Development of a second generation anti-Müllerian hormone (AMH) ELISA

AMH is a glycoprotein dimer composed of two 72kDa monomers linked by disulfide bridges. It belongs to the transforming growth factor-β family. AMH performs various physiological functions. In males, AMH is secreted by the Sertoli cells of the testis. During embryonic development, AMH is responsible for Müllerian duct regression. AMH continues to be produced by the testicles until puberty and then decreases slowly to residual post-puberty values. In females, AMH is produced in small amounts by ovarian granulosa cells after birth, until menopause, and then becomes undetectable. A two-step, sandwich-type enzymatic microplate assay has been developed to measure AMH levels in 20 μL of sample in less than 3h. AMH calibrators range from 0.2 to 28 ng/mL. The antibodies used in the assay bind to the mature region of AMH, which is more stable to proteolysis compared to prohormone region. The AMH Gen II assay (Beckman Coulter, Inc., Webster, Texas) was standardized to the Immunotech (IOT, Beckman Coulter, Inc., Marseilles, France) AMH assay. AMH Gen II, when compared to IOT using 120 serum samples in the range of 0-20.4 ng/mL yielded a correlation coefficient of 0.98 and a slope of 1.0. Total imprecision, calculated on four samples over 40 runs, four replicates per run, between two lots using CLSI EP5-A guidelines, was 5.7% at 3.8 ng/mL, 7.7% at 4.4 ng/mL, 5.8% at 14 ng/mL and 5.3% at 16.4 ng/mL. The average analytical sensitivity calculated by the interpolation of the mean plus two standard deviations of 16 replicates of the zero calibrator on two independent lots was 0.08ng/mL. Dilution and spiking studies showed an average recovery of 91-110%. Lot-to-lot comparison of two independent lots testing 38 serum samples (1.5-33 ng/mL range) yielded a slope of 1.01, intercept of -0.08 ng/mL and r of 0.99. When potential interferents (hemoglobin, triglycerides, and bilirubin) were added at two times the physiological concentrations, AMH concentrations were within ± 10% of the control. A highly specific and reproducible microplate AMH Gen II assay has been developed to standardize the measurement of AMH between methods. The performance of the AMH Gen II assay is ideal for investigation into the physiologic roles of AMH in men and women.

Development of a second generation Inhibin B ELISA

Inhibins are heterodimeric protein hormones secreted by the granulosa cells of the ovary in the female and the Sertoli cells of the testis in the male. Published research studies have assessed Inhibin B levels in Sertoli cell function, ovarian reserve and granulosa cell tumors. A two-step sandwich-type enzymatic microplate assay to measure Inhibin B levels within 3.5h is reported, and sample pre-treatment is not required. The assay measures Inhibin B in 50 μL of serum or Li-Hep plasma sample against Inhibin B calibrators (10-1000 pg/mL). The highly characterized antibody pair used in the assay measures 100% Inhibin B and no response was detected above the sensitivity of the assay with Inhibin A, Activin A, Activin B, Activin AB, AMH, FSH, LH or Follistatin 315 at the concentrations tested. The second generation Inhibin B assay was compared against two commercially available assays using 60 male and 60 female samples, ranging in age from 20 to 50 years. The assay showed significant positive linear correlations to Oxford Brooks Innovation (OBI) and Diagnostics Systems Laboratories (DSL) assays (r=0.99; P<0.0001; and r=0.97; P<0.0001), respectively. Method comparison to OBI and DSL resulted in the following slope and intercept (Gen II=1.03 OBI-6.77 pg/mL and Gen II=1.57 DSL+11.29 pg/mL), respectively. Matched serum and Li-Hep plasma samples (n=120) showed a correlation coefficient of >0.99 and a slope of 0.97 with zero intercept. Total imprecision calculated on three samples and two controls over 40 runs, three replicates per run, using NCCLS EP5-A guidelines was 6.8% at 19.34 pg/mL, 4.4% at 76.03 pg/mL, 4.3% at 275.3 pg/mL, 5.4% at 99.88 pg/mL, and 5.7% at 363.9 pg/mL. The LoQ for the assay at 20% CV was 4.8 pg/mL. Dilution and spiking studies showed an average recovery of 90-110%. A highly specific, sensitive, simplified and reproducible microplate Inhibin B assay has been developed to measure Inhibin B in serum and Li-Hep plasma. The performance of the assay is ideal for investigation into the physiologic role of Inhibin B in both men and women.

Immunoassay for quantifying squamous cell carcinoma antigen in serum

BACKGROUND

Although the benefits of quantifying serum squamous cell carcinoma antigen (SCCa) have been reported, SCCa reagents were no longer available in the US by the late 1990s. Because SCCa quantification still has demonstrated clinical utility, we developed and validated a microtiter plate-based ELISA for measuring SCCa in serum.

METHODS

We coated microtiter strips overnight with capture anti-SCCa monoclonal antibody, washed the wells, added blocking buffer, and lyophilized the strips. For detection, we used a biotinylated anti-SCCa detection antibody, streptavidin/horseradish peroxidase conjugate, and tetramethylbenzidine/H(2)O(2) substrate. A novel blocking reagent against human antimouse antibodies (HAMA) was evaluated. A reference interval was established with sera from healthy individuals and was confirmed in smokers.

RESULTS

The assay was linear to 40 microg/L SCCa (slope, 1.00; y intercept, 0.695; R(2), 0.996) with a detection limit of 0.3 microg/L. The intraassay imprecision results [mean (CV)] were 2.5 microg/L (3.4%), 18.0 microg/L (3.0%), and 30.7 microg/L (2.4%); interassay imprecision results were 2.0 microg/L (9.9%), 20.0 microg/L (7.6%), and 36.3 microg/L (3.5%). A correlation analysis against an established automated assay generated a slope of 0.976 and a y intercept of -0.193 microg/L (r(2) = 0.916). An upper reference limit of 2.1 microg/L SCCa was established at 95% confidence level, with no difference observed in smokers. No correlation between SCCa concentration and age was observed (r(2) = 0.0003). At a blocking reagent concentration of 5 mg/L, HAMA interference was eliminated in 3 samples known to produce falsely increased SCCa results.

CONCLUSIONS

This SCCa ELISA demonstrates acceptable performance characteristics for quantifying serum SCCa and is effective in eliminating HAMA interference.

Spurious hypercalcitoninemia in patients with nodular thyroid disease induced by heterophilic antibodies

BACKGROUND

Serum calcitonin is the most useful tumor marker for the diagnosis and follow-up of medullary thyroid carcinoma (MTC). Spurious hypercalcitoninemia caused by heterophilic antibody interference (HAI) is rarely found in patients without MTC.

METHODS

We studied 2 patients with hypercalcitoninemia and thyroid nodules, but no evidence of MTC on fine-needle aspiration cytology. We performed calcium stimulation tests, measured serum calcitonin with another calcitonin kit, performed dilution tests, and remeasured serum calcitonin after applying heterophilic blocking tubes.

RESULTS

In a 31-year-old woman with no response to the calcium stimulation test, serum calcitonin was <5 pg/mL using another kit. After we applied heterophilic blocking tubes, the serum calcitonin level decreased to normal range. We concluded that patient had spurious hypercalcitoninemia. In a 63-year-old woman, all tests revealed that the patient had true hypercalcitoninemia. The patient underwent total thyroidectomy that revealed MTC.

CONCLUSIONS

We suggest that patients suspected for spurious hypercalcitoninemia should undergo further investigation due to HAI.

Prevalence and isotypic complexity of the anti-Chinese hamster ovary host cell protein antibodies in normal human serum

Host cell-derived protein impurities may be present at low levels in biopharmaceutical products. Antibodies to host cell proteins are present in individuals with no known exposure to these products. In this study, antibodies to drug process-specific Chinese hamster ovary host cell-derived proteins (CHO-HCP) were measured in unexposed individuals using a validated enzyme-linked immunosorbent assay. Samples that tested positive for anti-CHO-HCP reactivity were further characterized to determine the isotypes and IgG subclasses expressed in each positive individual. The specificity of the detected anti-CHO-HCP antibody isotypes was confirmed by the competitive inhibition assay and the uncoated plate specificity testing. These antibody characterization experiments revealed that the prevalent anti-CHO-HCP antibody subclasses were predominantly IgG1 (present in 66.6% of individuals) and IgG2 (60%), with 33.3% positive for IgG3 while IgG4 was detected in low abundance. Forty percent (40%) of the individuals with IgG type reactivity were also identified as IgM-positive. Anti-CHO-HCP-specific IgE was not detected in the assays used in this study. Some individuals exhibited single isotype anti-CHO-HCP reactivity; others contained a combination of multiple antibody isotypes. Data presented in this study demonstrate the isotypic complexity and the high prevalence of anti-CHO-HCP antibodies in human serum with no known exposure to CHO cell-derived therapeutic biologics.

IgY: a promising antibody for use in immunodiagnostic and in immunotherapy

Immunoglobulin IgY is the major antibody produced by chickens (Gallus domesticus). After their V-C gene is rearranged in B cells, IgY is continually synthesized, excreted into the blood and transferred to the egg yolk, where it is accumulated. IgY is produced by hens to provide their offspring with an effective humoral immunity against the commonest avian pathogens until full maturation of their own immune system. In this review we aim to give an overview about the generation, structure, properties of IgY, as well as the advantages of chicken antibodies use over mammalian antibodies in immunodiagnostics and immunotherapy.

Prevalence of human anti-mouse antibodies (HAMAs) in routine examinations

BACKGROUND

Circulating heterophilic antibodies interfere with immunological assays in laboratory examinations; however, their rate of incidence is currently questionable. We developed an enzyme-linked immunosorbent assay (ELISA) to detect human anti-mouse antibodies (HAMAs) in routine examinations.

METHODS

The study samples were comprised of serum samples obtained from 290 inpatients and outpatients at our hospital. Mouse immunoglobulin G1 (mIgG1), mIgG2a, and mIgG2b were used as the antigens and horseradish peroxidase (HRP)-conjugated anti-human IgG and IgM were used to identify the HAMA isotype.

RESULTS

HAMAs were detected in 11.7% (34/290) of the samples. We observed 18 and 20 samples positive for IgG- and IgM-type HAMAs, respectively. Four samples contained both IgG- and IgM-type HAMAs. HAMAs against mIgG1, mIgG2a, and mIgG2b were found in 21, 14, and 13 samples, respectively. Existence of HAMAs was confirmed by western blotting using mIgG's as the antigens and HAMAs as the primary antibodies. Heterophilic blocking reagent (HBR) was also used to block the heterophilic interactions. Unexpectedly, a low HBR concentration rather enhanced the interactions instead of blocking them.

CONCLUSIONS

A considerable number of HAMA-positive samples, reacting with the heavy chain of mIg, were found in routine examinations. A sufficient amount of HBR should be used for blocking the heterophilic interactions.

A new 'total' activin B enzyme-linked immunosorbent assay (ELISA): development and validation for human samples

BACKGROUND AND OBJECTIVE

There are currently no sensitive and specific assays for activin B that could be utilized to study human biological fluids. The aim of this project was to develop and validate a 'total' activin B ELISA for use with human biological fluids and establish concentrations of activin B in the circulation and fluids from the reproductive organs.

DESIGN

The new ELISA was validated and then used to measure activin B levels in the circulation of healthy participants, IVF patients, pregnant women and in ovarian follicular fluid and seminal plasma.

PATIENTS AND MEASUREMENTS

Healthy adult subjects (n = 143), subjects from an IVF clinic (n = 27) and pregnancy groups (n = 29) were sampled.

RESULTS

The sensitivity of the assay was 0.019 ng/ml. Validation of the activin B ELISA showed good recovery (90.7 +/- 9.8%) and linearity in biological fluid and cell culture media and low cross-reactivity with related analytes (inhibin B = 0.077% and activin A = 0.0034%). There was a negative correlation between activin B concentration (r = -0.281, P < 0.011) and females with increasing age. Patients attending IVF clinics had significantly lower levels of activin B compared with gender-matched control subjects. Ovarian follicular fluid and seminal plasma had 50-80 fold higher levels of activin B (mean = 5.35 and 3.66 ng/ml respectively) than sera (mean = 0.071 ng/ml).

CONCLUSIONS

This fully validated ELISA for activin B offers a tremendous utility for measuring this protein in a variety of normal physiological processes and in various clinical pathologies.

Elimination of false-positive results in a luminex assay for pneumococcal antibodies

In our 14-valent Luminex assay for pneumococcal antibodies, we identified two groups of sera that caused false-positive results. The first group bound nonspecifically to the Luminex microspheres. The second group reacted specifically with bovine serum albumin (BSA). We describe here methods that eliminated the false-positive reactivity of both groups.

Gender differences in correlates of troponin assay in diagnosis of myocardial infarction

Cardiac troponins are the most sensitive and specific biomarker for myocardial infarction (MI) diagnosis. If there is a gender bias in MI diagnosis, it could be reduced by more consistently applying objective diagnostic criteria to improve women's outcomes. This study set out to assess the accuracy and correlates of the cardiac troponin I (cTnI) assay in the diagnosis of non-ST-segment elevation MI, to determine how the assay accuracy and correlates vary by gender, and to explore the interaction between factors that may influence cTnI accuracy and affect gender differences in diagnosis. The data were obtained from the CHECKMATE study. It included 924 patients with possible myocardial ischemia excluding subjects with ST-segment elevation. The Dade-Behring Stratus CS STAT near-patient instrument (Dade Behring, Inc, Newark, Del) was used to measure cTnI. We assessed baseline troponin accuracy using a standard MI definition. There were 125 subjects with a definite MI diagnosis. Baseline troponin was 44% sensitive and 97% specific in predicting MI, with no significant gender differences. In contrast, other positive cardiac markers, namely rising or falling creatine-kinase MB fraction and positive electrocardiogram, occurred more frequently in men. Sensitivity (SE) of baseline troponin was higher in subjects where baseline troponin was obtained longer than 2 hours after the chest pain onset. The study did not observe a significant difference in the assay SE or specificity by gender. This observation, plus the fact that other positive cardiac markers occurred more frequently in men, suggest the troponin test may help to improve the diagnosis of MI in women.

Nanoparticle-based bio-barcode assay redefines "undetectable" PSA and biochemical recurrence after radical prostatectomy

We report the development of a previously undescribed gold nanoparticle bio-barcode assay probe for the detection of prostate specific antigen (PSA) at 330 fg/mL, automation of the assay, and the results of a clinical pilot study designed to assess the ability of the assay to detect PSA in the serum of 18 men who have undergone radical prostatectomy for prostate cancer. Due to a lack of sensitivity, available PSA immunoassays are often not capable of detecting PSA in the serum of men after radical prostatectomy. This new bio-barcode PSA assay is approximately 300 times more sensitive than commercial immunoassays. Significantly, with the barcode assay, every patient in this cohort had a measurable serum PSA level after radical prostatectomy. Patients were separated into categories based on PSA levels as a function of time. One group of patients showed low levels of PSA with no significant increase with time and did not recur. Others showed, at some point postprostatectomy, rising PSA levels. The majority recurred. Therefore, this new ultrasensitive assay points to significant possible outcomes: (i) The ability to tell patients, who have undetectable PSA levels with conventional assays, but detectable and nonrising levels with the barcode assay, that their cancer will not recur. (ii) The ability to assign recurrence earlier because of the ability to measure increasing levels of PSA before conventional tools can make such assignments. (iii) The ability to use PSA levels that are not detectable with conventional assays to follow the response of patients to adjuvant or salvage therapies.

Evaluation of Gentian cystatin C reagent on Abbott Ci8200 and calculation of glomerular filtration rate expressed in mL/min/1.73 m2from the cystatin C values in mg/L

OBJECTIVE

Estimation of the glomerular filtration rate (GFR) is essential when evaluating patients with kidney disease and treating patients with drugs eliminated from the circulation by the kidneys. Cystatin C has been shown in several studies to be superior to creatinine in the estimation of GFR. At our hospitals, there is an increasing demand for cystatin C and at present we perform approximately 1500 cystatin C analyses a month. We thus need the assay available 24 h/day and to have it on our routine chemistry instrument to minimize handling time per test and time to reported test results.

MATERIAL AND METHODS

We have evaluated a new cystatin C immunoassay from Gentian (Gentian, Moss, Norway) on Architect ci8200 (Abbott Laboratories, Abbott Park, Ill., USA). A prerequisite at our hospital is that cystatin C results are reported as a calculated GFR in mL/min/1.73 m(2), so we also made a comparison with iohexol clearance.

RESULTS

The Gentian cystatin C assay showed good agreement with the corresponding assay from Dade Behring (Deerfield, Ill., USA) and good inter-laboratory concordance. The assay has very low total imprecision, good linearity and strong correlation with iohexol clearance (R (2) = 0.956). The equation for the correlation curve is: y = 79.901x(-1.4389).

CONCLUSIONS

There was low inter-laboratory variation between the three laboratories involved in the cystatin C evaluation, and thus all three laboratories can use the same equation for calculating the estimated GFR.

The fundamental flaws of immunoassays and potential solutions using tandem mass spectrometry

Immunoassays have made it possible to measure dozens of individual proteins and other analytes in human samples for help in establishing the diagnosis and prognosis of disease. In too many cases the results of those measurements are misleading and can lead to unnecessary treatment or missed opportunities for therapeutic interventions. These cases stem from problems inherent to immunoassays performed with human samples, which include a lack of concordance across platforms, autoantibodies, anti-reagent antibodies, and the high-dose hook effect. Tandem mass spectrometry may represent a detection method capable of alleviating many of the flaws inherent to immunoassays. We review our understanding of the problems associated with immunoassays on human specimens and describe methodologies using tandem mass spectrometry that could solve some of those problems. We also provide a critical discussion of the potential pitfalls of novel mass spectrometric approaches in the clinical laboratory.

The bioanalysis of trastuzumab in human serum using precipitate-enhanced ellipsometry

For the bioanalysis of therapeutic monoclonal antibodies in biological matrices, immunoassays--especially enzyme-linked immunosorbent assays (ELISAs)--are the most widely used techniques. Although ELISAs are very sensitive, the obtained sensitivity is not always sufficient. In this study, we have investigated the possibilities of performing a precipitate-enhanced immunoassay (PEIA) with ellipsometric detection for the bioanalysis of the therapeutic monoclonal antibody trastuzumab. Hydrophobic silicon slides were coated with anti-idiotype trastuzumab antibodies. Trastuzumab in serum samples could bind to this primary catcher, and biotinylated anti-idiotype antibodies were used for detection. After binding of streptavidin-poly-horseradish peroxidase (HRP), the precipitating substrate 3,3'-diaminobenzidine tetrahydrochloride (DAB) was added. Precipitation speed was analyzed using a novel prototype eight-cell ellipsometer, and calibration curves were obtained by plotting this speed versus the trastuzumab concentration. Results demonstrate that the PEIA is at least four times more sensitive than the same ELISA using the chromogenic substrate 3,5,3',5'-tetramethylbenzidine (TMB) instead of precipitating DAB. The calibration range of the assay is 11 to 700 pg/ml. Serum samples are diluted 10 times prior to incubation corresponding to 110 to 7000 pg/ml in undiluted serum. Validation results demonstrate that these low concentrations can be analyzed accurately and precisely. In addition, samples of a patient treated with trastuzumab were analyzed with both the PEIA and the ELISA. Results demonstrate excellent correlation (r=0.984) between the methods. Thus, when more sensitivity is required than in a conventional immunoassay, a PEIA with ellipsometric detection may be a useful alternative. The prototype ellipsometer is still in development, and from the data obtained in this study, improvements will be implemented.

New onset of heterophilic antibody interference in prostate-specific antigen measurement occurring during the period of post-prostatectomy prostate-specific antigen monitoring

Laboratories evaluated whether an interference was causing a false-positive PSA for the Immulite 2000 immunoassay after a time course of increasing prostate-specific antigen (PSA) in a post-prostatectomy patient led to salvage therapy, which had no effect on the elevated PSA. Serial dilutions of PSA for the patient sample (6.1 ng/mL; post-prostatectomy reference range: <0.1 ng/mL [undetectable]) were linear ( r > 0.99). However, the PSA measurement was reduced to 0.1 ng/mL after pretreatment of the sample with heterophilic antibody blocking reagent. PSA was undetectable (<0.1 ng/mL) when measured using two alternative immunoassays. These results were consistent with the presence of heterophilic antibody interference for the Immulite 2000 assay. In this case, heterophilic antibody interference with PSA measurement must have originated during the period of post-prostatectomy monitoring, and the apparent progressive increases in PSA may have been due solely to the progressive increase of this heterophilic antibody assay interference. In the absence of clinical correlation, positive PSA monitoring results should always be assessed for heterophilic antibody interference for at least one time point.

Antiaggregatory and proangiogenic effects of a novel recombinant human dual specificity anti-integrin antibody

BACKGROUND

beta(3)-Integrins are involved in platelet aggregation via alpha(IIb)beta(3) [glycoprotein (GP)IIb-GPIIIa], and in angiogenesis via endothelial alpha(V)beta(3). Cross-reactive ligands with antiaggregatory and proangiogenic effects, both desirable in peripheral vasculopathies, have not yet been described.

OBJECTIVES

In vitro and in vivo characterization of antiaggregatory and proangiogenic effects of two recombinant human Fab fragments, with emphasis on beta(3)-integrins.

METHODS

Recombinant Fab fragments were obtained by phage display technology. Specificity, affinity and IC(50) were determined by immunodot assays, enzyme-linked immunosorbent assay (ELISA), and Scatchard plot analysis, and by means of human umbilical vein endothelial cells (HUVECs). Functional analyses included ELISA for interaction with fibrinogen binding to GPIIb-GPIIIa, flow cytometry for measurement of activation parameters and competitive inhibition experiments, human platelet aggregometry, and proliferation, tube formation and the chorioallantoic membrane (CAM) assay for measurement of angiogenic effects.

RESULTS

We observed specific and high-affinity binding to an intact GPIIb-GPIIIa receptor complex of two human Fab autoantibody fragments, with no platelet activation. Dose-dependent fibrinogen binding to GPIIb-GPIIIa and platelet aggregation were completely inhibited. One Fab fragment was competitively inhibited by abciximab and its murine analog monoclonal antibody (mAb) 7E3, whereas the other Fab fragment bound to cultured HUVECs, suggesting cross-reactivity with alpha(V)beta(3), and also demonstrated proangiogenic effects in tube formation and CAM assays.

CONCLUSIONS

These Fab fragments are the first entirely human anti-GPIIb-GPIIIa Fab fragments with full antiaggregatory properties; furthermore, they do not activate platelets. The unique dual-specificity anti-beta(3)-integrin Fab fragment may represent a new tool for the study and management of peripheral arterial vasculopathies.

Falsely elevated thyroid-stimulating hormone (TSH) level due to macro-TSH

We encountered a 60-year-old woman with remarkably elevated thyroid-stimulating hormone (TSH) level as measured by electrochemiluminescent immunoassay (ECLIA), but with no specific symptoms, and with normal levels of free T3 and free T4. We performed the following investigations: polyethylene glycol (PEG) precipitation test, human antimouse IgG antibody (HAMA) interference test, and 3 additional TSH measurements by chemiluminescent immunoassay (CLIA). We then performed 2 gel filtration chromatography (GFC) procedures; one was at pH 7.2, and the other was at pH 3.0. Although the recovery of TSH shown by the PEG precipitation test was 4% which was extremely low, no HAMA interference was observed. Moreover, 3 CLIA instruments also showed various high values. The first GFC showed that the main peak of TSH immunoreactivity by ECLIA was located at a slightly larger molecular weight position than that of IgG. By the second GFC, the sample from the peak fraction of the first GFC showed that the TSH peak disappeared completely at the previous retention time but newly appeared at the same retention time as the TSH monomer. Protein G-Agarose gel removed the majority of the TSH complex. In conclusion, the majority of TSH in her serum was macro-TSH; TSH and anti- TSH IgG autoantibody complex. We should keep the possibility of macro-TSH in mind in cases with unexpectedly high TSH values, especially in autoimmune thyroidal disorders.

Traumatic brain injury biomarkers: from pipeline to diagnostic assay development

In recent years, the term proteomics is often mentioned together with biomarker discovery, as proteomic studies have the capability of identifying unique and unobvious protein biomarkers from tissues or biofluids derived from animal models or human clinical samples inflicted with various diseases. Proteomics has yielded hundreds of potential biomarker candidates. However, biomarker discovery is only the beginning of a long road for generating a validated, clinically relevant, and FDA-approved biomarker assay. Many technical, financial, legal, and regulatory hurdles have to be overcome before the components can be commercially produced (1, 2). This chapter outlines in a condensed version the steps to successfully develop clinically acceptable biomarkers, given the marker of choice withstands the rigor of developmental challenges along the road.

Evaluation of a new commercial enzyme immunoassay for the detection of IgM antibodies to West Nile virus using a ratio method to eliminate nonspecific reactivity

As West Nile virus (WNV) has become endemic in the United States, following the first reported cases in New York during the summer of 1999, the demand for specific serology has increased. Several IgM capture ELISA assays for the detection of WNV-specific IgM have been approved by the Food and Drug Administration for in vitro diagnostic testing, including kits from Focus Diagnostics and InBios International, Inc. The Focus Diagnostics IgM capture ELISA has a background subtraction protocol and the InBios IgM capture ELISA implements a ratio method to detect nonspecific reactivity due to rheumatoid factor, heterophile antibodies, and other interfering substances. We compared the InBios IgM capture ELISA with the Focus Diagnostics capture ELISA. Agreement, sensitivity, and specificity of the InBios IgM capture ELISA were 99, 98, and 100%, respectively. Samples that originally tested positive on the Focus Diagnostics IgM capture ELISA without the subtraction protocol and were then determined negative following the subtraction protocol agreed 100% with the InBios IgM capture ELISA. We conclude that a method to eliminate background reactivity is a necessary portion of any anti-WNV IgM assay in order to eliminate false-positive results.

Present and Future Biochemical Markers for Detection of Acute Coronary Syndrome

The use of biochemical markers in the diagnosis and management of patients with acute coronary syndrome has increased continually in recent decades. The development of highly sensitive and cardiac-specific troponin assays has changed the view on diagnosis of myocardial infarction and also extended the role of biochemical markers of necrosis into risk stratification and guidance for treatment. The consensus definition of myocardial infarction places increased emphasis on cardiac marker testing, with cardiac troponin replacing creatine kinase MB as the "gold standard" for diagnosis of myocardial infarction. Along with advances in the use of more cardiac-specific markers of myocardial necrosis, biochemical markers that are involved in the progression of atherosclerotic plaques to the vulnerable state or that signal the presence of vulnerable plaques have recently been identified. These markers have variable abilities to predict the risk of an individual for acute coronary syndrome. The aim of this review is to provide an overview of the well-established markers of myocardial necrosis, with a special focus on cardiac troponin I, together with a summary of some of the potential future markers of inflammation, plaque instability, and ischemia.

Good effect of IgY against Pseudomonas aeruginosa infections in cystic fibrosis patients

This is an extended open study of oral prophylactic treatment with egg yolk antibodies against Pseudomonas aeruginosa, Anti-Pseudomonas IgY, of 17 Swedish patients with cystic fibrosis. They have been on prophylactic IgY treatment for up to 12 years and altogether for 114 patient years. A group of 23 Danish CF patients served as control. There has been a total absence of adverse events. Only 29 cultures have been positive for P. aeruginosa (cultures after chronic colonization not included), that is, 2.3/100 treatment months compared to 7.0/100 months in the control group (P = 0.028). In the IgY treated group only one pair of siblings (2/17) has been chronically colonized with P. aeruginosa compared to seven patients (7/23) in the control group. Atypical mycobacteria, S. maltophilia, A. xylosoxidans, and A. fumigatus have appeared only sporadically. There have been no cultures positive for B. cepacia. There was no decrease in pulmonary functions (P = 0.730) within the IgY group. Body mass index values were normal or close to normal for all IgY treated patients. In conclusion, Anti-Pseudomonas IgY has great potential to prevent P. aeruginosa infections.