肝癌的关系。方法 应用聚合酶链反应、变性梯度凝胶电泳、单链构象多态和DNA测序技术，对84例肝癌患者和144名健康对照的UGT1F基因的多态性进行了研究。结果 在第1外显子和第2内含子发现3个新的单核苷酸多态。即第232位核苷酸T→G颠换，第528位核苷酸A→G转换和第376位核苷酸A→G转移。另外，754位点多态在我们的研究中得到了证实。分析病例组和对照组4个位点等位基因及基因型频率的分布，病例组UGT1F754位点G／G基因型频率（13.10%）和G等位基因频率（29.17%）均显著高于对照组（2.78%和19.44%）。其它位点，两组差异无显著性。结论 UGT1F基因的第2－5外显子高度保守，而第1外显子则呈高度多态。其754位点多态可能与肝癌有关。     

Studies on the association of Fc gamma receptor IIA,IIB, IIIA and IIIB polymorphisms with rheumatoid arthritis in the Japanese: evidence for a genetic interaction between HLA-DRB1 and FCGR3A

We recently detected a new single nucleotide polymorphism of FcgammaRIIB gene, which alters an amino acid within the transmembrane domain from Ile to Thr (I232T), and its association with SLE in the Japanese. This study was performed to examine whether FCGR2B-I232T was associated with susceptibility to rheumatoid arthritis in the Japanese. At the same time, FCGR2A, 3A and 3B polymorphisms were also examined. Genotyping of FCGR2B-I232T, FCGR2A-H131R, FCGR3A-F176V and FCGR3B-NA1/2 polymorphisms were performed using genomic DNA. Association with RA was analyzed in 382 Japanese patients with RA and 303 healthy individuals using a case-control approach. In addition, the same groups of patients and controls were genotyped for HLA-DRB1 to examine possible interaction with FCGR genes. Significantly different distribution of genotype, allele carrier and allele frequencies was not observed between patients with RA and healthy individuals in any of the four polymorphisms. When the subjects were stratified according to the carriage of HLA-DRB1 shared epitope (SE), significant increase of FCGR3A-176F/F genotype was observed in SE positive patients compared with SE positive healthy individuals (P=0.009, P(corr)=0.07). In conclusion, FCGR3A-176F/F genotype was considered to confer risk through genetic interaction with HLA-DRB1 SE.     

白细胞介素-18基因多态性与广西壮族系统性红斑狼疮的遗传易感性

目的 探讨白细胞介素-18(interleukin 18,IL-18)基因单核苷酸多态性与广西壮族系统性红斑狼疮(systematic lupus erythematosus,SLE)易感性之间的关系.方法 以115例SLE患者和160名健康对照者为研究对象,应用聚合酶链反应-限制性片段长度多态性和DNA测序的方法对IL-18基因-137G/C、-607C/A单核苷酸多态性进行基因分型.结果 IL-18基因-137G/C多态性在SLE组和正常人群中的分布差异无统计学意义(P>0.05),而IL-18基因-607C/A多态性在两组人群中的分布差异有统计学意义(P<0.05),等位基因频率的相对风险分析发现,-607 C等位基因携带者患系统性红斑狼疮的风险是-607A等位基因的1.619倍(OR=1.619,95%CI:1.150-2.281).联合基因型分析发现,IL-18的-137G/-607C等位基因频率在SLE组中显著高于对照组(P<0.05).-137G/-607C等位基因携带者显著增加了SLE的发病风险(OR=1.484,95%CI:1.056-2.087).结论 IL-18基因-607C/A多态性与SLE的发病具有相关性,其中-607 C等位基因可能是SLE的遗传易感基因.     

Lack of association of alpha-1 antichymotrypsin gene polymorphism with PR3-ANCA and MPO-ANCA associated vasculitis

In patients with PR3-ANCA associated vasculitides the carrier frequency of alpha1-antitrypsin (AAT) deficiency allele PI*Z is increased and linkage disequilibrium between polymorphic markers within a cluster of serine protease inhibitor (serpin) genes, including AAT gene, at chromosome 14q32.1 has been described. A1-antichymotrypsin (AACT), part of an extended serpin gene cluster, was discussed to contribute to PR3-ANCA associated vasculitis formation. To analyse, if an AACT gene polymorphism within the signal peptide sequence is associatedwith antineutrophil cytoplasm autoantibodies (ANCA) vasculitis allelic frequencies of AACT polymorphism were analysed in 128 control persons, 79 PR3-ANCA, and 30 MPO-ANCA patients. In MPO-ANCA patients also phenotyping of AAT was performed as well as frequency and linkage analysis of simple tandem repeat polymorphisms in the genes of cortisol-binding globulin, AAT, protein C inhibitor, and three extragenic markers (S48, S55, S51) of the gene cluster. Allelic frequencies of the AACT polymorphism did not differ between controls and vasculitis patients. In the MPO-ANCA group no patient expressed the Pi*Z defective allele of AAT and the allelic frequencies of polymorphic markers within the serpin gene cluster did not differ from those of the controls. Strong linkage disequilibrium was detected in MPO-ANCA patients neither. Therefore, we can not support the hypothesis that AACT polymorphism contributes to the pathogenesis of PR3-ANCA vasculitis. Nor is it probable that any factor, coded by the serpin gene cluster, contributes to MPO-ANCA vasculitis.     

Lack of Association of Alpha-1 Antichymotrypsin Gene Polymorphism with PR3-ANCA and MPO-ANCA Associated Vasculitis

In patients with PR3-ANCA associated vasculitides the carrier frequency of &#102 1-antitrypsin (AAT) deficiency allele PI*Z is increased and linkage disequilibrium between polymorphic markers within a cluster of serine protease inhibitor (serpin) genes, including AAT gene, at chromosome 14q32.1 has been described. A 1 -antichymotrypsin (AACT), part of an extended serpin gene cluster, was discussed to contribute to PR3-ANCA associated vasculitis formation. To analyse, if an AACT gene polymorphism within the signal peptide sequence is associated with antineutrophil cytoplasm autoantibodies (ANCA) vasculitis allelic frequencies of AACT polymorphism were analysed in 128 control persons, 79 PR3-ANCA, and 30 MPO-ANCA patients. In MPO-ANCA patients also phenotyping of AAT was performed as well as frequency and linkage analysis of simple tandem repeat polymorphisms in the genes of cortisol-binding globulin, AAT, protein C inhibitor, and three extragenic markers (S48, S55, S51) of the gene cluster. Allelic frequencies of the AACT polymorphism did not differ between controls and vasculitis patients. In the MPO-ANCA group no patient expressed the Pi*Z defective allele of AAT and the allelic frequencies of polymorphic markers within the serpin gene cluster did not differ from those of the controls. Strong linkage disequilibrium was detected in MPO-ANCA patients neither. Therefore, we can not support the hypothesis that AACT polymorphism contributes to the pathogenesis of PR3-ANCA vasculitis. Nor is it probable that any factor, coded by the serpin gene cluster, contributes to MPO-ANCA vasculitis.     

GENOMIC ANALYSIS OF THE F SUBTYPES OF HUMAN COMPLEMENT FACTOR B

Factor B of human complement is encoded within the Major Histocompatibility Complex (MHC) and is polymorphic, with up to 30 alleles defined by electrophoretic mobility. One of the most common alleles, BF*F, is subdivided into the FA and FB subtypes, which differ at the gene level by non-synonymous base substitutions in the seventh codon. We have found at this position a new restriction site polymorphism, as a Bsl I site absent from the FB allele. Using this restriction polymorphism, we have developed a method for BF F subtype determination, based on amplification by polymerase chain reaction of the 5’ end of the BF gene, and digestion with Bsl I. This new method has been applied to a panel of 29 selected BF F individuals. A single strand DNA conformation analysis of the same region of the gene allowed us to confirm the above DNA-based BF F subtyping. During this study, two BF*F1 alleles showed discrepancies between protein and DNA typing, which were confirmed by our sequencing data. These were identical, in the 5’ region, to BF*S and BF*FB genes, respectively. In a comparison with two protein subtyping methods, identical results were found for only one third of the selected samples. The conflicting results may arise, in part, from previously undescribed molecular heterogeneity within BF F subtypes, or from the presence of a null allele. Our new method allows RF*F subtyping to be used with confidence in the definition of disease-associated MHC haplotypes.     

FKBP6基因278C/A单核苷酸多态性与原发无精症相关研究

目的对FKBP6基因第3、4外显子进行突变和多态性筛查,研究第3外显子278C/A位点及第2内含子C/T位点(rs7797242)在无精症患者和正常男性中的多态性,初步探讨与原发无精症的相关性。方法采用变性高效液相色谱和聚合酶链反应-限制性片段长度多态性方法,对第3、4外显子进行突变和多态性筛查,对177例无精症患者和231名正常男性的278C/A和C/T(rs7797242)多态性进行基因分型。结果278C和278A等位基因频率符合Hardy-Weinberg平衡。无精症患者278A显著低于正常对照,差异有统计学意义(P<0.05)。C/T多态性在两组中均未检出,第3、4外显子未筛查到新的变异。结论278A等位基因可能与原发无精症相关。C/T(rs7797242)及370G/A,430G/C,467T/C,468G/A在中国人群中非常罕见。     

Polymorphism of interleukin-18 promoter influences the onset of kidney graft function after transplantation

It has been well recognized that the promoter polymorphisms of interleukin-18 (IL-18) influence the level of cytokine expression. In our previously published data, we showed constitutive IL-18 expression in the epithelium of renal distal tubules in patients after kidney transplantation and significantly elevated IL-18 expression during acute rejection. In this study, we evaluated the clinical significance of two functional promoter polymorphisms of the IL-18 gene at positions -607 A/C (rs1946518) and -137 C/G (rs187238) in patients after kidney transplantation and looked for associations with the onset of graft function and the incidence of rejection episodes. Promoter polymorphisms in 124 patients and 103 unrelated controls were evaluated by sequence-specific primer polymerase chain reaction and the allele, genotype and haplotype frequencies were statistically correlated. We found a statistically different distribution of the allele frequency of -607 A/C polymorphism between patients with immediate or delayed onset of kidney graft function. Data showed that the C allele, which contributes to higher IL-18 expression, is more frequent in patients with delayed onset of function (P = 0.03, odds ratio = 1.93; 95% confidence interval = 1.15-3.25). A/C single nucleotide polymorphisms of the IL-18 promoter at position -607 may influence the onset of early kidney allograft function.     

Epstein-Barr virus transformed B cell lines derived from patients with systemic lupus erythematosus produce a nephritic factor of the classical complement pathway

Nephritic factor of the classical complement pathway (C4NeF) is an IgG antibody which stabilizes the C3 convertase (C4b2a) and has been detected in sera from patients with systemic lupus erythematosus (SLE) and acute postinfectious glomerulonephritis. In order to study the production of nephritic factor (NeF), mononuclear cells were isolated from the peripheral blood of patients with SLE and infected with Epstein-Barr virus (EBV) to establish active B lymphocyte cell lines. Supernatants from 15 established B cell lines, as well as from 10 B cell lines established from normal individuals, were investigated for their ability to conserve the classical and the alternative pathway C3 convertases as assessed by EAC3bBb and EAC14b2a stabilizing assays. Supernatants from 2 of 15 B cell lines from patients with SLE, but none from normal individuals, stabilized the classical C3 convertase without having any effect on the alternative pathway C3 convertase. Using anti-human Ig affinity chromatography, we showed that C4NeF activity resided in the IgG fraction; the IgG fraction containing C4NeF activity bound to the C4b2a complex, but not to C4b alone. On gel electrophoresis, following reduction, the heavy chains were slightly heavier than the heavy chains of normal IgG. We were able to isolate C4NeF from the sera of the 2 patients with SLE from whom the positive supernatants were derived, but were unable to detect any C4NeF activity in the sera of the other 13 patients and the 10 normal individuals. Serum and B cell line supernatant-derived C4NeF exhibited comparable characteristics. We conclude that C4NeF produced in vitro by EBV-transformed B cell lines derived from patients with SLE is functionally similar to the conventional C4NeF in serum. These studies confirm the production of autoantibodies by B cells with the ability to stabilize the classical pathway C3 convertase in certain patients with SLE; stabilization of the C4b2a enzyme in these patients is an apparent mechanism for the development of hypocomplementemia. Finally, preparation of homogeneous C4NeF in vitro should improve our understanding of the role of autoantibodies in complement metabolic disturbances in autoimmune diseases.     

中国广西人白细胞介素-21基因rs2221903 T/C遗传多态性研究

目的:了解白细胞介素-21(IL-21)基因单核苷酸多态性(SNP)各等位基因及基因型在中国广西地区人群中的分布频率,比较其在不同种族间分布的差异。方法:采用单碱基延伸的PCR技术和DNA测序法检测199例中国广西人的IL-21基因rs2221903 T/C多态性,并结合人类基因组计划(Hapmap)公布的欧洲人、非洲人、日本人和中国北京人的SNP分型数据,比较分析广西人与其他种族人群的基因型及等位基因分布频率的差异。结果:广西人IL-21基因型TT、TC和CC频率分别为75.38%、23.62%和1.01%;等位基因T、C频率分别为87.19%和12.81%。其基因型频率在男女组间比较差异无统计学意义(P>0.05)。广西人与欧洲和非洲人群比较,IL-21基因多态性分布频率差异均有统计学意义(P<0.05);而与日本人和中国北京人比较差异无统计学意义(P>0.05)。结论:在中国广西人群中存在IL-21基因多态性,且与其他种族人群比较存在显著性差异,这种差异对于人类学的研究可能起重要的作用。     

Lack of association between polymorphisms in C4b‐binding protein and atypical haemolytic uraemic syndrome in the Spanish population

Dysregulation of the alternative pathway of complement activation, caused by mutations or polymorphisms in the genes encoding factor H, membrane co‐factor protein, factor I or factor B, is associated strongly with predisposition to atypical haemolytic uraemic syndrome (aHUS). C4b‐binding protein (C4BP), a major regulator of the classical pathway of complement activation, also has capacity to regulate the alternative pathway. Interestingly, the C4BP polymorphism p.Arg240His has been associated recently with predisposition to aHUS and the risk allele His240 showed decreased capacity to regulate the alternative pathway. Identification of novel aHUS predisposition factors has important implications for diagnosis and treatment in a significant number of aHUS patients; thus, we sought to replicate these association studies in an independent cohort of aHUS patients. In this study we show that the C4BP His240 allele corresponds to the C4BP*2 allele identified previously by isoelectric focusing in heterozygosis in 1·9–3·7% of unrelated Caucasians. Crucially, we found no differences between 102 unrelated Spanish aHUS patients and 128 healthy age‐matched Spanish controls for the frequency of carriers of the His240 C4BP allele. This did not support an association between the p.Arg240His C4BP polymorphism and predisposition to aHUS in the Spanish population. In a similar study, we also failed to sustain an association between C4BP polymorphisms and predisposition to age‐related macular degeneration, another disorder which is associated strongly with polymorphisms in factor H, and is thought to involve alternative pathway dysregulation.     

Identification of novel single nucleotide polymorphisms within the NOTCH4 gene and determination of association with MHC alleles.

Mapping of disease susceptibility loci within the MHC has been partly hampered by the high degree of polymorphism of the HLA genes and the high level of linkage disequilibrium (LD) between markers within the MHC region. It is therefore important to identify new markers and determine the level of LD between HLA alleles and non-HLA genes. The NOTCH4 gene lies at the centromeric end of the MHC class III region, approximately 335 kb telomeric of the DRB1 locus. The encoded protein is an oncogene that is important in regulating vascular development and remodelling. A recent report has linked polymorphisms within NOTCH4 with risk of developing schizophrenia. We have investigated if coding polymorphisms exist within this gene and have identified three single nucleotide polymorphisms; a synonomous T to C transition at +1297 (HGBASE accession number SNP000064386), a synonomous A to G transition at +3061 (SNP000064387) and an A to G transition at +3063 which results in a replacement of glycine with aspartic acid at amino acid 279 (SNP000064388). The allele frequencies of +1297T, +3061A and +3063G were 0.65, 0.66 and 0.66, respectively. Linkage disequilibrium was detected both between these markers and with MHC alleles. These findings can be used in the fine mapping of disease susceptibility alleles within the MHC.     

MMP-2和TIMP-2基因多态性与子宫内膜异位症和子宫腺肌病发病风险的关联研究

目的 探讨基质金属蛋白酶-2(matrix metalloproteinase-2,MMP-2)和金属蛋白酶组织抑制剂-2(tissue inhibitor of metalloproteinase-2,TIMP-2)基因启动子区单核苷酸多态性与子宫内膜异位症和子宫腺肌病发病风险的关系.方法 采用PCR-限制性片段长度多态方法检测298例子宫内膜异位症患者(内异症组)、180例子宫腺肌病患者(腺肌病组)和324名对照妇女(对照组)MMP-2和TIMP-2基因型频率的分布.结果 MMP-2-1306C/T多态的基因型和等位基因频率分布在子宫内膜异位症组与对照组间差异无统计学意义(P＞0.05);但在腺肌病组和对照组间MMP-2-1306C/T多态的基因型和等位基因频率分布均有明显的差异(P＜0.05);与CT+TT基因型相比,CC基因型明显增加腺肌病的发病风险,OR值为1.83(95%CI:1.13～2.96).MMP-2-735C/T多态的基因型和等位基因频率分布在3组间均未发现明显差异(P＞0.05);统计学分析显示MMP-2基因的2个多态性位点间存在着连锁不平衡(D'=0.74),但4种单倍型频率在3组之间分布差异无统计学意义(P＞0.05).TIMP-2-418G/C多态的等位基因频率分布在3组间差异无统计学意义(P＞0.05),但CC基因型频率在子宫内膜异位症组患者中为0.7%,与对照组(3.7%)比较,差异有统计学意义(P＜0.05).结论 MMP-2-1306C/T多态C等位基因的存在可明显增加腺肌病的发病风险,但与子宫内膜异位症的发病风险无关;MMP-2-735C/T和77MP-2-418G/C多态与子宫内膜异位症和腺肌病的发病风险无明显关联.     

Human polyclonal and monoclonal IgG and IgM complement 3 nephritic factors: evidence for idiotypic commonality

Complement 3 nephritic factors (C3NeF) were isolated from the sera of patients with membranoproliferative glomerulonephritis (MPGN) and the supernatants of pokeweed mitogen-stimulated mononuclear cells from patients with MPGN. Three human monoclonal C3NeF antibodies (two IgGs, CK and PH, and one IgM, K3C4) were established. Using an exhaustive series of affinity columns, we isolated anti-C3NeF idiotypic antibodies (anti-IdNeF) (three from normal and two from patient sera). Anti-IdNeF preparations bound to F(ab')2-NeF and prevented its ability to stabilize C3bBb convertase. We have used the above reagents to address questions on the genesis and the diversity of C3NeF antibodies. The following results were obtained: All anti-IdNeF preparations bound to C3NeF isolated from patient sera, cell culture supernatants, and IgG and IgM monoclonal C3NeF. None of the monoclonal C3NeF bound to an extensive battery of common antigens, including Fc portion of IgG, TNP, beta-galactosidase, DNA, and bacterial products. These data indicate that C3NeF express one common idiotype and that these antibodies are not raised in response to an obvious antigen.