Immunoglobulin M Antibody Response Research Articles

Comparative analysis of SARS-CoV-2 detection methods using stool, blood, and nasopharyngeal swab samples.

as a public health policy, the ongoing global coronavirus disease 2019 vaccination drives require continuous tracking, tracing, and testing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Diagnostic testing is important in virus detection and understanding its spread for timely intervention. This is especially important for low-income settings where the majority of the population remains untested. This is well supported by the fact that of about 9% of the Kenyan population had been tested for the virus. this was a cross-sectional study conducted at the Kisumu and Siaya Referral Hospitals in Kenya. Here we report on the sensitivity and specificity of the rapid antigen detection test (Ag-RDT) of SARS-CoV-2 compared with the quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) using stool and nasopharyngeal swab samples. Further, the mean Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibody levels among symptomatic and asymptomatic individuals in western Kenya were evaluated. the sensitivity and specificity of Ag-RDT were 76.3% (95% CI, 59.8-88.6%) and 96.3% (95% CI, 87.3-99.5%) with a negative and positive predictive value of 85% (95% CI, 73.8%-93.0%) and 93% (95% CI, 78.6%-99.2%) respectively. There was substantial agreement of 88% (Kappa value of 0.75, 95% CI, 0.74-0.77) between Ag-RDT and nasopharyngeal swab RT-qPCR, and between stool and nasopharyngeal swab RT-qPCR results (83.7% agreement, Kapa value 0.62, 95% CI 0.45-0.80). The mean IgM and IgG antibody response to SARS-CoV-2 were not different in asymptomatic individuals, 1.11 (95% CI, 0.78-1.44) and 0.88 (95% CI, 0.65-1.11) compared to symptomatic individuals 4.30 (95% CI 3.30-5.31) and 4.16 (95% CI 3.32 -5.00). the choice of an appropriate SARS-CoV-2 diagnostic, screening, and surveillance test should be guided by the specific study needs and a rational approach for optimal results.

Understanding the dynamics of IgM & IgG antibodies in COVID-19-positive patients.

The pandemic caused by the SARS-CoV-2 has been a threat to humankind due to the rapid spread of infection and appearance of multiple new variants. In the present study, we report the dynamics and persistence of immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in asymptomatic and symptomatic COVID-19 patients by chemiluminescent assay. A total of 463 serum samples from 218 SARS-CoV-2 PCR-positive patients were collected over a period of 124 days post-onset of disease (POD). Antibody levels were measured by chemiluminescence bioanalyzer. Neutralizing antibody titres were assessed by plaque reduction neutralization test (PRNT) for SARS-CoV-2. Both IgM and IgG started appearing from day five post-infection in symptomatic and asymptomatic patients. IgM antibody response peaked around day 35 POD and rapidly diminished thereafter, with the last IgM-positive sample observed at 90 days POD. IgG antibody response peaked around 45 days POD and persisted till 124 days. The chemiluminescence immunoassay (CLIA) results showed a moderate correlation (R=0.5846, P<0.001) compared with PRNT. Additional analysis indicated a neutralizing titre of 250 corresponded to 12.948 AU/ml of YHLO iFlash SARS-CoV-2 IgG units. Both symptomatic and asymptomatic COVID-19 patients seem to initiate production of antibody responses from day five of onset of disease. Although the CLIA gives high sensitivity and specificity and also its binding IgG antibody titres may correlate moderately with protective immunity, our results indicate that the values of binding antibody alone may not be a perfect guide to represent virus neutralization titre during donor selection for plasma therapy. However, IgM and IgG antibody detection may help in monitoring the status of disease progression and burden in the community.

Antibody responses of Chlamydophila pneumoniae pneumonia: Why is the diagnosis of C. pneumoniae pneumonia difficult?

The ELNAS Plate Chlamydophila pneumoniae commercial test kit for the detection of anti-C. pneumoniae-specific immunoglobulin M (IgM), IgA and IgG antibodies has become available in Japan recently. To determine the optimum serum collection point for the ELNAS plate in the diagnosis of C.pneumoniae pneumonia, we analyzed the kinetics of the antibody response in patients with laboratory-confirmed C.pneumoniae pneumonia. We enrolled five C.pneumoniae pneumonia cases and collected sera from patients for several months. The kinetics of the IgM and IgG antibody responses were similar among the five patients. Significant increases in IgM and IgG antibody titer between paired sera were observed in all patients. IgM antibodies appeared approximately 2-3 weeks after the onset of illness, reached a peak after 4-5 weeks, and were generally undetectable after 3-5 months. IgG antibodies developed slowly for the first 30 days and reached a plateau approximately 3-4 months after the onset of illness. The kinetics of IgA antibody responses were different among the five patients, and significant increases in IgA antibody titer between paired sera were observed in only two patients. Although the sample size was small, the best serum collection time seemed to be approximately 3-6 weeks after onset of illness when using a single serum sample for the detection of IgM antibodies. Paired sera samples should be obtained at least 4 weeks apart. IgA antibody analysis using ELNAS may not be a useful marker for acute C. pneumoniae pneumonia.

IRAK-4 and MyD88 deficiencies impair IgM responses against T-independent bacterial antigens

AbstractIRAK-4 and MyD88 deficiencies impair interleukin 1 receptor and Toll-like receptor (TLR) signaling and lead to heightened susceptibility to invasive bacterial infections. Individuals with these primary immunodeficiencies have fewer immunoglobulin M (IgM)+IgD+CD27+ B cells, a population that resembles murine splenic marginal zone B cells that mount T-independent antibody responses against bacterial antigens. However, the significance of this B-cell subset in humans is poorly understood. Using both a 610 carbohydrate array and enzyme-linked immunosorbent assay, we found that patients with IRAK-4 and MyD88 deficiencies have reduced serum IgM, but not IgG antibody, recognizing T-independent bacterial antigens. Moreover, the quantity of specific IgM correlated with IgM+IgD+CD27+ B-cell frequencies. As with mouse marginal zone B cells, human IgM+CD27+ B cells activated by TLR7 or TLR9 agonists produced phosphorylcholine-specific IgM. Further linking splenic IgM+IgD+CD27+ B cells with production of T-independent IgM, serum from splenectomized subjects, who also have few IgM+IgD+CD27+ B cells, had reduced antibacterial IgM. IRAK-4 and MyD88 deficiencies impaired TLR-induced proliferation of this B-cell subset, suggesting a means by which loss of this activation pathway leads to reduced cell numbers. Thus, by bolstering the IgM+IgD+CD27+ B-cell subset, IRAK-4 and MyD88 promote optimal T-independent IgM antibody responses against bacteria in humans.

Relative Potency for Altered Humoral Immunity Induced by Polybrominated and Polychlorinated Dioxins/Furans in Female B6C3F1/N Mice

The use of brominated flame retardants and incineration of bromine-containing materials has lead to an increase in polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in the environment. Measurable amounts of PBDD/Fs have been detected in soil, seafood, and human breast milk and serum. Studies indicate that the relative potencies of some PBDD/Fs based on enzyme induction are equivalent to those of some polychlorinated dibenzo-p-dioxins and dibenzofurans. To assess the humoral immunity relative potencies of PBDD/Fs and compare them to their chlorinated analogs, female B6C3F1/N mice received a single oral exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrabromodibenzofuran (TBDF), 2,3,7,8-tetrachlorodibenzofuran (TCDF), 1,2,3,7,8-pentabromodibenzofuran (1PeBDF), 1,2,3,7,8-pentachlorodibenzofuran (1PeCDF), 2,3,4,7,8-pentabromodibenzofuran (4PeBDF), 2,3,4,7,8-pentachlorodibenzofuran (4PeCDF), 2,3-dibromo-7,8-dichlorodibenzo-p-dioxin (DBDCDD), or 2,3,7-tribromodibenzo-p-dioxin (TriBDD). Inhibition of the immunoglobulin M (IgM) antibody forming cell response was measured 4 days following immunization with sheep red blood cells. The data were fit to a Hill model to estimate the ED50 for inhibition. Expression of xenobiotic metabolizing enzyme (XME) and thyroxine transport protein (Ttr) genes in liver was measured by PCR to assess aryl hydrocarbon-mediated responses. TCDD, TBDF, TCDF, 1PeBDF, 4PeBDF, 4PeCDF, and DBDCDD suppressed the IgM antibody response and Ttr gene expression, and upregulated phase I XME genes. 1PeCDF suppressed the IgM antibody response but only upregulated phase I XME genes; TriBDD had no effect on antibody response. The rank order of potency (ED50) for these chemicals was TCDD>TBDF>4PeBDF>TCDF/4PeCDF/1PeBDF>1PeCDF. Whereas TCDD was the most potent compound tested, the brominated analogs were more potent than their chlorinated analogs, suggesting that these compounds should be considered in toxic equivalency factor evaluation and risk assessment.

Antiphospholipid IgM antibody response in acute and chronic Mycobacterium tuberculosis mouse infection model

The clinical management of tuberculosis (TB) could be greatly improved by an affordable biomarker test to monitor treatment response. Here, we examined changes in immunoglobulin M (IgM) antibody response to lipids as a potential biomarker for monitoring TB treatment in an experimental mouse model. We performed enzyme-linked immunosorbent assay to investigate changes in IgM antibody response against cardiolipin (CL), phosphatidylcholine (PTC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and sphingolipid (SL) in BALB/c mice that were treated after being infected with Mycobacterium tuberculosis for 4 weeks (acute infection) and 20 weeks (chronic infection). Cytokine levels [interleukin (IL)-5, IL-10, interferon-gamma (IFN-γ), monocyte chemoattractant protein-1 (MCP-1)] in lung and spleen homogenates as well as in blood were also compared. In both acutely and chronically infected mice, lungs were sterilised of M. tuberculosis infection after 8 weeks of treatment. The IgM response to CL, PTC, PE, PI and SL were consistently elevated throughout the course of infection in chronically infected mice compared with acutely infected mice. In acutely infected mice, the IgM antibody response against CL significantly decreased after 8 weeks of treatment, but not against other lipids. In chronically infected mice, the IgM response showed no significant changes against any of the lipids after 8 weeks of treatment. Of the cytokines examined, only MCP-1 levels in lungs decreased significantly after treatment. These findings demonstrate that antilipid IgM antibody can remain elevated in chronically infected mice, but with treatment, only anti-CL IgM antibody levels decreased together with M. tuberculosis bacterial burden in acutely infected mice. Treatment did not affect antilipid IgM levels in chronically infected mice.

Antenatal screening forToxoplasma gondiiinfection at a tertiary care hospital in Riyadh, Saudi Arabia

BACKGROUND AND OBJECTIVES:Congenital toxoplasmosis is associated with significant morbidity and mortality. This study investigates the prevalence of toxoplasmosis among pregnant women.DESIGN AND SETTING:A retrospective study at King Khalid University Hospital, Riyadh from September 2009 to August 2010.PATIENTS AND METHODS:Laboratory data of 2176 pregnant women screened for Toxoplasma gondii in the antenatal care unit were assessed during the study period. The mean (SD) age of the women and the duration of pregnancy were 25 (7.3) years and 18 (7.7) weeks, respectively. Data were extracted for the presence or absence of anti-T gondii immunoglobulin G (IgG) and IgM antibodies.RESULTS:Of 2176 sera tested, 1351 (62%) did not show any evidence of exposure to T gondii. The remaining 825 (38%) samples tested positive for anti-T gondii IgG antibodies, and none was found to have anti-T gondii IgM antibodies in the serum. These data reveal that a significantly high number of women in the antenatal care unit at King Khalid University Hospital in Riyadh had been exposed to T gondii.CONCLUSION:A high prevalence of toxoplasmosis among pregnant women warrants multicenter community-based investigations for assessment of T gondii infection and identification of risk factors for transmission of toxoplasmosis in general, and particularly during pregnancy.

Generation of Antibody Responses to Pneumococcal Capsular Polysaccharides Is Independent of CD1 Expression in Mice

Streptococcus pneumoniae is a bacterial microorganism that frequently causes serious infection, particularly in children and the elderly. Protection against infection with S. pneumoniae is based mainly on the generation of antibodies to the pneumococcal capsular polysaccharides (caps-PS), but the mechanisms responsible for the generation of anticapsular antibodies remain incompletely understood. The aim of the present study was to evaluate the role of CD1-restricted T cells in the antibody response to caps-PS. When immunized with Pneumo23, wild-type mice and CD1 knockout mice on BALB/c and C57BL/6 backgrounds generated immunoglobulin M (IgM) and IgG antibody responses to soluble caps-PS that were comparable. Similar results were obtained after immunization with heat-inactivated S. pneumoniae. The IgM and IgG antibody response of wild-type mice to Pneumo23 was not affected by an antagonizing monoclonal anti-CD1 antibody treatment. In summary, our data provide evidence that the antibody response to caps-PS is generated independently of CD1 expression.

Naturally Acquired IgM Antibody Response to the C-Terminal Region of the Merozoite Surface Protein 1 of Plasmodium vivax in Korea: Use for Serodiagnosis of Vivax Malaria

The antibody levels against the C-terminal region of the merozoite surface protein 1 of Plasmodium vivax (PvMSP1c) were measured in 276 patients with P. vivax malaria (patient group), 320 malaria-naïve healthy individuals (control group 1), and 70 malaria-naïve individuals with various disorders (control group 2) using the immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) and the direct sandwich ELISA. To evaluate the antibody response during relapse, 5 relapsed patients were tested using the IgM capture ELISA. The IgM antibodies were negative in 99.7% of control group 1 and in 100% of control group 2; they were positive in 90.6% of the patient group. The total antibody levels were positive in 88.4% of the patient group with the direct sandwich ELISA. The sera from the second malaria episode, i.e., relapsed patients, were 100% positive on the IgM capture ELISA. The results of this study suggest that the IgM capture ELISA may be a useful diagnostic method for P. vivax malaria for both primary infection and relapse.

Chemical Exposures: Not Immune to PFOS Effects?

Two recent studies have demonstrated that exposure to perfluorooctanyl sulfonate (PFOS) can alter mammalian immune system function. In one study, PFOS induced immunotoxicity in test animals at exposures analogous to those reported in the U.S. population, raising the possibility that “if humans and mice share similarities in their immune systems, then people today could be immunocompromised due to current PFOS exposure,” says Jennifer Keller, a research biologist at the National Institute of Standards and Technology’s Hollings Marine Laboratory. However, resolving this question will require carefully controlled epidemiologic studies that include relevant immune system and infectious disease end points. PFOS was removed from 3M’s Scotchgard™ stain repellent by the end of 2002, but the compound degrades slowly and is dispersed widely throughout the environment. Data from the National Health and Nutrition Examination Survey 2003–2004 documented that it was found in 99.9% of samples. Research slated for publication in the 1 July 2008 issue of Toxicological Sciences documents that production of the immunoglobulin M (IgM) antibody decreased in B6C3F1 mice exposed to PFOS. This suggests the immune response to pathogens may be suppressed and could result in increased disease susceptibility, says lead author Margie Peden-Adams, a research assistant professor at the Medical University of South Carolina. She says these effects occurred at serum PFOS levels (91.5 ppb in male mice) that were 14 times lower than the average blood concentrations of occupationally exposed humans and in the upper range of concentrations reported for the general population, making this the lowest reported lowest-observable-effect level for PFOS. She adds that suppression of IgM production in female mice occurred at dose concentrations 10 times higher than in males. The male mice’s natural killer (NK) cell population, an important part of the innate immune system for tumor and viral surveillance, was increased, but female NK cell function was not affected. Peden-Adams speculates that the increase could be a compensation for a decrease in the male mice’s populations of cytotoxic T cells, which also have functions related to killing tumor cells. Additional testing determined that the cause of the decreased IgM production is probably an issue with B cells, the cell type that differentiates into antibody-producing cells, she says. Another study, published 1 May 2008 in Toxicological Sciences by Deborah Keil, an associate professor of clinical laboratory sciences at the University of Nevada at Las Vegas, also linked a reduction in IgM antibody response to PFOS exposure. This study, which evaluated the immune systems of B6C3F1 mouse pups whose mothers were exposed to the compound during pregnancy, showed that NK cell function was decreased in male pups. Both studies document that PFOS targeted antibody production and that males appeared more sensitive than females to the effects of PFOS, Keil says. Peden-Adams says her group was quite surprised by their findings and that further research is needed to determine the effects’ mode of action in order to determine human risk. Her paper posits that sex differences in sensitivity may be related to levels of estrogen and testosterone, because these steroids are known to affect immune system function. “We know that PFOS does have some endocrine-disrupting activity,” she says, adding that some research suggests the chemical may be antiestrogenic. A third study using a different mouse strain found similar effects for perfluorooctanoic acid (PFOA). The study, published in the May 2008 issue of EHP by research biologist Robert Luebke of the U.S. Environmental Protection Agency National Health and Environmental Effects Research Laboratory, showed that adult female C57BL/6J mice exposed to higher concentrations of PFOA also exhibited a reduction in IgM production.

Specific Intracellular Adhesion Molecule-Grabbing Nonintegrin R1 Is Not Involved in the Murine Antibody Response to Pneumococcal Polysaccharides

Streptococcus pneumoniae is a microorganism that frequently causes serious infections in children, the elderly, and immunocompromised patients. We studied whether the specific intracellular adhesion molecule-grabbing nonintegrin R1 (Sign-R1) receptor, involved in the uptake of capsular polysaccharides (caps-PS) by antigen-presenting cells, is necessary for the antibody response to pneumococcal caps-PS and phosphorylcholine (PC). The antibody response to caps-PS and PC was evaluated after vaccination with soluble caps-PS (Pneumovax) and after vaccination with heat-killed S. pneumoniae. The role of Sign-R1 was investigated by using Sign-R1 knockout mice and anti-Sign-R1 monoclonal antibodies. The immunoglobulin M (IgM) and IgG antibody response to PC and caps-PS (serotypes 3 and 14) was not affected by anti-Sign-R1 monoclonal antibodies. The IgM antibody response in Sign-R1 knockout mice was comparable to the antibody response in wild-type mice. The IgG antibody response to serotype 3, but not to serotype 14, tended to be lower in Sign-R1 knockout mice compared to wild-type mice. In conclusion, we found that Sign-R1 is not involved in the IgM antibody production to PC and caps-PS serotype 3 or 14 and the IgG immune response to PC and caps-PS serotype 14. There is no direct relation between capture and uptake of caps-PS serotype 14 by Sign-R1 and the initiation of the anti-caps-PS antibody production in mice.

Vaccination-relatedMycobacterium bovisBCG Infection

Vaccination-related<i>Mycobacterium bovis</i>BCG Infection

Characterization of Acute-Phase Humoral Immunity to Monkeypox: Use of Immunoglobulin M Enzyme-Linked Immunosorbent Assay for Detection of Monkeypox Infection during the 2003 North American Outbreak

A monkeypox outbreak occurred in the United States in 2003. Patient's sera were sent to the Centers for Disease Control and Prevention as a part of outbreak response measures. Clinical and epidemiologic information was abstracted from the case investigation forms. Serum samples from patients were tested by using an immunoglobulin M (IgM)-capture and an IgG enzyme-linked immunosorbent assay ELISA against Orthopoxvirus antigen. The detection of antiviral IgG and IgM antibodies and the kinetics of the antiviral IgG and IgM antibody responses were evaluated. Patients were classified as confirmed, probable, or suspect cases or were excluded as cases based on laboratory test results and epidemiologic and clinical criteria. A total of 37 confirmed case patients with monkeypox were identified, and 116 patients were excluded as case patients based on molecular testing or insufficient epidemiology and clinical data to warrant classification as a suspect or probable case. Of 37 confirmed case patients, 36 had a known history (presence or absence) of smallpox vaccination. Of those, 29 of the 36 either had or developed an IgG response, while 34 of the 36 developed an IgM response, regardless of vaccination status. Serum collected > or =5 days for IgM detection or serum collected > or =8 days after rash onset for IgG detection was most efficient for the detection of monkeypox virus infection. IgM ELISA detects recent infection with orthopoxviruses and, in this case, recent infection with monkeypox virus. In addition, analysis of paired sera for IgG and IgM detected seroconversion, another indicator of recent infection. The ELISA results correlated with the virologic PCR and viral culture results, indicating its diagnostic capabilities for monkeypox and potentially other orthopoxvirus infections due to zoonotic transmission or bioterrorism events.

Borreliacidal OspC Antibodies Specific for a Highly Conserved Epitope Are Immunodominant in Human Lyme Disease and Do Not Occur in Mice or Hamsters

Humans produce highly specific borreliacidal antibodies against outer surface protein C (OspC) shortly after infection with Borrelia burgdorferi sensu stricto. We previously demonstrated the epitope recognized by immunoglobulin M (IgM) and IgG OspC borreliacidal antibodies was located within the 50 amino acids nearest the carboxy (C) terminus. In this study, we show the immunodominant epitope is located in the highly conserved region within the seven C-terminal amino acids. Six early Lyme disease sera that contained borreliacidal activity and IgM and/or IgG OspC antibodies were chosen randomly and adsorbed with truncated OspC containing the 16 or 7 amino acids nearest the C terminus. Adsorptions with each truncated protein abrogated the borreliacidal activity completely. In addition, only small concentrations of OspC antibodies remained detectable by enzyme-linked immunosorbent assay and Western blotting. Moreover, borreliacidal OspC antibodies were not induced in laboratory mice or hamsters despite heavy infections with B. burgdorferi spirochetes. These findings confirm that borreliacidal antibodies comprise the majority of the IgM and IgG OspC antibody response in human Lyme disease and that the epitope is located in the highly conserved C terminus. In addition, rodent animal models appear to be inappropriate subjects for assessing the effectiveness of the epitope for serodiagnosis or as a human Lyme disease vaccine.

B-Cell and T-Cell Immune Responses to ExperimentalHelicobacter pyloriInfection in Humans

The acute antibody and T-cell immune response to Helicobacter pylori infection in humans has not been studied systematically. Serum from H. pylori-naive volunteers challenged with H. pylori and cured after 4 or 12 weeks was tested by enzyme-linked immunosorbent assays for anti-H. pylori-specific immunoglobulin M (IgM) and IgA established using bacterial lysates from homologous (the infecting strain) and heterologous H. pylori. Proteins recognized by IgM antibody were identified by mass spectrometry of immunoreactive bands separated by two-dimensional gel electrophoresis. Mucosal T-cell subsets (CD4, CD8, CD3, and CD30 cells) were assessed by immunohistochemistry. All 18 infected volunteers developed H. pylori-specific IgM responses to both homologous or heterologous H. pylori antigens. H. pylori antigens reacted with IgM antibody at 4 weeks postinfection. IgM Western blotting showed immunoreactivity of postinfection serum samples to multiple H. pylori proteins with molecular weights ranging between 9,000 (9K) to 150K with homologous strains but only a 70K band using heterologous antigens. Two-dimensional electrophoresis demonstrated that production of H. pylori-specific IgM antibodies was elicited by H. pylori flagellins A and B, urease B, ABC transporter binding protein, heat shock protein 70 (DnaK), and alkyl hydroperoxide reductase. Mucosal CD3, CD4, and CD8 T-cell numbers increased following infection. IgM antibody responses were detected to a range of homologous H. pylori antigens 2 to 4 weeks postchallenge. The majority of H. pylori proteins were those involved in motility and colonization and may represent targets for vaccine development.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) alters the regulation of Pax5 in lipopolysaccharide-activated B cells.

The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) produces a profound suppression of the primary immunoglobulin-M (IgM) antibody response. The suppression of IgM production by TCDD can occur through direct interactions with the B cell, is aryl hydrocarbon receptor-dependent, and is mediated through alterations in the differentiation of B cells into plasma cells. The objective of the present investigation was to characterize the effects of TCDD on the regulation of Pax5, a crucial repressor of B-cell differentiation, and four downstream targets that are directly regulated by Pax5 and involved in immunoglobulin regulation, immunoglobulin heavy chain (IgH), kappa light chain (Igkappa), J chain, and X box protein-1 (XBP-1). Lipopolysaccharide (LPS) activation of aryl hydrocarbon receptor-expressing CH12.LX cells induced B cell differentiation and robust immunoglobulin secretion that was markedly (~50%) suppressed in the presence of 10 nM TCDD. Kinetic studies show that LPS-activation induced a time-dependent decrease in Pax5 mRNA levels, protein, and DNA binding activity during a 72-h culture period that was almost completely blocked in the presence of TCDD. Concomitant with the time-dependent down-regulation of Pax5 in LPS-activated control CH12.LX cells, a reciprocal induction of IgH, Igkappa, J chain mRNA levels, and cellular XBP-1 was observed. Conversely, and consistent with the absence of Pax5 down-regulation associated with TCDD treatment, IgH, Igkappa, J chain mRNA, and XBP-1 protein were persistently repressed in LPS-activated CH12.LX cells. Collectively, these studies demonstrate the involvement of altered Pax5 regulation in the suppression of the primary IgM antibody response by TCDD.

Measles virus-specific immunoglobulin G isotype immune response in early and late infections.

A total of 154 human serum samples (32 acute-phase and 22 convalescent-phase serum samples obtained within a week and between days 8 and 26 after the onset of rash, respectively, and 100 samples drawn from healthy immune adults) were processed by an immunofluorescence assay for the detection of immunoglobulin M (IgM), total immunoglobulin G (IgG), IgG1, IgG2, IgG3, and IgG4 measles virus-specific antibodies. In the acute phase, IgG1 was seen first, followed by IgG2, IgG3, and IgG4 responses, the mean seropositivity of which gradually increased during convalescence, reaching 100% (standard deviation [SD], 84 to 100%), 57% (SD, 34 to 80%), 86% (SD, 66 to 100%), and 86% (SD, 66 to 100%), respectively. IgG2 rose and fell in connection with IgG3 subclass antibodies, showing a rate of detection of IgG2 and/or IgG3 subclass antibodies of 95.5% (range, 100 to 86.5%) in the convalescent phase of infection. The mean percentage of measles IgG2 and IgG3 seropositivity dropped significantly during the memory phase, to 2% (range, 2 to 6%) and 3% (range, 3 to 7%), respectively (P < 0.05); meanwhile IgG1 and IgG4 subclass responses remained relatively unmodified in samples obtained years after infection (mean 100% [SD, 96 to 100%] and 86% [SD, 79 to 93%], respectively). Results obtained defined two highly different immune isotypic response patterns. One pattern is restrictive to IgG2 and/or IgG3 in the convalescent phase and is kinetically similar to the IgM antibody response, so its detection could be referred to as a recent viral activity. On the other hand, IgG1 and IgG4 were detected in both the convalescent and memory phases of the immune response, but their isolated occurrence without IgG2 and IgG3 could be related to the long-lasting immunity.

Measurement of antibodies against meningococcal capsular polysaccharides B and C in enzyme-linked immunosorbent assays: towards an improved surveillance of meningococcal disease.

In order to improve the surveillance of serogroup B and C meningococcal diseases, enzyme-linked immunosorbent assays (ELISAs) specific for anti-B immunoglobulin M (IgM) and anti-C IgM and IgG antibodies were developed. The tests were evaluated by using paired sera from 122 patients with and 101 patients without laboratory evidence of meningococcal disease. Fifty-three of 67 patients (79%) with culture-confirmed serogroup B disease had an anti-B IgM antibody response; anti-B IgM levels waned rapidly in children < or = 4 years of age. Twenty-four of 25 patients (96%) with culture-confirmed serogroup C disease had an anti-C IgM and/or IgG antibody response (IgM, 92%; IgG, 68%). In patients without evidence of meningococcal disease, 19% of children < or = 4 years of age and 69% of those > 4 years of age had intermediate anti-B IgM titers. In contrast, only 1 and 5% of these patients had intermediate titers of anti-C IgM and anti-C IgG, respectively. The ELISAs were shown to be powerful tools for discriminating between serogroup B and C diseases in 96 to 100% of culture-confirmed cases. For 90% of patients with culture-negative meningococcal disease, a serogroup-specific diagnosis could be established by examination of paired sera in the ELISAs. As serogroup B and C meningococci account for practically all cases of meningococcal disease in industrialized countries, the availability of these tests may improve surveillance and prevention.

Comparative evaluation of immunoglobulin M neutralizing antibody response in acute-phase sera and virus isolation for the routine diagnosis of enterovirus infection

A total of 314 patients exhibiting symptoms consistent with a viral disease provided, during the early stage of hospitalization, at least one specimen from a peripheral site (throat or stools or both) and a serum specimen in order to evaluate the neutralizing immunoglobulin M (IgM) antibody response in acute-phase serum in comparison with virus isolation for the rapid diagnosis of enterovirus (EV) infection. IgM antibodies were fractionated by ion-exchange chromatography and tested by seroneutralization against the various types of EV that have been recently circulating. A total of 189 patients (60%) were negative, and 21 (7%) were positive by both methods; in 51 patients (16%), a virus was isolated without IgM antibody response; 53 patients (17%) showed the opposite pattern. In all age groups except for children under 6 months, the frequency of positive results was higher with IgM serology than with virus isolation (27 and 22%, respectively). Apart from meningitis, for which isolation was more efficient, the other clinical conditions were associated with similar percentages of positivity by both methods. Regarding the 21 cases with positive results by the two techniques, the same serotype was detected in 9 cases and different serotypes were detected in 12, suggesting crossreactivities. Thus, IgM neutralizing antibody response on acute-phase serum appears to be of limited value in the rapid diagnosis of acute EV infection but may prove useful for the investigation of the wide range of chronic diseases associated with EV.

Detection of Bovine Herpesvirus-1-Specific IgM Using a Capture Enzyme Immune Assay with Isotype-Specific Monoclonal Antibodies

The detection of virus-specific immunoglobulin M (IgM) antibodies in acute-phase serum samples offers the possibility of making an accurate and rapid serologic diagnosis. We have developed a solid-phase capture assay that uses murine monoclonal antibodies specific for bovine IgM to separate the whole IgM fraction of a bovine serum sample. The IgM specific for bovine herpesvirus-1 (BHV-1) is then detected by the addition of viral antigen, which in turn is detected by BHV-1-specific monoclonal antibodies conjugated to horseradish peroxidase. A BHV-1 IgM antibody response was detected during the early postinfection period (7-40 days PI). Bovine herpesvirus-1 IgM antibody was not detected in sera taken from 3 animals following dexamethasone-induced viral reactivation. This method compares favorably with viral isolation, antigen detection in the clinical samples, and paired serology in the diagnosis of BHV-1 infection at a herd level.