Antibodies to gag gene coded polypeptides of type D retroviruses in healthy people from Guinea-Bissau.

Antibodies to proteins of Mason-Pfizer monkey virus (M-PMV) were screened in sera from 61 healthy donors living in Guinea-Bissau (4 HIV-1 and HIV-2 antibody positive HIV = human immunodeficiency virus), from 19 healthy French European blood donors, and from 9 French patients with induced immunodeficiency prior to bone marrow transplantation (all HIV-1 antibody negative). In 30 (49%) of the African sera tested, antibodies reacting against p27 and/or p14 were detected by western blot. Some of these cases were confirmed to be positive using radioimmuno precipitation assay. Only one serum from a French blood donor was detected by western blot to be slightly positive against p27 M-PMV. Thirty-two sera screened for M-PMV were also tested for squirrel monkey retrovirus by western blot. In eight (25%) sera antibodies at least against p36 were detected. Among squirrel monkey retrovirus positive sera, three were also positive with p27 M-PMV. The other five were found to be M-PMV negative.     

Diagnostic evaluation of a new combined HIV p24 antigen and anti-HIV1/2/O screening assay

To evaluate a new fourth generation assay for simultaneous detection of antibodies to the human immunodeficiency virus (HIV) 1 and 2 and HIV p24 antigen in daily routine we tested 675 sera obtained from 673 patients and compared the results to conventional antibody tests. In 546 uninfected patients the rate of unspecific reactivities was slightly higher in the new screening assay as compared to conventional antibody assays (1.1% vs. 0.4%). All 121 sera derived from patients with known HIV infection were detected correctly. In six patients from whom sera were obtained during early seroconversion the fourth generation ELISA was positive in three cases, while conventional third generation tests still were negative. In patients negative for HIV antibodies and low amounts of p24 antigen less than 100 pg/ml also the fourth generation ELISA remained negative. Thus, this new assay permits earlier detection of HIV infection and reduces the diagnostic window. It is a reliable tool for routine diagnosis of HIV, especially in blood donors and patients with high risk behavior.     

The detection of platelet alloantibodies by flow cytometry

A flow cytometric procedure was investigated for its ability to detect antibodies directed against blood group A, HLA, and PlA1 (HPA-1a) antigens. When type O sera were tested against platelets from blood group A donors, only 9 of 14 positive reactions were observed. Furthermore, the expression of blood group A varied more than 100-fold on platelets derived from individual donors. When anti-HLA-A2 and -B7 were evaluated, 11 of 11 individuals with HLA-A2 and -B7 antigens reacted. In contrast, when platelets from donors whose HLA antigens included HLA-B8 or -B12 were tested with anti-HLA-B8 or -HLA-B12, respectively, positive reactions were observed in only 3 of 7 instances, despite the fact that the lymphocytes reacted strongly. Platelets from 10 HLA-A2-positive donors, which had been stored for up to 20 months at -70 degrees C, were studied. In all cases, frozen-stored platelets reacted well with an anti-HLA-A2. Limited testing with an anti-PlA1 (anti-HPA-1a) showed equal reactivity with fresh and frozen platelets. Finally, the method was compared to a visual immunofluorescence assay using sera from patients who were refractory to platelet transfusions. The results agreed in 30 of 37 comparisons, and most discrepancies were resolved in favor of flow cytometry. It is concluded that flow cytometry is useful for detecting platelet alloantibodies and possibly for prospective platelet crossmatching, as HLA- and platelet-specific antibodies can be identified by using platelets stored frozen for several months.     

Recognition of cytomegalovirus clinical isolate antigens by sera from cytomegalovirus-negative blood donors

BACKGROUND: The most common way to prevent transmission of CMV by blood transfusion is to use blood products from seronegative donors. Screening of blood donors for CMV infection is usually based on detection of antigens obtained from the CMV laboratory strain AD 169. Recent evidence suggests that approximately up to 20 percent of CMV-negative blood donors may in fact be CMV-DNA positive by PCR analyses. STUDY DESIGN AND METHODS: In this study, sera from CMV-seronegative, CMV-seropositive, and CMV-DNA-positive/seronegative individuals, and from patients with acute and convalescent CMV infection for detection of CMV antibodies were analyzed. CMV antigens prepared from cells infected with CMV clinical isolates or the CMV laboratory strain AD 169 in ELISA and Western blot assays were used. RESULTS: All CMV-positive sera from blood donors were seropositive for the CMV antigens prepared from AD 169 (A2) or from a CMV clinical isolate (C6). Interestingly, whereas all CMV-negative blood donors were negative in tests for the CMV antigen A2, 36 percent were CMV seropositive using the CMV antigen C6 in ELISA. CONCLUSION: The data suggest that a substantial number of CMV-seronegative/CMV-DNA-positive serum samples contain antibodies that recognize CMV clinical isolate antigens.     

Normal "irregular" hemagglutinins in the sera of healthy adults found by using increased volumens of serum in agglutination and conglutination tests (author's transl)]

Using increased volumens of serum [in the Multiple-Dosage (MD) or a High Dosage (HD) test] with a sensitive manual reading technique all sera of 37 donors of blood group A2 showed irregular anti-A1(alpha1) antibodies. With the same technique, up to 1/3 of the sera of 417 healthy blood donors agglutinated red cells of a selected antigen pattern at room temperature; at 4 degrees C the ratio of positive reacting sera was much higher. The specificity of the antibodies, as indicated by the antigramme type, could be confirmed in the most cases by reacting with a series of known positive and negative reference red cells. The eluates of some of the sera yielded the same antigramme pattern as the native sera did. Some of the antibodies showed a specificity corresponding to a red cell property of the respective blood donor; but not in each case the antibodies were capable to agglutinate the donor's cells. If "autoagglutinins" were strong, frequently they revealed a character of panagglutinability, particular in the cold. With the antiglobulin test, which followed the NaCl-MD procedure, the number of positive reactions increased; on the other hand, there were some of the previously positive agglutination tests, which became negative during the course of the AHG step.     

Specific antibodies to Trypanosoma cruzi among blood donors in Los Angeles, California

BACKGROUND: Trypanosoma cruzi, the cause of Chagas' disease, is often transmitted by transfusion in Latin America. Previous studies showed that at least 1 in 1000 eligible blood donors at the Los Angeles County+University of Southern California (LAC+USC) Medical Center Blood Bank had specific antibodies to T. cruzi. In June 1993, serologic screening of prospective allogeneic donors at epidemiologic risk for T. cruzi infection was begun voluntarily. STUDY DESIGN AND METHODS: The risk of T. cruzi infection in all eligible donors was assessed by questionnaire. At-risk donors were screened serologically for antibodies to T. cruzi with an enzyme immunoassay, and confirmatory testing was done with a radioimmunoprecipitation assay. RESULTS: During the 29-month study period 1311 (39.5%) of 3320 donors were judged to be at risk for T. cruzi infection. Seven donors (1/475) were reactive by an enzyme immunoassay, and six of these seven (1/ 553) were positive in a radioimmunoprecipitation assay. All radioimmunoprecipitation assay- positive donors had been born in countries in which Chagas' disease is endemic. One person in this group had received a transfusion in his homeland. CONCLUSION: These results demonstrate that a substantive proportion of eligible blood donors at our institution have antibodies specific for T. cruzi and that a commercially available assay can be used to detect these antibodies. Our data suggest that the risk of transmission of T. cruzi by transfusion could be eliminated by serologic testing limited to persons born in or transfused in countries in which Chagas' disease is endemic.     

Identification of Babesia microti-specific immunodominant epitopes and development of a peptide EIA for detection of antibodies in serum

BACKGROUND: Babesia microti is a tick-borne agent that is increasingly implicated in transfusion-acquired infection, especially in immunocompromised and elderly recipients. To develop a test that can detect antibody responses to B. microti, peptide epitopes identified in two serocomplementary B. microti-specific antigens were used in a prototype EIA. STUDY DESIGN AND METHODS: A prototype peptide EIA was used to detect B. microti-specific antibodies in 15 sera taken before infection and 107 taken after infection from 59 individuals with known tick-borne infections previously confirmed by other methods. Three additional groups of samples were also tested: a proficiency panel of 18 sera positive for B. microti by IFA, 38 sera from blood donors confirmed positive by IFA, and 30 sera from random blood donors. RESULTS: The combination peptide detected 98 out of 107 sera taken after infection that were IgG blot positive (4 equivocal). This included all 12 samples that were PCR positive and six sera from smear-negative patients that were confirmed positive by PCR, immunoblot, or IFA. Of the IgG blot-positive specimens that were equivocal (four specimens) or did not react (nine specimens) by EIA, most had low IFA titers consistent with previous exposure. In a second evaluation, 15 out of 15 Babesia IFA-positive sera and 3 out of 3 Babesia-Ehrlichia IFA-positive sera were positive, whereas sera from 30 random donors were negative. Finally, of 38 IFA-positive blood-donor samples, 35 were positive by peptide EIA. The three EIA-negative sera were Western blot negative. CONCLUSION: Reactivity of the B. microti-specific peptide EIA shows a high correlation with IFA, PCR, and B. microti immunoblot in confirmed B. microti cases. The peptide EIA may be the most suitable B. microti infection test for adaptation to the blood bank environment if testing for B. microti is required in the future.     

Granulocyte antibody screening: evaluation of a bead‐based assay in comparison with classical methods

BACKGROUND: Granulocyte antibodies have been implicated in allo‐ and autoimmune neutropenia and in transfusion reactions. STUDY DESIGN AND METHODS: Fifty‐one sera from suspected alloimmune neutropenia or transfusion‐related acute lung injury (TRALI) and 40 sera from suspected autoimmune neutropenia were tested for granulocyte antibodies using LABScreen MULTI (One Lambda, Inc.), compared with classical tests (flow cytometry [FC] and granulocyte agglutination [GAT] followed by monoclonal antibody–specific immobilization of granulocyte antigens [MAIGA]). RESULTS: In alloimmune situations, 48 sera were concordant (94%), two sera positive for HNA with LABScreen MULTI were negative by FC/GAT and/or MAIGA, and one serum sample negative for HNA with LABScreen MULTI was positive by classical tests. In autoimmune neutropenia, 30 sera were concordant (75%), four sera positive for HNA with LABScreen MULTI were negative by FC/GAT and/or MAIGA, and six sera negative for HNA with LABScreen MULTI were positive by FC/GAT and/or MAIGA. For detection of autoantibodies, the LABScreen MULTI was less concordant. However, with the exception of one case, the discrepancies were observed in sera that did not show a clear specificity. CONCLUSIONS: LABScreen MULTI correlated well with our classical methods for HNA‐1 and HNA‐2a antibody screening. It can be used for screening blood donors or patients suspected of TRALI, but GAT is still needed for HNA‐3a antibody screening.     

血清ACCP在HCV感染并发冷球蛋白血症的诊断价值

目的探讨血清抗环瓜氨酸肽抗体(ACCP)在丙型肝炎病毒(HCV)感染并发冷球蛋白血症中的诊断价值。方法收集HCV感染患者20例、HCV感染伴冷球蛋白血症患者5例、混合型冷球蛋白血症(MC)患者5例和健康献血者20例,分别用酶联免疫吸附试验(ELISA)和比浊法测定其血清ACCP和类风湿因子(RF)水平。结果20例HCV感染患者,血清ACCP试验均为阴性,最大值为10U。其中9例(45%)RF>15U/ml,3例(15%)RF>50 U/ml,最高者RF为526 U/ml。HCV感染伴冷球蛋白血症患者5例中,3例(60%)血清ACCP试验为阳性,均值为47U;混合型冷球蛋白血症患者5例中,4例(80%)RF试验阳性,其中3例(60%)RF>50 U/ml,最大值为540 U/ml;1例(20%)冷球蛋白血症患者ACCP试验呈临界值阳性结果(25U)。20例健康献血者血清ACCP和RF试验均为阴性。结论ACCP检测有助于慢性HCV感染并发冷球蛋白血症患者的早期诊断。     

Anti-GOR in hepatitis D: specific association with hepatitis C virus superinfection

Summary A group of 113 patients with chronic hepatitis D was investigated for the presence of anti-GOR and liver kidney microsomal antibodies. Eight patients were anti-GOR positive and also positive for hepatitis C virus-infection. In sera from 16 patients liver-kidney microsomal antibodies were detectable by immunofluorescence. They were classified as LKM-3 due to their fluorescence pattern. Two of the LKM-3-positive sera were also anti-hepatitis C virus and anti-human immunodeficiency virus positive. None of these patients were positive for anti-GOR. Fourteen sera from LKM-3-positive patients reacted in Western blot with a microsomal protein at 55 kDa that differs from the 50-kDa LKM-1 (cytochrome P450IID6) antigen. Our studies demonstrate that hepatitis D virus itself does not induce an autoimmune reaction against the GOR antigen and that autoimmunity to the LKM-3 antigen induced by hepatitis D virus infection does not correlated with anti-GOR. These studies support the specificity of the anti-GOR response for hepatitis C virus infection.     

Frequency of human immunodeficiency virus (HIV) infection among contemporary anti-HIV-1 and anti-HIV-1/2 supplemental test- indeterminate blood donors. The Retrovirus Epidemiology Donor Study

Background: Follow-up studies from the mid-1980s showed that 1 to 5 percent of blood donors testing reactive in anti-human immunodeficiency virus type 1 (HIV-1) enzyme immunoassay (EIA) and testing indeterminate in Western blot were infected with HIV-1 and were in the process of seroconverting. The present study was conducted to establish the rate of HIV infection among contemporary anti-HIV-1/HIV type 2 (HIV-2) EIA- reactive, Western blot-indeterminate donors. Study Design and Methods: Donations (n = 607) with indeterminate HIV supplemental test results were identified by screening 3,021,342 donations given from November 1990 through August 1993 at five participating blood centers. Consenting donors were enrolled and samples taken 4 to 8 weeks after donation. Follow-up sera were tested by EIA and Western blot for anti- HIV-1 seroconversion and by type-specific peptide assays for antibodies to HIV-2 and HIV-1 subtype O. Peripheral blood mononuclear cells and/or plasma from the follow-up samples were tested for HIV-1 DNA and/or RNA by polymerase chain reaction. The rate of HIV-1 infection among Western blot-indeterminate donors was also estimated by multiplying the incidence rate of HIV-1 seroconversion in this donor population by the estimated duration of the EIA-reactive and Western blot-indeterminate window during seroconversion (8.5 days). Results: Supplemental test- indeterminate donors (n = 355) enrolled a median of 38 days after donation; 265 (75%) of these donors were identified as indeterminate after an anti-HIV-1/2 EIA-reactive donation. Enrolled and non-enrolled donors had similar distributions of demographic characteristics and band patterns. Follow-up samples from all 355 donors tested negative for HIV-1 in polymerase chain reaction. Follow-up sera tested Western blot-negative in 54 cases (15%) and Western blot-indeterminate in 299 (84%). Two follow-up sera (0.6%) were interpreted, according to manufacturer's package insert criteria, as Western blot positive with p24 and gp41 bands and/or gp120/160 bands; however, paired testing of index and follow-up sera from these two cases showed identical Western blot and EIA reactivity, and polymerase chain reaction was negative for HIV RNA and DNA, which ruled out HIV infection. The absence of HIV infection in 355 Western blot-indeterminate donors was consistent with our incidence-based model analysis, which yielded an estimate of one HIV-1 infection for every 215 Western blot-indeterminate donations (95% CI, 1/39-1/8333). Conclusion: Contemporary blood donors classified as indeterminate in supplemental HIV testing are infrequently infected with HIV. Donors whose follow-up samples test negative in anti-HIV-1/2 EIAs and negative or persistently indeterminate in Western blots should be considered eligible for reinstatement.     

基于肽抗原的间接酶联免疫吸附法检测抗水通道蛋白4抗体在神经精神狼疮中的临床意义

目的：建立抗水通道蛋白4（AQ-4）抗体的检测方法,评估抗AQ-4抗体在神经精神狼疮（NPSLE）中的临床意义。方法：用3段AQ-4细胞外肽段包板,建立基于肽抗原的间接酶联免疫吸附（ELISA）检测方法,检测49例健康人、54例其他风湿病患者（32例多肌炎/皮肌炎,10例干燥综合征和12例类风湿关节炎患者）、105例系统性红斑狼疮（SLE）患者和103例NPSLE患者的血清中的抗AQ-4抗体;检测22例非风湿病患者、31例SLE患者、96例NPSLE、27例合并结核感染的SLE患者和8例隐球菌脑膜炎患者的脑脊液标本中抗AQ-4抗体。结果：以健康人（对照组）的平均光密度（OD）＋3标准差（SD）为临界值,血清标本阳性率在其他风湿病组为1.8%（1/54）;SLE组为14.3%（15/105）;NPSLE组为22.3%（23/103）。脑脊液标本阳性率在对照组为0%;SLE组为12.9%（4/31）;NPSLE组为29.2%（28/96）;SLE合并结核性脑膜炎者为37%（10/27）;SLE合并隐球菌脑膜炎者为0%（0/8）。SLE组合并NPSLE组患者的血清和脑脊液中的抗AQ-4抗体显著增加（P〈0.01）,SLE组血清和脑脊液中的抗AQ-4抗体水平相似（P〉0.05）。NPSLE组脑脊液中的抗体检出率（29.2%）较血清中抗体检出率（22.3%）增高（P〈0.01）。在SLE合并TB组的脑脊液中,抗AQ-4抗体的检出显著增高（P〈0.01）。结论：抗AQ-4抗体在SLE和NPSLE患者的血清和脑脊液中显著升高,尤其是脑脊液中。SLE合并结核性脑膜炎患者的抗AQ-4抗体显著升高,提示抗AQ-4抗体是狼疮合并结核性脑病的易患因素。     

Evaluation of RNA and E2 antibodies in prospectively followed recipients of hepatitis G virus-infected blood

BACKGROUND: Hepatitis G virus (HGV) has recently been cloned and tests for HGV RNA and envelope antibodies (anti-E2) have been developed. HGV infection is widespread among blood donors worldwide, but the clinical and serologic outcome of transfusion-associated HGV infection has not been fully characterized. STUDY DESIGN AND METHODS: Consecutive blood donors (n = 2210) were investigated for HGV markers (RNA and anti-E2). The recipients of HGV RNA-positive blood were followed for 1 year after transfusion. RESULTS: Forty-two blood donors (1.9%) were positive for HGV RNA. Eight recipients of HGV RNA-positive blood were retrospectively identified within 2 weeks of transfusion and prospectively followed. In four patients, the presence of anti-E2 before transfusion or an early antibody response protected them from reinfection or prevented HGV persistence, while, in the remaining four patients, transient or persistent viremia was detected shortly after exposure. None of the infected recipients had any evidence of liver disease. CONCLUSION: These results do not support the screening of donors to prevent transfusion-associated HGV infection.     

The importance of antibodies against low-incidence RBC antigens in complete and abbreviated cross-matching

BACKGROUND: It is common practice to perform an antiglobulin cross-match only when unexpected RBC alloantibodies are present, to detect antibodies against additional RBC antigens. In this study, the incidence of unexpected antibodies to low-incidence antigens (Ab-LIA) over a period of 23 years was investigated. STUDY DESIGN AND METHODS: Records of RBC antibodies and the accompanying transfusion history from 1978 through 2000 was retrospectively examined. Complete cross-matches were performed for all RBC transfusions before 1991. As of 1991, the type-and-screen policy was applied. To study the incidence of anti-Wra, a prospective study was conducted on sera from 462 patients sent to the transfusion laboratory and 486 blood donors. RESULTS: The records of 1795 patients containing 2257 RBC antibodies were examined. In 89 patients, a total of 94 Ab-LIAs was found. Anti-Wra was the most frequently encountered Ab-LIA. Thirty-nine patients had Ab-LIA in combination with other antibodies, 20 of which were autoantibodies. Eighty percent of these Ab-LIA were found at the first positive antibody screening test. Fifty-one solitary Ab-LIA were found in 50 patients, 37 during antibody screening tests, and 14 after positive complete cross-matches conducted before 1991. After an RBC antibody was detected, 664 patients received a total of 7792 RBC transfusions. Since the introduction of the type-and-screen policy, only one anti-Wra has been discovered during complete cross-matching. No transfusion reactions due to Ab-LIA were reported during the study period. In the prospective study, 12.3 percent of patients and 4.3 percent of blood donors had anti-Wra. CONCLUSIONS: Although Ab-LIAs are found coincidentally in the sera of only 2 to 3 percent of patients with other RBC antibodies, they are formed often. Because we found no difference in serologic incompatibility, due to Ab-LIAs, between patients with and without other blood group antibodies, we conclude that blood can be transfused safely to patients without performing a complete cross-match.     

佛山市无偿献血者人类T淋巴细胞白血病病毒感染情况调查

目的 探讨广东省佛山市无偿献血人群中,人类T淋巴细胞白血病病毒(HTLV)感染状况,评估经血液传播HTLV的风险,保障临床输血安全.方法 选择2016年2月至12月,于佛山市参加无偿献血的69 275例献血者作为研究对象.采用酶联免疫吸附试验(ELISA)法对献血者血浆中HTLV-Ⅰ/-Ⅱ抗体进行初步筛查.对初检结果呈反应性的标本再进行双孔复检.对复检结果呈反应性的标本,则判定为HTLV-Ⅰ/-Ⅱ抗体初筛结果呈阳性.对初筛结果呈阳性的标本采用Western印迹法进行确证.统计不同性别、年龄、学历、户籍及献血次数献血人群的HTLV-Ⅰ/-Ⅱ抗体的初筛阳性率,并且采用统计学方法,分别对不同献血人群的HTLV-Ⅰ/-Ⅱ抗体初筛阳性率进行比较.结果 ①本研究69 275例无偿献血者中,HTLV-Ⅰ/-Ⅱ抗体呈阳性者为17例,HTLV-Ⅰ/-Ⅱ抗体初筛阳性率为0.025％.其中,仅2例献血者的HTLV-Ⅰ/-Ⅱ抗体的Western印迹法确证试验结果呈阳性,确证阳性率为0.003％.②本研究69 275例无偿献血者中,女性献血者的HTLV-Ⅰ/-Ⅱ抗体初筛阳性率为0.042％(11/26 291),高于男性的0.014％(6/42 984),并且差异有统计学意义(x2=5.17,P=0.023).不同年龄段献血者中,46～55岁年龄段献血者的HTLV-Ⅰ/-Ⅱ抗体初筛阳性率最高(0.084％,4/4 768);并且不同年龄段献血者HTLV-Ⅰ/-Ⅱ抗体初筛阳性率总体比较,差异有统计学意义(x2=8.09,P=0.044).不同学历献血者中,初中及以下学历献血者HTLV-Ⅰ/-Ⅱ抗体初筛初筛阳性率最高(0.063％,7/11 113);并且不同学历献血人群HTLV-Ⅰ/-Ⅱ抗体初筛阳性率总体比较,差异有统计学意义(x2 =7.97,P=0.047).外地户籍献血者HTLV-Ⅰ/-Ⅱ抗体初筛阳性率(0.033％,15/45 274)高于本地户籍献血者(0.008％,2/24 001),并且差异有统计学意义(x2=3.93,P=0.047).2次及以上献血者HTLV-Ⅰ/-Ⅱ抗体初筛阳性率(0.034％,16/46 414)高于首次献血者(0.004％,1/22 861),并且差异有统计学意义(x2=5.65,P=0.017).结论 佛山市属于无偿献血人群感染HTLV的低发生率区或者非流行区.女性、老年、学历低、外地户籍及多次献血的无偿献血人群感染HTLV的风险较大.鉴于输血安全,建议献血前常规检测所有无偿献血者的HTLV-Ⅰ/-Ⅱ抗体,同时对血液进行去除白细胞过滤处理.     

Laboratory diagnosis of heparin-associated thrombocytopenia and comparison of platelet aggregation test, heparin-induced platelet activation test, and platelet factor 4/heparin enzyme-linked immunosorbent assay

BACKGROUND : As clinical diagnosis of heparin-associated thrombocytopenia (HAT) is often difficult, confirmation by sensitive laboratory assays is desirable. STUDY DESIGN AND METHODS : The sensitivity of the heparin-induced platelet activation (HIPA) test and the platelet aggregation test (PAT) was prospectively compared by using the sera of 209 patients with the putative diagnosis of HAT. Both assays were performed concomitantly with platelets of the same four donors using a different combination of donors from day to day. Further, all sera were assessed with a platelet factor 4 (PF4)/heparin enzyme-linked immunosorbent assay (ELISA). RESULTS : Positive results were obtained with 33 percent of sera in the PF4/heparin ELISA, with 33.5 percent of sera in the HIPA test, and with 11.5 percent of sera in the PAT. The PF4/heparin ELISA and the HIPA test showed no difference in sensitivity (p = 0.27 by McNemar's test) and were more sensitive than PAT (p < 10(-8) by McNemar's test). However, they recognized different patient cohorts. Nine HIPA-indeterminate and 12 HIPA-negative sera were positive in the PF4/heparin ELISA. Eight of the nine indeterminate sera caused platelet activation with high heparin concentrations in the HIPA test. Eleven of the 12 negative sera contained no IgG, but 9 contained IgM and 2 contained IgA HAT antibodies. Four sera that were indeterminate in the PF4/heparin ELISA and 18 sera that were negative were positive in the HIPA test. None of the sera that were positive in the PAT was missed in the HIPA test, but two of those were negative in the PF4/heparin ELISA. All sera were assessed with four low-molecular-weight heparins and a low-molecular- weight heparinoid in the HIPA test with platelets from the same four donors. Low-molecular-weight heparin caused platelet activation with positive sera in 98 percent of tests, and the heparinoid did so in 10 percent; in a further 12.8 percent, crossreactivity to the low- molecular-weight heparinoid could not be excluded. CONCLUSION : The majority of HAT antibodies react with a PF4/heparin complex, but there is strong evidence that other antigens are involved in some patients. The HIPA test and the PF4/heparin ELISA are sensitive for diagnosing HAT, and they complement one another.     

Clinical utility of a competitive ELISA to detect antibodies against Treponema pallidum

Screening for Treponema pallidum infection is carried out on a large human population. To reduce costs, fewer tests which still offer adequate sensitivity and specificity could be performed. We studied the reliability of a novel indirect ELISA method to test for this infection. Several panels of sera were used that corresponded to 40 primary infections (group 1), 13 recurrences (group 2), 348 latent infections (group 3), 5 samples with anticardiolipin antibodies (group 4), 15 samples from patients with Lyme borreliosis (group 5), and 400 samples from blood donors and healthy pregnant women (group 6). The ELISA showed a global sensitivity and specificity of 100 and 99.5%, respectively. Our evaluation shows that Enzygnost Syphilis is a sensitive, specific, and simple test to screen for this infection.     

An ELISA method in the diagnosis of typhoid fever

Anti-S. typhi IgG and IgM antibodies were detected by an ELISA test using whole S. typhi as antigen. Among sera of patients suffering from typhus, 100% were positive for IgG and 78.9% for IgM. In the control group (blood donors and patients with various diseases) positivities were 1.01% for IgG and 1.01% for IgM.     

Antigen/antibody content of circulating immune complexes in HIV-infected patients

Dual infection with HIV and hepatitis B virus (HBV) is not an uncommon feature. Immunity impairment due to HIV infection can be the cause of a higher rate of HBV replication with less intensive liver damage and less effective immune response to HBV. Many HIV-infected patients have an elevated level of circulating immune complexes (CIC) in serum, throughout all stages of illness evolution. The aim of our study was to estimate p24 and HBsAg content of CIC in dually infected patients, and the prevalence of major classes of complexed antibodies (IgM and IgG). We examined 146 samples of sera from 105 HIV positive patients of the Institute for Infectious and Tropical Diseases during 1992 and 1993. On those sera we performed p24Ag and HbsAg detection, with and without prior dissociation of CIC, we determined serum level of CIC and immunoglobulin classes IgM and IgG level in sera and in polyethilenglycol (PEG) precipitates of sera. Acid dissociation of immune complexes revealed a high proportion of HIV antigen positive sera in all stages of HIV disease progression. HbsAg in serum of HIV positive patients was also found coupled in immune complexes much more frequently than in the HIV negative control group. In many instances both antigens were simultaneously found coupled in CIC. Immune complexes detected have been shown to contain both IgM and IgG immunoglobulins, while IgM antibodies were associated to immune complexes in higher proportion than IgG, compared to total serum immunoglobulins.