SLE血清中抗-DNA抗体分离和性质的研究

本文用国产高分子树脂(T)接枝小牛胸腺DNA,通过亲合层析从系统性红斑狼疮SLE患者血清中纯化出抗-ds DNA抗体和抗-ss DNA抗体。酶联免疫吸附分析(ELISA)的研究表明:SLE抗-DNA抗体和DNA结合的差异性很大,是高度非均一性的。抗-ss DNA抗体不仅组成成分比抗-ds DNA抗体复杂,ss DNA/抗-ssDNA亲合能力也明显高于ds DNA/抗-ds DNA。纯化的抗-DNA抗体以IgG类抗体占主导,同时也有其它类型抗体存在(例如IgM等)。抗-ds DNA抗体有较抗-ss DNA抗体高的IgG含量(两者的IgG/IgM分别是7.0和4.0),说明IgG抗-DNA抗体更倾向于同dsDNA结合。     

内蒙地区发热患者血清中冠状病毒抗体的检测

目的分析内蒙地区发热患者中冠状病毒的感染情况。方法以SARS冠状病毒感染Vero细胞涂片为冠状病毒抗原片,用间接免疫荧光法分别检测55例发热患者和68例正常人血清中冠状病毒的IgG、IgM抗体。结果发热患者血清中冠状病毒IgG抗体和IgM抗体阳性率分别为29.1%(16/55)和10.9%(6/55),而正常人血清中只检测到2.9%(2/68)的IgG抗体,且未检测到IgM抗体,2组患者的IgG和IgM抗体阳性率比较差异均有显著性;随机选取7例患者的IgG阳性血清进行SRAS冠状病毒的特异性抗体封闭实验,结果有6例血清仍为阳性,有1例血清转为阴性,说明冠状病毒IgG抗体阳性血清中85.7%为普通冠状病毒特异性,14.3%为SARS冠状病毒特异性。结论普通冠状病毒是内蒙地区发热患者的主要病原体之一,部分患者还存在SARS冠状病毒的既往感染。     

系统性红斑狼疮(SLE)患者血清免疫复合物中DNA的提取及电镜观察

从活动期SLE患者血清DNA/抗-DNA免疫复合物中分离DNA,用电镜观察结果表明:这些DNA是很不均质的双链片段。它们的分子量范围很宽,镜下可见的最小片段长553A(约150bp),最大片段长10431A(约2800bp),多数DNA片段长约200—400bp,与正常对照相比较有明显区别。另外,还观察到具有单链末端的双链DNA片段。     

SLE患者血清中SARS—CoV抗体阳性原因分析

为了探讨严重急性呼吸综合征(SARS)冠状病毒(SARS—CoV)抗体测定在系统性红斑狼疮(SLE)患者中的假阳性问题,应用酶联免疫吸附试验(ELISA)和荧光定量RT—PCR技术检测了66例正常对照和31例SLE患者血清中SARS—CoV抗体的阳性率。结果,66例正常对照中,IgM抗体均阴性,IgG抗体的阳性率为3．0％(2／66);31例SLE患者中,IgM抗体和IgG抗体阳性率分别为29％(9／31)和58．1％(18／31),IgG抗体和IgM抗体同时阳性为22．6％(7／31)。经RT—PCR检测,上述阳性病例均为阴性。结论：用非纯化抗原制备的ELISA试剂盒测定SLE患者的SARS—COV抗体,可能出现假阳性,两种抗体同时测定可降低诊断的假阳性率,提高诊断的特异性。在SLE患者中出现假阳性的原因可能与包被的抗原有关。     

SLE患者血清中SARS-CoV抗体阳性原因分析

为了探讨严重急性呼吸综合征(SARS)冠状病毒(SARS-CoV)抗体测定在系统性红斑狼疮(SLE)患者中的假阳性问题,应用酶联免疫吸附试验(ELISA)和荧光定量RT-PCR技术检测了66例正常对照和31例SLE患者血清中SARS-CoV抗体的阳性率。结果,66例正常对照中,IgM抗体均阴性,IgG抗体的阳性率为3.0%(2/66);31例SLE患者中,IgM抗体和IgG抗体阳性率分别为29%(9/31)和58.1%(18/31),IgG抗体和IgM抗体同时阳性为22.6%(7/31)。经RTPCR检测,上述阳性病例均为阴性。结论:用非纯化抗原制备的ELISA试剂盒测定SLE患者的SARS-CoV抗体,可能出现假阳性,两种抗体同时测定可降低诊断的假阳性率,提高诊断的特异性。在SLE患者中出现假阳性的原因可能与包被的抗原有关。     

质粒DNA抗原芯片检测抗双链DNA抗体的初步研究

目的:建立以质粒DNA作为抗原的检测血清中抗双链DNA(dsDNA)抗体的芯片方法,并与酶联免疫吸附实验比较,初步探讨用芯片法检测抗dsDNA抗体的临床价值。方法:将原核表达载体质粒pcDNAⅡ用质粒DNA快速抽提试剂盒提取纯化DNA后按1∶2稀释,用点样仪点在经3-氨丙基三乙氧基硅烷(APES)修饰的玻片上,温孵后用含有1%小牛血清白蛋白和2.5%蔗糖的PBST封闭,以Cy3标记的人IgG为二抗,建立检测dsDNA抗体的芯片方法,并与德国欧蒙公司生产的抗双链DNA检测ELISA试剂盒做比较,对包括58例系统性红斑狼疮(SLE)、25例干燥综合征(SS)、10例皮肌炎(DM)和7例类风湿关节炎(RA)在内的病人和60例健康人对照进行了抗dsDNA的对比检测。结果:对阳性标本的检测,与现用常规检测方法ELISA相比,芯片检测抗dsDNA的灵敏度为91.3%,特异度为90.7%,阳性预测值为89.3%,阴性预测值为92.5%;对健康对照的检测,2种方法均为阴性,符合率为100%。结论:与ELISA相比,用质粒DNA作为抗原建立的芯片方法的灵敏度和特异度较高,为今后建立同时检测多个自身抗体的芯片奠定了基础。     

41例新型冠状病毒肺炎患者血清抗体检测分析

目的比较新型冠状病毒肺炎(corona virus disease 2019, COVID-19)不同临床分型患者血清中新冠病毒(SARS-CoV-2)特异性IgM和IgG抗体的差异和不同时期的浓度变化,并以抗体水平变化判断核酸复阳是否为二次感染。方法选取2020年2—3月南华大学附属南华医院收治的41例COVID-19患者,共收集其患病15-65天血清标本126份;作为对照,同时选取91例发热门诊核酸检测阴性患者采集血清各1份。采用化学发光免疫分析法(chemiluminescence immunoassay, CLIA)检测血清中新冠病毒IgM和IgG抗体水平,经组间t检验和Mann-Whitney U检验对抗体浓度变化进行统计学分析。结果无症状感染者IgM和IgG抗体平均浓度高于阴性对照组,低于普通型和重型患者,差异均具有统计学意义(P0.05);普通型患者IgM和IgG抗体浓度均低于重型患者,IgM抗体差异有统计学意义(P0.05),但IgG抗体差异没有统计学意义(P=0.06);COVID-19患者急性期的IgM和IgG抗体浓度均高于康复期,差异均有统计学意义(P0.05)。复阳后,患者体内IgM和IgG抗体浓度没有增加,持续下降。结论 COVID-19患者的SARS-CoV-2 IgM和IgG抗体浓度,依无症状感染、普通型、重症型患者临床类型逐次升高,康复期逐渐降低,但大部分体内仍存在较高水平的IgG抗体。核酸复阳之后的SARS-CoV-2 IgM和IgG抗体浓度并未增高,说明未发生二次感染。     

国内首次自患者标本中同时分离的登革2型和3型病毒的鉴定

采用间接免疫荧光方法 ,检测患者血清标本中的抗登革病毒IgM和IgG抗体 ;同时将病人急性期血清接种C6 36细胞进行病毒分离。从分离的病毒悬液中提取RNA ,进行RT PCR扩增和序列测定。结果显示 ,该患者血清中存在抗登革病毒的IgM和IgG抗体。从病人血清中分离的病毒 ,经RT PCR和序列测定证实为登革 2型和 3型病毒的特异序列。表明该患者为登革 2型和 3型病毒混合感染     

用间接免疫荧光法检测流行性出血热病人尿中特异性抗体的研究

用间接免疫荧光法检测110例不同病程、病期及病型的流行性出血热病人尿中及血清中特异性抗体。尿中IgM型抗体阳性率为62.7％。尿中IgG型抗体阳性率91.8％与血清IgG型者90.9％相似,而总阳性率(IgG或IgM有一项以上阳性者的总检出率)99.1％则高于血清IgG者。20例其它疾病及10例正常人尿抗体均为阴性。结果表明尿抗体检查法是特异且可靠的,它比血清学方法简便、灵敏、为临床诊断可早期快速得出结果,不用采血有利于病人。IgM型抗体阳性率受病程、病期、病型及尿蛋白量的影响较明显。     

EB病毒DNA聚合酶基因的表达与纯化及其在鼻咽癌病人诊断中的应用

以Epstein-Barr病毒(EBV)DNA聚合酶为抗原,建立了简便、快速、敏感和特异的鼻咽癌诊断方法.构建原核表达载体pRSET-DNA聚合酶及其亚克隆pRSET-A1和pRSET-A2,在BL21(DE3)中表达的产物,经Western-blot检测其抗原性并用于检测鼻咽癌(nasopharyngeal carcinoma,NPC)病人血清中的抗体.在NPC病人血清中存在抗EB病毒DNA聚合酶的IgG抗体,并证明DNA聚合酶的抗原性主要集中于后2/3片段(A2)上.Western-bolt检测A2/IgG抗体的敏感性和特异性分别为80%和100%.对46份NPC病人血清和46份非NPC头颈癌症病人血清,用ELISA检测A2/IgA,敏感度为89%,特异度为93%.初步建立了ELISA检测NPC病人血清中A2/IgG抗体的方法,获得较高的敏感性和特异性.     

Natural and immune human antibodies reactive with antigens of virulent Neisseria gonorrhoeae: immunoglobulins G, M, And A

Natural and immune human antibodies reactive with heat-labile and heat-stable antigens of virulent Neisseria gonorrhoeae were studied by use of an indirect fluorescent-antibody (IFA) procedure. The immunoglobulin class of the reactive antibodies was identified by using fluorescein-conjugated antisera specific for human IgG, IgA, or IgM in the IFA procedure. The effects of heat and mercaptoethanol on IFA reactivities were also studied. It appeared that antibodies of the IgG, IgM, and IgA classes present in the sera of both infected persons (immune antibodies) and normal persons with no history of gonococcal infection (natural antibodies) react with heat-stable somatic antigens. Immune IgG antibodies, however, were distinguishable from natural IgG antibodies by their ability to recognize heat-labile surface antigens. The distinction between natural and immune IgM antibodies was less obvious. IgM antibodies from both infected and normal persons appeared to react with heat-labile antigens. Some, but not all, infected persons had immune IgA antibodies to heat-labile as well as to heat-stable antigens. Treatment of sera with mercaptoethanol had no effect on IgG antibodies. The IFA activity of IgM antibodies was decreased, but not abolished. The effects of mercaptoethanol on IgA antibodies were variable. Some sera showed a decrease in IgA titer, and others showed an increase in IgA activity to certain antigens. Immune IgG antibodies were more resistant to heating than were natural IgG antibodies. Natural and immune IgM antibodies appeared equally sensitive to heating. IgA activity, on the other hand, was increased by heating sera at 60 C, but was decreased at higher temperatures. Thus, it appears that natural and immune human IgG antibodies to N. gonorrhoeae may be distinguished by their interactions with heat-labile antigens and by their resistance to heating.     

Antigen binding diversity of affinity purified autoantibodies against DNA.

Naturally occurring autoantibodies against native DNA (nDNA) in SLE sera showed diverse antigen binding characteristics. The antibodies isolated by affinity chromatography using nDNA linked to Sepharose 4B exhibited specificity towards nDNA and showed strong reactivity with DNA-psoralen photoadduct by direct binding assay and competitive ELISA. The anti-DNA antibody belong to both IgG and IgM immunoglobulin classes and their ratio was 5:1. The possible significance of altered conformation of nDNA in the etiology of SLE has been discussed.     

Antibody and immune complexes induce tissue factor production by human endothelial cells

Patients with systemic lupus erythematosus (SLE) have an increased incidence of arterial and venous thromboses. The mechanism by which thromboses develop in these patients is unknown. We had previously observed that the sera of patients with SLE contain antibodies and immune complexes that can bind to endothelial cells. Because endothelial cells can synthesize tissue factor, a potent activator of coagulation, we studied the effect of IgG complexes and sera from patients with SLE on the production of tissue factor by these cells. Human umbilical venous endothelial cells incubated with heat-aggregated IgG (HA-IgG) (0.5 to 4.0 mg) elaborate procoagulant activity in a dose-dependent manner. All procoagulant activity was found in the particulate cell fraction, and none was secreted into the medium. Maximum expression of procoagulant activity required 6 to 8 hr, and its production was totally inhibited by the addition of cyclohexamide or actinomycin D. The presence of gel-filtered platelets augmented production of procoagulant activity by endothelial cells stimulated by HA-IgG. Endothelial cell procoagulant activity was not inactivated by diisofluoropropylphosphate, required the presence of Factor VII for its expression, and was neutralized by a specific anti-tissue factor antibody. Endothelial cells incubated with sera from 14 of 16 patients with SLE produced increased amounts of tissue factor compared with 21 normal sera (p less than 0.025). Fractions of two SLE sera containing monomeric IgG, IgA, or IgM, as well as fractions containing IgG complexes, each stimulated endothelial cells to produce more tissue factor than similar fractions prepared from two normal sera. These studies demonstrate that endothelial cells will produce the procoagulant tissue factor after exposure to anti-endothelial cell antibodies or IgG-containing immune complexes. The production of tissue factor by endothelial cells at sites of immune vascular injury may play a role in the development of thromboses in patients with SLE.     

Characterization of immunoglobulin classes of human antibodies to cryptococcus neoformans

Immunoglobulin G (IgG), immunoglobulin M (IgM) and immunoglobulin A (IgA) levels were determined by radial immunodiffusion techniques in sera from 11 patients with cryptococcosis. Most specimens showed increased levels of IgM. Studies with fluorescein-labeled monospecific antihuman IgG and IgM, however, indicated that IgG was the immunoglobulin reactive in the indirect fluorescent antibody (IFA) test. In addition, cross-reacting sera from mycotic infections other than cryptococcosis were also shown to contain IFA antibodies of the IgG class. Sera treated with 2-mercaptoethanol continued to react in both the IFA test and the tube agglutination test. No correlation could be established between IgG and IgM concentrations and serological reactivity in the sera evaluated in this study.     

Elevated levels of endogenous IL-6 in systemic lupus erythematosus. A putative role in pathogenesis

Elevated spontaneous IgG production is characteristic of SLE. To identify the factors that support it, IL-6, a cytokine with an important role in the differentiation of IgG-secreting cells, was studied in SLE patients. Higher than normal levels of IL-6 were found, by a B9 assay, in sera of 63 of 70 patients (p less than 0.05). IL-6 was detected in 36 of 37 active SLE sera in higher titers (p = 0.009) than those for inactive SLE (n = 33), which were higher (p less than 0.05) than healthy controls (n = 15). IL-6 mRNA was detected in freshly isolated PBMC of 11 of 11 patients but not in normal PBMC, whereas IL-1 mRNA was detected only in patients with active disease. IL-6 activity was recovered from PBMC of four SLE patients, but not from four normal donors. By immunoperoxidase, IL-6 was detected in the cytoplasm of SLE monocytes and lymphocytes. When SLE PBMC were grown in short term cultures with no deliberate stimulation, expression of the IL-6 gene declined rapidly. Accordingly, the spontaneous production of IgG by SLE PBMC could be enhanced by exogenous IL-6. Spontaneous IgG production was diminished by 20 to 65% in the presence of neutralizing antibodies to IL-6, TNF-alpha, or IL-1. In contrast, neutralization of endogenous IL-4 increased production by approximately 40%. Anti-TNF-alpha treatment decreased IL-6 content of PBMC cultures, whereas anti-IL-4 augmented it, and exogenous IL-6 reversed anti-TNF-alpha effects on IgG production. Therefore, it is possible that the neutralization of TNF-alpha and IL-4 affected IgG production by modulating the synthesis/activity of IL-6. These results support the concept that SLE B cell hyperactivity is promoted by dysregulation of endogenous cytokines and suggest that IL-6, in particular, has an important pathogenic role.     

False-Positive Anti-Toxoplasma Fluorescent-Antibody Tests in Patients with Antinuclear Antibodies

The indirect fluorescent-antibody (IFA) method for diagnosis of toxoplasmosis is widely used and is considered to be as specific as the Sabin-Feldman dye test. After observing a patient with systemic lupus erythematosus (SLE) who had a positive toxoplasma IFA test but a negative dye test, we studied sera with high titers of antinuclear antibodies from 16 SLE patients and from 2 with rheumatoid arthritis for Toxoplasma antibodies in the immunoglobulin G and M (IgG and IgM) IFA tests and the dye test. Results of these tests were compared with titers of antinuclear antibodies, precipitating antibodies to single-strand deoxyribonucleic acid (DNA), and binding antibodies by use of DNA labeled with (3)H-actinomycin D. Of 18 patients, 11 had IgG and 4 had IgM IFA Toxoplasma antibodies; only 2 had antibodies detectable in the dye test. The immunofluorescence patterns in the Toxoplasma IFA test were indistinguishable from those obtained in patients with toxoplasmosis without antinuclear antibodies. Absorption of SLE sera with DNA did not result in a decrease in Toxoplasma IFA titers. When SLE sera were absorbed with live T. gondii, a marked drop in IgG IFA titer was observed as well as a decrease in titers of antinuclear antibodies and (3)H-DNA binding. Treatment of Toxoplasma cells with deoxyribonuclease and ribonuclease did not decrease their fluorescence. These results suggest that T. gondii nuclear antigens can absorb antinuclear antibodies but do not have exposed substrates for deoxyribonuclease. Tests in which organisms containing "nuclear" antigens for IFA detection of antibodies to these organisms are used may result in "false-positives" with sera containing antinuclear antibodies.     

Specific antibodies and their role in the formation of antidiphtheria immunity

In human sera, studied with the use of the enzyme immunoassay, antidiphtheria postvaccinal antitoxic IgG and naturally acquired antibacterial IgG, IgM and IgA were detected. In the blood of children and adults aged up to 50 years antitoxic IgG were present at normal and high concentrations. In 50% of children antibacterial IgA were absent, while specific antibacterial IgM could be found at high concentrations. Changes in the content of antibacterial antibodies of different classes in sera were observed with age. More than 90% of adults had antibacterial IgA and IgG at normal and hig concentrations, while the level of IgM decreased. Under the influence of ecological, social, anthropogenic and other environmental factors the optimum levels of specific antibodies were replaced by anomalous ones, which led to an increased number of persons susceptible to diphtheria infection and in the intensity of the circulation of the infective agent. The deficiency of antidiphtheria antibacterial antibodies in the blood determined the necessity of correcting immunity by means of not only toxoid, but also bacterial antigens.     

Evaluation and Standardization of an Agglutination Test for Human Listeriosis

Human sera from patients with culturally confirmed listeriosis were tested for immunoglobulin M (IgM) and immunoglobulin G (IgG) agglutinating antibodies with trypsinized antigens of Listeria monocytogenes, Streptococcus faecalis, and Staphylococcus aureus. The response of humans to listeria infections is mainly IgM rather than IgG as found in animals. The antigens prepared from L. monocytogenes serotypes 1a, 1b, 2, 4b, and 4d were evaluated for specificity with normal sera, sera from patients with various other diseases, and sera from patients with listeriosis. The trypsinized antigens appeared to be specific for listeria antibodies with a cross-reaction rate of from 5.4 to 6%. Cross-reaction with S. aureus can be eliminated by absorption of the serum with S. aureus. This agglutination technique appears to be applicable for diagnostic testing, but, as with all serological procedures, both acute and convalescent sera should be tested.     

Characterization of mouse and human monoclonal antibodies cross-reactive with SLE serum antibodies to guanosine

Two new monoclonal antibodies, one a mouse IgM and the other a human IgM that reacted with guanosine, were compared to human serum antibodies from patients with systemic lupus erythematosus (SLE). The human monoclonal antibody was polyspecific in its binding to the nucleoside bases, whereas the mouse monoclonal antibody was relatively specific for guanosine when compared by using an enzyme-linked immunosorbent assay (ELISA). Neither antibody bound polyguanylic acid or denatured single-stranded (ss) DNA, however. Serum IgG antibodies from seven patients with SLE cross-reacted with the mouse monoclonal antibody and showed considerable specificity for guanosine. In contrast, the human serum IgG antiguanosine antibodies also bound ssDNA but not dsDNA or polyguanylic acid. Serum IgG antibodies to guanosine measured by ELISA from the seven SLE patients had a decreased response when compared to the total serum IgG response to ssDNA, and most of the antibodies that bound guanosine also bound ssDNA. These studies provide new evidence that there are specific IgG antibodies to guanosine in SLE sera that are a small fraction of the antibodies to ssDNA. Further efforts to define the role of these guanosine antibodies in SLE may provide a better understanding of the basic mechanisms responsible for the development of SLE in man.     

Serum antibodies of periodontitis patients compared to the lipopolysaccharides of Porphyromonas gingivalis and Fusobacterium nucleatum

Serum antibody titers against the lipopolysaccharides (LPSs) of Porphyromonas gingivalis and Fusobacterium nucleatum were compared between 9 periodontitis patients and 24 healthy persons. The IgG titers against the LPSs of P. gingivalis ATCC 33277(T) and W50 were clearly higher in the patients than in the healthy persons. However, IgM titers against the LPSs of P. gingivalis strains were relatively low, and no significant difference was observed between the patients and healthy persons. On the other hand, IgG and IgM titers against the LPS of Fusobacterium nucleatum JCM 8532(T) in some patients were significantly higher than those in the healthy persons, although the difference in IgG titers was not large compared to that of the LPS of P. gingivalis. These results suggest that the antibody measurement of patients' sera against the LPS of periodontal bacteria can be applied for the diagnosis of periodontitis.