Shirley A. Robertson

Rapid, Sensitive, and Specific Lateral-Flow Immunochromatographic Device To Measure Anti-Anthrax Protective Antigen Immunoglobulin G in Serum and Whole Blood

ABSTRACT Evidence from animals suggests that anti-anthrax protective antigen (PA) immunoglobulin G (IgG) from vaccination with anthrax vaccine adsorbed (AVA) is protective against Bacillus anthracis infection. Measurement of anti-PA IgG in human sera can be performed using either enzyme-linked immunosorbent assay or fluorescent covalent microsphere immunoassay (ELISA) (R. E. Biagini, D. L. Sammons, J. P. Smith, B. A. MacKenzie, C. A. Striley, V. Semenova, E. Steward-Clark, K. Stamey, A. E. Freeman, C. P. Quinn, and J. E. Snawder, Clin. Diagn. Lab. Immunol. 11:50-55, 2004). Both these methods are laboratory based. We describe the development of a rapid lateral-flow immunochromatographic assay (LFIA) test kit for the measurement of anti-PA IgG in serum or whole-blood samples (30-μl samples) using colloidal gold nanoparticles as the detection reagent and an internal control. Using sera from 19 anthrax AVA vaccinees (anti-PA IgG range, 2.4 to 340 μg/ml) and 10 controls and PA-supplemented whole-blood samples, we demonstrated that the LFIA had a sensitivity of approximately 3 μg/ml anti-PA IgG in serum and ∼14 μg/ml anti-PA IgG in whole blood. Preabsorption of sera with PA yielded negative anti-PA LFIAs. The diagnostic sensitivity and specificity of the assay were 100% using ELISA-measured anti-PA IgG as the standard. This kit has utility in determining anti-PA antibody reactivity in the sera of individuals vaccinated with AVA or individuals with clinical anthrax.

Latex specific IgE: performance characteristics of the IMMULITE 2000 3gAllergy assay compared with skin testing

BACKGROUND In the absence of a US Food and Drug Administration (FDA)-cleared latex skin testing reagent, in vitro tests remain important for the diagnosis of latex allergy. OBJECTIVE To evaluate the performance characteristics of IMMULITE 2000 3gAllergy (Immulite), a third-generation, FDA-cleared, continuous random-access immunoanalyzer, for the quantification of latex specific IgE. METHODS Stored serum samples (N = 201) from patients classified as having positive or negative latex puncture skin test results were measured for latex specific IgE levels using Immulite, and these data were compared with historical results from 3 second-generation, FDA-cleared IgE antilatex assays (AlaSTAT [Ala], AutoCAP [CAP], and HY*TEC enzyme immunoassay [HT]). RESULTS The diagnostic performances of the CAP, Ala, and Immulite assays (> or = 0.35 kU/L cutoff value) were equivalent in sensitivity and specificity (P > .05). The HT assay (> or = 0.05 kU/L cutoff value) was more sensitive and less specific (P < .05). Immulite (> or = 0.10 kU/L cutoff value) had greater sensitivity than Ala and CAP and greater specificity than HT (P < .05 for both). Diagnostic efficiency was greater for Immulite than for CAP, Ala, and HT (P < .05). CONCLUSIONS The Immulite system is superior in diagnostic performance, especially at the 0.10 kU/L or greater cutoff level, for the diagnosis of latex allergy compared with older, second-generation assays. Immulite still misclassifies 15.5% of puncture skin test-positive individuals as negative for latex specific IgE. Compared with second-generation assays, Immulite represents a technological advance, with enhanced speed and less operator intervention.

A pilot respiratory health assessment of nail technicians: Symptoms, lung function, and airway inflammation †‡

BACKGROUND Recent surveys suggest nail technicians, particularly artificial nail applicators, have increased respiratory symptoms and asthma risk. METHODS We examined lung function (n = 62) and a marker of airway inflammation, i.e., exhaled nitric oxide (ENO) (n = 43), in a subset of nail technician and control participants in a pilot health assessment. RESULTS Bivariate analysis of technicians demonstrated that job latency was inversely correlated with FEV1 percent predicted (FEV1PP) (r = -0.34, P = 0.03) and FVCPP (r = -0.32, P = 0.05). Acrylic gel contact hours were inversely correlated with FEV1PP (r = -0.38, P = 0.02) and FVCPP (r = -0.47, P = 0.003). Current smoking was inversely and significantly (P <or= 0.05) associated with ENO in bivariate analysis. Log 10 ENO levels were directly correlated with job latency (P = 0.012) and gel nail application (P = 0.026) in multivariable analyses. CONCLUSIONS These positive pilot respiratory test results warrant additional future investigation.

Assessment of Exposure to PACs in Asphalt Workers: Measurement of Urinary PACs and their Metabolites with an ELISA Kit

An enzyme-linked immunosorbent assay (ELISA) kit made for determination of polycyclic aromatic compounds (PACs) in water was adapted for measuring PACs and their metabolites in urine. This method was then applied to a pilot asphalt worker PAC exposure study. Currently, liquid-liquid extraction with gas chromatography/isotope dilution high-resolution mass spectrometry (GC/HRMS) is the preferred method to determine urinary PAC metabolites. Although sensitive and specific, GC/HRMS is time consuming and costly. The ELISA method had a range from 14–720 ng/ml 1-hydroxypyrene equivalents with a lower limit of detection (LOD) of 14 ng/ml urine. ELISA and GC/HRMS PAC metabolite measurements had a statistically significant correlation and the PAC ELISA results were indicative of potential asphalt exposure. PAC ELISA is promising as a more rapid and less costly routine method for determining worker exposure to PACs in asphalt emissions.

Rapid Point-of-Care Test To Detect Broad Ranges of Protective Antigen-Specific Immunoglobulin G Concentrations in Recipients of the U.S.-Licensed Anthrax Vaccine

ABSTRACT Currently, there is no routine monitoring of an immune response to the anthrax vaccine. Simple on-site tests are needed to evaluate the antibody response of anthrax-vaccinated individuals in the Armed Forces and others at high risk. Using a prototype lateral flow assay (LFA) (R. E. Biagini, D. L. Sammons, J. P. Smith, B. A. MacKenzie, C. A. F. Striley, J. E. Snawder, S. A. Robertson, and C. P. Quinn, Clin. Vaccine Immunol. 13:541-546, 2006), we investigated the agreement between a validated anthrax protective antigen (PA) immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) and the LFA for 335 unvaccinated and vaccinated subjects. We also investigated the performance of the LFA under the following conditions: thermal shock (i.e., thermal cycling between temperature extremes), high temperature/high relative humidity, high temperature/low relative humidity, and low temperature/low relative humidity. With the anti-PA ELISA used as a standard, the LFA was shown to be optimally diagnostic at 11 μg/ml anti-PA-specific IgG. At this concentration, the LFA specificity and sensitivity were 98% (95% confidence interval [CI], 97% to 100%) and 92% (CI, 88% to 97%), respectively. Receiver operating characteristic curve analysis yielded an area under the curve value of 0.988 (CI, 0.976 to 1.00), suggesting that the LFA is an extremely accurate diagnostic test. For ≤4 or ≥50 μg/ml PA-specific IgG, the LFA results for each environmental condition were identical to those obtained in the laboratory. These data indicate that this rapid point-of-care test would be a feasible tool in monitoring the serological antibody responses of individuals that have been vaccinated against anthrax.

Use of Direct Reading Surface Sampling Methods for Site Characterization and Remediation of Methamphetamine Contaminated Properties

Residual methamphetamine contamination in Clandestine laboratories represents a hazard to emergency response personnel, remediation workers and the general public. To address this threat, two rapid, sensitive surface sampling techniques to assess the location and level of methamphetamine contamination were developed. Both methods employ established industrial hygiene surface sampling materials (wipes and swabs) but differ in their sensitivity and detection technology. One method, based on colorimetric disclosure, detects and confirms a collected sample or visible residues. The second method uses a lateral flow immunochemical assay (LFIA) for semi-quantitative detection of trace contamination. The National Institute for Occupational Safety and Health (NIOSH) partnered with public health agencies to develop applications of the methods for assessment of methamphetamine contamination of suspected properties. These applications focused on safe strategies for site assessment, hazard characterization, and remediation effectiveness. To conduct the field studies, NIOSH researchers and their partners visited more than a dozen suspected laboratories including mobile labs, abandoned properties, occupied residences, and motel rooms. NIOSH found greater than 95% agreement between positive identification of the presence of methamphetamine by LFIA and laboratory-based, liquid chromatography mass spectroscopy (LC–MS) methods. Test results were used to develop site assessments and make personal protective equipment recommendations. Results were also used to conduct process-based decontamination of properties and to make health-based decisions on remediation, re-occupancy of residences, as well as determine the degree of contamination of personal property in an inactive clandestine laboratory. By partnering with stakeholders, NIOSH was able to achieve two primary goals: (1) to develop a level of awareness in health department sanitarians, law enforcement personnel and other first responders that methamphetamine surface contamination was a potentially significant route of exposure; (2) to validate our methods in the field and to develop protocols for proper use and interpretation of the results.

Detection and measurement of surface contamination by multiple antineoplastic drugs using multiplex bead assay

Objectives Contamination of workplace surfaces by antineoplastic drugs presents an exposure risk for healthcare workers. Traditional instrumental methods to detect contamination such as liquid chromatography–mass spectrometry/mass spectrometry (LC–MS/MS) are sensitive and accurate but expensive. Since immunochemical methods may be cheaper and faster than instrumental methods, we wanted to explore their use for routine drug residue detection for preventing worker exposure. Methods In this study we examined the feasibility of using fluorescence covalent microbead immunosorbent assay (FCMIA) for simultaneous detection and semi-quantitative measurement of three antineoplastic drugs (5-fluorouracil, paclitaxel, and doxorubicin). The concentration ranges for the assay were 0–1000 ng/ml for 5-fluorouracil, 0–100 ng/ml for paclitaxel, and 0–2 ng/ml for doxorubicin. The surface sampling technique involved wiping a loaded surface with a swab wetted with wash buffer, extracting the swab in storage/blocking buffer, and measuring drugs in the extract using FCMIA. Results There was no significant cross-reactivity between these drugs at the ranges studied indicated by a lack of response in the assay to cross analytes. The limit of detection (LOD) for 5-fluorouracil on the surface studied was 0.93 ng/cm2 with a limit of quantitation (LOQ) of 2.8 ng/cm2, the LOD for paclitaxel was 0.57 ng/cm2 with an LOQ of 2.06 ng/cm2, and the LOD for doxorubicin was 0.0036 ng/cm2 with an LOQ of 0.013 ng/cm2. Conclusion The use of FCMIA with a simple sampling technique has potential for low cost simultaneous detection and semi-quantitative measurement of surface contamination from multiple antineoplastic drugs.

Evaluation of the prevalence of anti-wheat-, anti—flour dust-, and anti-alpha amylase-specific IgE antibodies in blood donors*

Background: Asthma in bakery workers is one of the most frequently occurring forms of occupational asthma in the world. Experience from other countries has shown the prevalence of sensitization (IgE) to bakery-associated allergens (BAAs) (wheat [W], flour dust [FD], -amylase [AA]) in bakery workers to be 5% to 53%, whereas the prevalence in nonoccupationally exposed individuals was estimated to be 1.2% to 6.4%. Objective: To estimate the prevalence of BAA sensitization by measuring BAA specific IgE in the residual serum tubes of volunteer blood donors. Methods: Serum samples from 534 volunteer blood donors were measured for anti-W, anti-FD, and anti-AA specific IgE antibodies (in duplicate) using the AlaSTAT microplate assay. Samples with BAA IgE concentrations of 0.35 kU/L or greater were considered positive. Results: Nineteen of 530 serum samples (3.6%; 95% confidence interval [CI], 3.3%–3.9%) were positive for W (range, 0.38–3.61 kU/L), whereas 31 of 534 (5.8%; 95% CI, 5.3%–6.3%) were positive for FD (range, 0.35–2.34 kU/L) and 5 of 529 (1.0%; 95% CI, 0.9%–1.1%) were positive for AA (range, 0.38–1.59 kU/L). Thirteen serum samples were positive for both W and FD; 1 sample each was positive for W and AA and FD and AA. Conclusions: The prevalence of IgE sensitization in serum samples from a relatively large unselected population of volunteer blood donors is 1.0% for AA, 3.6% for W, and 5.8% for FD, which agrees well with data from other countries for sensitization prevalence rates for nonoccupationally exposed individuals. Ann Allergy Asthma Immunol. 2004;92:649–653.