RESUMO
BACKGROUND: Our laboratory system tests sera for herpes simplex virus type 2 (HSV-2) IgG using the DiaSorin Liaison chemiluminescent immunoassay (CIA), with the option to confirm positive samples by a laboratory-developed HerpeSelect inhibition assay. As part of the confirmation process, the HerpeSelect HSV-2 IgG enzyme immunoassay (EIA) is performed. This study investigated the relationship between DiaSorin HSV-2 IgG CIA-positive indices and HerpeSelect HSV-2 IgG EIA results. METHODS: HerpeSelect HSV-2 IgG EIA results were compiled for a cohort of consecutive DiaSorin HSV-2 IgG CIA-positive (index ≥1.10) samples. To further characterize DiaSorin CIA-positive samples that were positive (concordant) or negative (discordant) by the HerpeSelect EIA, a separate composite reference study panel was constructed and also tested using the Biokit HSV-2 IgG assay and an HSV-2 IgG inhibition assay developed for the DiaSorin instrument. Samples were classified as DiaSorin HSV-2 IgG true positive or false positive based on a composite reference using HerpeSelect EIA, Biokit, and DiaSorin inhibition results. RESULTS: Of 2305 consecutive DiaSorin HSV-2 IgG CIA-positive samples, 411 (17.8%) were HerpeSelect HSV-2 IgG EIA negative; 343 of 411 (83%) had DiaSorin indices of 1.10 to 3.00. For the composite reference study panel (N = 120), 59 of 60 discordant samples were classified as DiaSorin HSV-2 IgG false positive based on the composite reference, whereas 58 of 60 concordant samples were classified as true positive. CONCLUSIONS: Nearly all DiaSorin HSV-2 IgG CIA-positive but HerpeSelect HSV-2 IgG EIA-negative sera are falsely positive in the DiaSorin CIA. Furthermore, most DiaSorin false-positive samples exhibit low-positive indices, suggesting that guidelines for confirmatory testing should include low-positive samples by CIA and EIA.
Assuntos
Herpes Genital , Herpes Simples , Anticorpos Antivirais , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Herpes Genital/diagnóstico , Herpes Simples/diagnóstico , Herpesvirus Humano 2 , Humanos , Imunoglobulina G , Masculino , Sensibilidade e EspecificidadeRESUMO
A total of 1,200 serum samples that were tested for SARS-CoV-2 IgG antibody using the Abbott Architect immunoassay targeting the nucleocapsid protein were run in 3 SARS-CoV-2 IgG immunoassays targeting spike proteins (DiaSorin Liaison, Ortho Vitros, and Euroimmun). Consensus-positive and consensus-negative interpretations were defined as qualitative agreement in at least 3 of the 4 assays. Agreement of the 4 individual assays with a consensus-negative interpretation (n = 610) ranged from 96.7% to 100%, and agreement with a consensus-positive interpretation (n = 584) ranged from 94.3% to 100%. Laboratory-developed inhibition assays were utilized to evaluate 49 consensus-negative samples that were positive in only one assay; true-positive reactivity was confirmed in only 2 of these 49 (4%) samples. These findings demonstrate very high levels of agreement among 4 SARS-CoV-2 IgG assays authorized for emergency use, regardless of antigen target or assay format. Although false-positive reactivity was identified, its occurrence was rare (no more than 1.7% of samples for a given assay).
Assuntos
Infecções por Coronavirus , Nucleocapsídeo , Pandemias , Pneumonia Viral , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave , Anticorpos Antivirais , Betacoronavirus , COVID-19 , Teste para COVID-19 , Técnicas de Laboratório Clínico , Infecções por Coronavirus/diagnóstico , Humanos , Imunoensaio , Imunoglobulina G , SARS-CoV-2 , Sensibilidade e Especificidade , Glicoproteína da Espícula de CoronavírusRESUMO
BACKGROUND: Dengue viruses (DENV-1-4) pose a transfusion-transmission risk. This study estimated the dengue RNA detection period in asymptomatic blood donors and relationships between donor viremia and dengue incidence during a large epidemic. METHODS: Donor samples from the 2012 dengue transmission season in Rio de Janeiro, Brazil, were tested for DENV RNA by a transcription-mediated amplification (TMA) assay, with DENV types and viral loads determined by polymerase chain reaction. Samples collected during the first and last weeks of enrollment were tested for DENV immunoglobulin (Ig) G and IgM to estimate incidence during the study period, which was analyzed relative to nucleic acid amplification technology (NAT) yield to estimate the duration of NAT-detectable viremia and compared with reported clinical dengue cases in Rio. RESULTS: Samples from 16 241 donations were tested; 87 (0.54%) were confirmed as DENV-4 RNA positive. Dengue IgM-positive/IgG-positive reactivity increased from 2.8% to 8.8%, indicating a 6.2% incidence (95% confidence interval [CI], 3.2%-9.1%) during the study period. Based on these data, we estimated a 9.1-day period (95% CI, 4.4-13.9 days) of RNA detectable with TMA. With 100 475 reported cases of clinical dengue, 1 RNA-positive donation was identified per 800 DENV cases. CONCLUSIONS: These parameters allow projections of dengue incidence from donor NAT yield data and vice versa, and suggest that viremic donations will be rare relative to clinical disease cases.
Assuntos
Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Transfusão de Sangue , Vírus da Dengue/imunologia , Dengue/sangue , Dengue/transmissão , Viremia/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Doadores de Sangue/estatística & dados numéricos , Brasil/epidemiologia , Culicidae/virologia , Dengue/epidemiologia , Surtos de Doenças/estatística & dados numéricos , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Testes Sorológicos , Viremia/epidemiologia , Viremia/transmissãoRESUMO
West Nile virus (WNV) is now endemic in the United States. Protection against infection is thought to be conferred in part by humoral immunity. An understanding of the durability and specificity of the humoral response is not well established. We studied the magnitude and specificity of antibody responses in 370 WNV-seropositive blood donors. We also recalled 18 donors who were infected in 2005 to compare their antibody responses at 6 months following infection versus at 5 years postinfection. There were no significant differences in IgG antibody levels based on age, sex, or recent infection (as evidenced by IgM positivity). Specific antibody responses by viral plaque reduction neutralization testing (PRNT) were seen in 51/54 subjects evaluated. All donors who were seropositive in 2005 remained seropositive at 5 years and maintained neutralizing antibodies. IgG levels at 5 years postinfection showed fairly minimal decreases compared with the paired levels at 6 months postinfection (mean of paired differences,-0.54 signal-to-cutoff ratio (S/CO) units [95% confidence interval {CI}, -0.86 to -0.21 S/CO units]) and only minimal decreases in PRNT titers. WNV induces a significant antibody response that remains present even 5 years after infection.
Assuntos
Anticorpos Antivirais/sangue , Febre do Nilo Ocidental/imunologia , Vírus do Nilo Ocidental/imunologia , Anticorpos Neutralizantes/sangue , Doadores de Sangue , Humanos , Imunoglobulina G/sangue , Estudos Longitudinais , Fatores de Tempo , Estados UnidosRESUMO
BACKGROUND: Approximately 6% of sera positive in a dengue virus IgM-capture enzyme immunoassay (EIA) represent false-positives due to interaction between IgM and horseradish peroxidase (HRP)-labeled monoclonal antibody (MAb) 6B6C1 (IgG2a). To better understand this interaction, we assessed the reactivity of captured IgM from these sera with other HRP-labeled MAbs. METHODS: Fifty dengue IgM false-positive sera (recognizing 6B6C1) were evaluated for IgM reactivity with the HRP-labeled MAbs H3A4 (IgG2a), 53.8 (IgG2b), and IL-A2 (IgG1). The sera were also tested in an EIA for human anti-mouse antibody (HAMA). RESULTS: Forty-three sera (86%) reacted with IgG2a MAb (H3A4). Most (31/43 = 72%) of these sera recognizing 6B6C1 and H3A4 also recognized the IgG2 MAb and/or the IgG1 MAb. In contrast, HAMA was increased in only 9 of 50 (18%) sera reacting with 6B6C1. CONCLUSIONS: IgM from most sera-binding IgG2a MAb 6B6C1 also binds another IgG2a MAb, suggesting that IgM-6B6C1 reactivity is not idiotype specific. In many cases, IgM recognizing 6B6C1 also binds MAbs of other IgG subclasses, but is negative in a HAMA assay. These findings indicate that samples positive in IgM-capture EIAs utilizing conjugated MAbs should always be retested in the absence of antigen to identify false-positive reactivity caused by direct IgM-MAb interaction.
Assuntos
Anticorpos Monoclonais/química , Técnicas Imunoenzimáticas/métodos , Imunoglobulina G/química , Imunoglobulina M/química , Animais , Anticorpos Monoclonais/metabolismo , Especificidade de Anticorpos , Dengue/sangue , Dengue/diagnóstico , Dengue/imunologia , Reações Falso-Positivas , Humanos , Técnicas Imunoenzimáticas/normas , Imunoglobulina G/metabolismo , Imunoglobulina M/sangue , Imunoglobulina M/metabolismo , Camundongos , Ligação ProteicaRESUMO
To determine risk for West Nile virus (WNV) neuroinvasive disease in North Dakota, we tested plasma samples from blood donors for WNV IgG and compared infection rates with reported WNV neuroinvasive disease incidence. We estimate that 1 in 244 WNV infections leads to neuroinvasive disease; risk is substantially increased among men and older persons.
Assuntos
Meningite Viral/epidemiologia , Febre do Nilo Ocidental/epidemiologia , Vírus do Nilo Ocidental/imunologia , Adolescente , Adulto , Idoso , Anticorpos Antivirais/sangue , Feminino , Humanos , Incidência , Masculino , Meningite Viral/imunologia , Meningite Viral/virologia , Pessoa de Meia-Idade , North Dakota/epidemiologia , Fatores de Risco , Estudos Soroepidemiológicos , Febre do Nilo Ocidental/imunologia , Febre do Nilo Ocidental/virologia , Adulto JovemRESUMO
Some sera tested for 1-3-beta-D-glucan to identify invasive fungal infections exhibit interference. To assess interference transience, we evaluated results for 426 patients with an interference sample followed by a later sample. Interference was transient for 73% of patients (later sample negative or positive); median time between samples was 8 days.
Assuntos
Infecções Fúngicas Invasivas , beta-Glucanas , Glucanos , Humanos , Imunoensaio , ProteoglicanasRESUMO
West Nile virus (WNV) IgM antibodies typically indicate a recent infection. However, WNV IgM antibodies can remain detectable for months to years following illness onset. We found that 23% (11/47) of samples tested with a WNV ELISA and 43% (20/47) of samples tested with WNV microsphere immunoassay (MIA) at 16-19 months following WNV illness onset were positive for IgM antibodies. The proportion of samples testing positive for WNV IgM by ELISA decreased over time, but 5% (2/44) of individuals remained positive at 60-63 months after their acute illness and 4% (2/50) were WNV IgM equivocal at 72-81 months. Testing by MIA showed the same general trend of decreased proportion positive over time though the rates of positivity were higher at most time points compared with the ELISA, including 6% (3/50) of participant's samples identified as IgM positive by MIA at 72-81 months post their acute illness. With the MIA, there also was a high proportion of samples with nonspecific results at each time point; average of 23% across all time points. Clinicians and public health officials should consider these findings along with clinical and epidemiologic data when interpreting WNV IgM antibody test results.
RESUMO
BACKGROUND: Chikungunya virus (CHIKV) represents a threat to the United States, because humans amplify CHIKV and vectors that transmit CHIKV are present. METHODS: We described the epidemiology of laboratory-confirmed chikungunya fever (CHIK) cases in the United States in 1995-2009 and compared states with CHIKV vectors with states with returning viremic CHIK cases. For 2006-2009, we evaluated reporting of CHIK cases to ArboNET, the arboviral surveillance system. RESULTS: In 1995-2009, 109 CHIK cases were identified in the United States; all adult travelers. Sixty-two subjects (57%) had recently visited India, and 13 (12%) had CHIKV viremia. Of the 26 jurisdictions with CHIK cases, 22 (85%) reported the presence of CHIKV vectors. Twelve viremic travelers returned to 6 states with CHIKV vectors. Of the 106 cases identified in 2006-2009, only 27 (25%) were reported to ArboNET, with a median of 122 days (range, 44-273 days) between illness onset and reporting. CONCLUSIONS: No locally acquired CHIK cases were identified. However, several viremic travelers returned to states with CHIKV vectors and presented a risk for local transmission. Incomplete and delayed reporting made ArboNET less useful. To minimize the risk of CHIKV spread in the United States, healthcare providers and public health officials should be educated about recognition, diagnosis, and reporting of CHIK cases.
Assuntos
Vírus Chikungunya/isolamento & purificação , Adulto , Idoso , Infecções por Alphavirus/epidemiologia , Febre de Chikungunya , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Viagem , Estados Unidos/epidemiologiaRESUMO
Published studies show that >99% of sera reactive in the reverse syphilis testing algorithm (RSTA) screening assay with an index above an assay-specific threshold confirm as reactive, with either a rapid plasma reagin-reactive (RPRR) or RPR-nonreactive/Treponema pallidum particle agglutination-reactive (TPPAR) result. However, the relationship between screen indices and confirmatory patterns has not been characterized. We thus assessed confirmatory testing results for 577 sera submitted for RSTA testing and a screen-reactive result in the DiaSorin Liaison assay. The median screen index was significantly higher for RPRR samples than TPPAR samples (55.6 versus 10.4), and the proportion with indices >28.3 (median for all 577 samples) was significantly higher for RPRR versus TPPAR samples (82% versus 26%). However, RPRR titers did not significantly correlate with screen indices (R2â¯=â¯0.02). These findings demonstrate a significant relationship between RSTA screen indices and confirmatory assay results. The clinical utility of this relationship requires further study.
Assuntos
Algoritmos , Sorodiagnóstico da Sífilis , Sífilis/diagnóstico , Treponema pallidum/imunologia , Adulto , Anticorpos Antibacterianos/sangue , Feminino , Humanos , Imunoensaio , Modelos Lineares , Masculino , Sífilis/imunologia , Sífilis/microbiologia , Sorodiagnóstico da Sífilis/métodos , Sorodiagnóstico da Sífilis/normasRESUMO
Centers for Disease Control guidelines recommend hepatitis C virus (HCV) RNA testing of all HCV IgG-reactive samples, although earlier studies found that IgG-reactive samples with low indices were negative in qualitative RNA assays. To determine if previous study results could be confirmed using current real-time RT-PCR technology, we investigated the relationship between HCV IgG index (Ortho VITROS) and quantitative HCV RNA results (cobas HCV) for 2368 consecutive IgG-reactive sera. Results were segregated into Low (1.00-16.0), Medium (16.1-30.0), and High (>30.0) IgG index groups. Although median viral load (VL) of RNA-positive samples was similar in all 3 groups, the percentage with low VL (1.18-4.16 log IU/mL) was increased for the Low group. Further analysis of the Low group revealed that 23 of 370 (6%) samples with IgG indices ≤8.00 were RNA-positive, and 13/23 (57%) had low VL. Our analysis supports the Centers for Disease Control recommendation to test all HCV IgG-reactive sera for HCV RNA.
Assuntos
Hepacivirus , Hepatite C , RNA Viral , Reação em Cadeia da Polimerase em Tempo Real/métodos , Carga Viral/métodos , Feminino , Hepacivirus/genética , Hepacivirus/imunologia , Hepatite C/diagnóstico , Hepatite C/imunologia , Hepatite C/virologia , Anticorpos Anti-Hepatite C/sangue , Humanos , Imunoglobulina G/sangue , Masculino , Pessoa de Meia-Idade , RNA Viral/sangue , RNA Viral/genéticaRESUMO
CDC guidelines recommend confirmatory testing of sera with low-positive indices (1.10-3.50) in the HerpeSelect® (HSLT) HSV-2 IgG screening assay. To determine if this recommendation is adequate for our patient population, we reviewed HSLT HSV-2 IgG screening indices for 262 screen-positive sera (index >1.10) tested in our confirmatory assay, which assesses inhibition of binding to recombinant gG2 by HSV-1- and HSV-2-infected cell lysates. To determine how the recommendation affects other screening assays, we tested these samples in the Liaison® HSV-2 IgG assay. Of 124 false-positive sera, 20% and 39% had an index >3.50 in the HSLT and Liaison screening assays, respectively. In both assays, 51% of 63 indeterminate sera (inhibition by HSV-1 lysate) had indices >3.50. Similarly, ≥75% of 75 true-positive samples exhibited indices >3.50 in both assays. Thus, confirmatory testing only of sera with low-positive HSV-2 IgG indices misses some false-positive and indeterminate samples, leading to misdiagnosis of HSV-2 infection.
Assuntos
Herpes Genital/diagnóstico , Herpesvirus Humano 2/isolamento & purificação , Imunoensaio/normas , Testes Sorológicos/normas , Anticorpos Antivirais/sangue , Reações Falso-Positivas , Herpesvirus Humano 1/imunologia , Herpesvirus Humano 2/imunologia , Humanos , Imunoglobulina G/sangue , Proteínas do Envelope Viral/imunologiaRESUMO
Surveillance studies are required to estimate the impact of pneumococcal vaccination in both children and the elderly across Europe. The World Health Organization (WHO) recommends use of enzyme immunoassays (EIAs) as standard methods for immune surveillance of pneumococcal antibodies. However, as levels of antibodies to multiple serotypes are monitored in thousands of samples, a need for a less laborious and more flexible method has evolved. Fluorescent-bead-based multiplex immunoassays (MIAs) are suitable for this purpose. An increasing number of public health and diagnostic laboratories use MIAs, although the method is not standardized and no international quality assessment scheme exists. The EU Pneumo Multiplex Assay Consortium was initiated in 2013 to advance harmonization of MIAs and to create an international quality assessment scheme. In a multilaboratory comparison organized by the consortium, agreement among nine laboratories that used their own optimized MIA was assessed on a panel of 15 reference sera for 13 pneumococcal serotypes with the new WHO standard 007sp. Agreement was assessed in terms of assay accuracy, reproducibility, repeatability, precision, and bias. The results indicate that the evaluated MIAs are robust and reproducible for measurement of vaccine-induced antibody responses. However, some serotype-specific variability in the results was observed in comparisons of polysaccharides from different sources and of different conjugation methods, especially for serotype 4. On the basis of the results, the consortium has contributed to the harmonization of MIA protocols to improve reliability of immune surveillance of Streptococcus pneumoniaeIMPORTANCE Serology of Streptococcus pneumoniae is challenging due to existence of multiple clinically relevant serotypes and the introduction of multivalent vaccines in national immunization programs. Multiplex immunoassays (MIAs) are applied as high-throughput cost-effective methods for serosurveillance, and yet laboratories use their own protocols. The aims of this study were to assess the agreement of results generated by MIAs in different laboratories within the EU Pneumo Multiplex Assay Consortium, to analyze factors contributing to differences in outcome, and to create a harmonized protocol. The study demonstrated good agreement of results of MIAs performed by laboratories using controlled assays for determination of levels of vaccine-induced pneumococcal antibodies. The EU Pneumo Multiplex Assay Consortium is open to everyone working in public health services, and it aims to facilitate efforts by participants to run and maintain a cost-effective, reproducible, high-quality MIA platform.
Assuntos
Anticorpos Antibacterianos/sangue , Imunoensaio/métodos , Infecções Pneumocócicas/epidemiologia , Infecções Pneumocócicas/microbiologia , Streptococcus pneumoniae/imunologia , Monitoramento Epidemiológico , Europa (Continente) , Humanos , Reprodutibilidade dos Testes , Sorogrupo , Streptococcus pneumoniae/classificaçãoRESUMO
BACKGROUND: Because IgM antibody against West Nile virus (WNV) pre-membrane/envelope (preM/E) recombinant protein may persist for more than 1 year, an assay distinguishing recent from past WNV infection would be useful. Published findings for a single patient suggest that the presence of antibody against WNV nonstructural protein 5 (NS5) indicates recent infection. OBJECTIVES: To compare the persistence of WNV NS5 antibodies and preM/E IgM using plasma samples from blood donors who were viremic at the time of donation. STUDY DESIGN: Follow-up plasma samples from 35 viremic donors were tested for WNV NS5 antibodies using a microsphere immunoassay, and compared to WNV preM/E IgM antibodies determined on the same samples using an enzyme-linked immunosorbent assay (ELISA). RESULTS: At 90+/-14 days of follow-up, 20/26 donors (77%) were positive for NS5 antibodies; 6/25 (24%) were positive at 180+/-27 days, and 3/23 (13%) were positive at 365+/-55 days. The comparable values for preM/E IgM antibodies were 77%, 32% and 17%, respectively. CONCLUSION: Persistence of WNV NS5 antibody in plasma is similar to that of preM/E IgM antibody. WNV NS5 antibody cannot be used to distinguish recent from past WNV infection.
Assuntos
Anticorpos Antivirais/sangue , Proteínas não Estruturais Virais/imunologia , Febre do Nilo Ocidental/imunologia , Vírus do Nilo Ocidental/imunologia , Ensaio de Imunoadsorção Enzimática , Imunofluorescência , Humanos , Imunoglobulina M/sangue , Microesferas , Fatores de Tempo , Proteínas do Envelope Viral/imunologiaRESUMO
Primary biliary cirrhosis (PBC) is an autoimmune disease of the liver characterized by progressive bile duct destruction eventually leading to cirrhosis and liver failure. The serological hallmark of the disease is the presence of circulating antimitochondrial antibodies (AMA). These reflect the presence of autoreactive T and B cells to the culprit antigens, the E2 subunits of mitochondrial 2-oxo-acid dehydrogenase enzymes, chiefly pyruvate dehydrogenase (PDC-E2). The disease results from a combination of genetic and environmental risk factors. Genetic predisposition is indicated by the higher familial incidence of the disease particularly among siblings and the high concordance rate among monozygotic twins. Environmental triggering events appear crucial to disrupt a pre-existing unstable immune tolerance of genetic origin allowing, after a long latency, the emergence of clinical disease. Initiating mimetopes of the vulnerable epitope of the PDC-E2 autoantigen can be derived from microbes that utilize the PDC enzyme or, alternatively, environmental xenobiotics/chemical compounds that modify the structure of native proteins to make them immunogenic. A further alternative as a source of antigen is PDC-E2 derived from apoptotic cells. In the effector phase the biliary ductular cell, by reason of its proclivity to express the antigen PDC-E2 in the course of apoptosis, undergoes a multilineage immune attack comprised of CD4(+) and CD8(+) T cells and antibody. In this article, we critically review the available evidence on etiopathogenesis of PBC and present interpretations of complex data, new developments and theories, and nominate directions for future research.
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Doenças Autoimunes/imunologia , Cirrose Hepática Biliar/imunologia , Animais , Apoptose/imunologia , Autoanticorpos/sangue , Doenças Autoimunes/genética , Doenças Autoimunes/patologia , Linfócitos B/imunologia , Ductos Biliares Intra-Hepáticos/imunologia , Citocinas/metabolismo , Modelos Animais de Doenças , Meio Ambiente , Células Epiteliais/imunologia , Predisposição Genética para Doença , Humanos , Imunidade Inata , Cirrose Hepática Biliar/genética , Cirrose Hepática Biliar/patologia , Fatores de Risco , Linfócitos T/imunologiaRESUMO
Published studies indicate that Candida albicans antibody assays utilizing cytoplasmic antigens offer greater utility for identifying cases of systemic candidiasis when compared with assays utilizing cell wall components. We assessed the performance characteristics of a commercially available system that utilizes cytoplasmic antigens to measure C. albicans IgG, IgM, and IgA (Candida Detect ELISA reagents). Intra-assay variation was < or =5%, inter-assay variation was < or =10%, and good linearity was observed for all the three antibody isotypes. Results for specimens stored under various conditions were comparable to those obtained initially. Inter-laboratory reproducibility was excellent; qualitative concordance was > or =93% for all the three isotypes, with slopes and R(2) values approaching 1.0 in linear regression analyses. Seroprevalence in persons without apparent systemic candidiasis was evaluated using three different serum panels; seroprevalence rates ranged from 24 to 32% for IgG, 2-14% for IgM, and 15-36% for IgA. Seroprevalence rates in a panel of sera containing antibodies to other fungi were similar to rates observed in panels from individuals without systemic candidiasis. These findings demonstrate the acceptable performance of assay systems employing Candida Detect ELISA reagents.
Assuntos
Anticorpos Antifúngicos/sangue , Candida albicans/imunologia , Candidíase/diagnóstico , Ensaio de Imunoadsorção Enzimática/métodos , California/epidemiologia , Candidíase/sangue , Candidíase/epidemiologia , Humanos , Imunoglobulina A/análise , Imunoglobulina G/análise , Imunoglobulina M/análise , Prevalência , Reprodutibilidade dos Testes , Estudos SoroepidemiológicosRESUMO
Clinical studies demonstrate differences in interferon-beta (IFNbeta) antibody detection frequencies among multiple sclerosis patients receiving different IFNbeta products. We sought to determine if these differences are also found when IFNbeta antibodies are measured in a reference laboratory, where factors normally controlled in clinical studies are unknown. Serum IFNbeta binding antibodies (BAbs) were quantitated by ELISA; BAbs-positive samples were then tested in a bioassay for neutralizing antibodies (NAbs). Consistent with clinical studies, frequencies of BAbs-positive sera and NAbs-positive sera were lower in the Avonex (IFNbeta-1a) treatment group than Rebif (IFNbeta-1a) and Betaseron (IFNbeta-1b) groups. We further identified a predictive relationship between positive BAbs levels and NAbs activity in patients treated with IFNbeta-1a products, but not those treated with IFNbeta-1b.
Assuntos
Anticorpos/análise , Anticorpos/imunologia , Bioensaio/métodos , Interferon beta/imunologia , Esclerose Múltipla/tratamento farmacológico , Anticorpos/sangue , Ensaio de Imunoadsorção Enzimática , Humanos , Interferon beta-1a , Interferon beta-1b , Valor Preditivo dos Testes , Ligação Proteica/imunologia , Sensibilidade e EspecificidadeRESUMO
Anti-MAG antibodies are commonly found in the sera of patients with demyelinating sensorimotor neuropathy and IgM paraproteinemia. Our objective here was to compare MAG results obtained by two different laboratories using similar methods (Western blot, EIA, IFA). Western blot (WB) employing MAG from monkey was less sensitive (72.5%) than myelin IFA (92.5%; monkey nerve) and EIA (97.5%; human MAG) when compared to WB using human MAG and is most likely due to methodology (not antigen source). EIA detected low titers of MAG IgM antibodies in suspected patient sera (negative by other methods) that were also SGPG IgM-positive. Patients having low titers by EIA, but negative by WB may have other autoimmune neuropathies without demyelination.
Assuntos
Autoanticorpos/metabolismo , Imunoglobulina M/metabolismo , Glicoproteína Associada a Mielina/imunologia , Adolescente , Adulto , Idoso , Animais , Especificidade de Anticorpos , Western Blotting/métodos , Feminino , Haplorrinos , Humanos , Técnicas Imunoenzimáticas , Masculino , Pessoa de Meia-IdadeRESUMO
All sera initially reactive in the Focus Diagnostics West Nile virus IgM capture enzyme-linked immunosorbent assay (WNV IgM ELISA) must be retested with background subtraction to identify falsely-reactive (FR) samples due to antibodies that bind to immunoglobulins of other animal species (heterophilic antibodies). In some settings, such as pre-transplant testing of organ donors, the reporting delay associated with retesting can have an adverse impact on donor procurement and organ placement. We sought to determine if inclusion of heterophilic antibody blockers in assay conjugate could eliminate the nonspecific reactivity of FR samples. Of 6 blocking reagents evaluated using a well-characterized FR sample, immunoglobulin inhibiting reagent from Bioreclamation (IIR) and blocker from Fitzgerald Industries (BFI) were superior in their ability to inhibit false reactivity; these 2 blockers were then used to evaluate 20 additional FR and 21 truly-reactive (TR) samples. Both blockers eliminated the reactivity of 20/21 FR samples, whereas all 21 TR samples remained reactive; further, all 13 truly non-reactive (NR) samples evaluated remained non-reactive when using blocker-containing conjugate. A subset of 22 samples were tested in parallel using the initial lot and a second lot of IIR and BFI; with one exception, all samples showed the same qualitative result using both lots of a given blocker. These findings demonstrate that modification of the Focus WNV IgM screening ELISA to include heterophilic antibody blocker IIR or BFI in assay conjugate eliminates the reactivity of most FR samples, markedly reducing the number of samples requiring further testing by background subtraction.