Genetic variants within the MHC region are associated with immune responsiveness to childhood vaccinations.

The influence of genetic variability within the major histocompatibility complex (MHC) region on variations in immune responses to childhood vaccination was investigated. The study group consisted of 135 healthy infants who had been immunized with hepatitis B (HBV), 7-valent pneumococcal conjugate (PCV7), and diphtheria, tetanus, acellular pertussis (DTaP) vaccines according to standard childhood immunization schedules. Genotype analysis was performed on genomic DNA using Illumina Goldengate MHC panels (Mapping and Exon Centric). At the 1 year post vaccination check-up total, isotypic, and antigen-specific serum antibody levels were measured using multiplex immunoassays. A number of single nucleotide polymorphisms (SNPs) within MHC Class I and II genes were found to be associated with variations in the vaccine specific antibody responses and serum levels of immunoglobulins (IgG, IgM) and IgG isotypes (IgG1, IgG4) (all at p<0.001). Linkage disequilibrium patterns and functional annotations showed that significant SNPs were strongly correlated with other functional regulatory SNPs. These SNPs were found to regulate the expression of a group of genes involved in antigen processing and presentation including HLA-A, HLA-C, HLA-G, HLA-H, HLA-DRA, HLA-DRB1, HLA-DRB5, HLA-DQA1, HLA-DQB1, HLA-DOB, and TAP-2. The results suggest that genetic variations within particular MHC genes can influence immune response to common childhood vaccinations, which in turn may influence vaccine efficacy.

Thyroxine and free thyroxine levels in workers occupationally exposed to inorganic lead.

BACKGROUND: The effects of lead exposure on thyroid function are unclear. METHODS: Serum thyroxine (T4) was evaluated among 137 lead-exposed workers and 83 non-exposed workers. Free thyroxine (FT4) was evaluated among a subset of these workers. Exposure metrics included blood lead level (BLL), which reflects recent exposure, zinc protoporphyrin (ZPP), a marker of intermediate-duration lead exposure, exposure duration, and estimated cumulative exposure. Multiple linear regression results were adjusted for age, race, and current smoking status. RESULTS: Mean BLLs were 38.9 µg/dL in lead exposed workers and 2.1 µg/dL in non-exposed workers. The adjusted mean T4 and FT4 concentrations among exposed and non-exposed workers were similar. While T4 was not significantly related to any of the exposure metrics, FT4 was inversely related to the logged values of both exposure duration and cumulative exposure, but not to ZPP or BLL. CONCLUSIONS: The findings suggest that FT4 levels may be related to long-term lead exposure.

Exposure to flour dust and sensitization among bakery employees.

BACKGROUND: The National Institute for Occupational Safety and Health conducted a study to determine prevalences of sensitization to bakery-associated antigens (BAAs) and work-related respiratory symptoms at a large commercial bakery. METHODS: The following measurements were carried out: personal breathing zone (PBZ) and general area (GA) monitoring for inhalable flour dust, α-amylase and wheat, a questionnaire, and blood tests for IgE specific to flour dust, wheat, α-amylase, and common aeroallergens. RESULTS: Of 186 bakery employees present during our site visit, 161 completed the questionnaire and 96 allowed their blood to be drawn. The geometric mean PBZ and GA inhalable flour dust concentrations for the lower-exposure group was 0.235 mg/m(3), and for the higher-exposure group was 3.01 mg/m(3). Employees in the higher-exposure group had significantly higher prevalences of work-related wheezing, runny nose, stuffy nose, and frequent sneezing than the lower-exposure group. The prevalence of IgE specific to wheat was significantly higher among employees who ever had a job in the higher-exposure group or in production at another bakery at both the ≥ 0.10 kU/L and the ≥ 0.35 kU/L cutoffs, and to flour dust and α-amylase at the ≥ 0.10 kU/L cutoff, compared to the lower-exposure group. CONCLUSIONS: Despite knowledge of the risks of exposure to flour being available for centuries, U.S. employees are still at risk of sensitization and respiratory symptoms from exposure to high levels of BAA.

Interlaboratory comparison of three multiplexed bead-based immunoassays for measuring serum antibodies to pneumococcal polysaccharides.

Serotype-specific IgG, as quantified by a standardized WHO enzyme-linked immunosorbent assay (ELISA), is a serologic end point used to evaluate pneumococcal polysaccharide-based vaccine immunogenicity. Antibodies to each vaccine polysaccharide in licensed multivalent vaccines are quantified separately; this is laborious and consumes serum. We compared three bead-based immunoassays: a commercial assay (xMAP Pneumo14; Luminex) and two in-house assays (of the Health Protection Agency [HPA] and Centers for Disease Control and Prevention [CDC]), using the WHO-recommended standard reference and reference sera (n = 11) from vaccinated adults. Multiple comparisons of the IgG concentrations for seven conjugate vaccine serotypes were performed by sample (percent error), serotype (equivalency testing), and laboratory (concordance correlation coefficient [CCC]). When comparing concentrations by sample, bead-based immunoassays generally yielded higher antibody concentrations than the ELISA and had higher variability for serotypes 6B, 18C, and 23F. None of the three assays met the current WHO recommendation of 75% of sera falling within 40% of the assigned antibody concentrations for all seven serotypes. When compared by serotype, the CDC and HPA tests were equivalent for five of seven serotypes, whereas the Luminex assay was equivalent for four of seven serotypes. When overall mean IgG concentrations were compared by laboratory, a higher level of agreement (CCC close to 1) was found among bead-based immunoassays than between the assays and WHO assignments. When compared to WHO assignments, the HPA assay outperformed the other assays (r = 0.920; CCC = 0.894; coefficient of accuracy = 0.972). Additional testing with sera from immunogenicity studies should demonstrate the applicability of this methodology for vaccine evaluation.

Influence of cytokine gene variations on immunization to childhood vaccines.

The magnitude of the immune response to vaccinations can be influenced by genetic variability. In the present study, we aimed to investigate whether cytokine or cytokine receptor gene polymorphisms were associated with variations in the immune response to childhood vaccination. The study group consisted of 141 healthy infants who had been immunized with hepatitis B vaccine (HBV), 7-valent pneumococcal conjugate (PCV7), and diphtheria, tetanus, acellular pertussis (DTaP) vaccines according to standard childhood immunization schedules. Genotype analysis was performed on genomic DNA using a 5' nuclease PCR assay. Post vaccination total, isotypic, and antigen-specific serum antibody levels were measured using multiplex immunoassays. Significant associations were observed between SNPs in the TNFalpha, IL-12B, IL-4Ralpha, and IL-10 genes and vaccine-specific immune responses (p<0.05). In addition, SNPs in the IL-1beta, TNFalpha, IL-2, IL-4, IL-10, IL-4Ralpha, and IL-12B genes were associated with variations in serum levels of immunoglobulins (IgG, IgA, IgM) and IgG isotypes (IgG1-IgG3) (p<0.05). These data suggest that genetic variations in cytokine genes can influence vaccine-induced immune responses in infants, which in turn may influence vaccine efficacy.

The anthrax vaccine: no new tricks for an old dog.

The original license for production of the anthrax vaccine, Anthrax Vaccine Adsorbed (AVA), was issued in 1970. Since that time, over 8 million AVA immunizations have been administered to 2+ million individuals. In 2002, the National Academy of Sciences, Institute of Medicine, reviewed the safety and efficacy of AVA. They concluded that the vaccine is acceptably safe and effective in protecting humans against anthrax. The vaccine should protect people against all known strains of anthrax bacteria, as well as against any strains that might be created by potential terrorists or others. Although the Institute of Medicine concluded that AVA was reasonably safe, they noted that it is fairly common for people to experience local reactions (e.g., redness and swelling at the injection site) and for a smaller number to experience systemic reactions such as fever and malaise, within hours or days of vaccination. Results of animal studies done previously and subsequent to this report are generally in agreement. For instance, AVA vaccination increases the level of anthrax anti-protective antigen IgG (anti-PA IgG), which is thought to be one possible correlate of protection (although absolute protective concentrations have not been identified in humans). Anthrax lethal factor neutralization has also been identified as possibly being an important additional correlate of immunity. Future vaccine research efforts include developing a recombinant anthrax vaccine and anthrax monoclonal antibodies to block the anthrax toxin(s). It is projected that the next-generation vaccine will elicit a markedly increased anti-anthrax immune response within a shorter time period and consequently, will enable the easier inoculations of individuals working within high-risk areas.

Evaluation of body mass index, pre-vaccination serum progesterone levels and anti-anthrax protective antigen immunoglobulin G on injection site adverse events following anthrax vaccination in women.

BACKGROUND: In 2002, CDC initiated the Anthrax Vaccination Program (AVP) to provide voluntary pre-exposure anthrax vaccination for individuals at high risk for exposure to Bacillus anthracis spores. The AVP offered an opportunity to investigate hypothesized reasons for a reported gender difference in injection site adverse events (AEs) following anthrax vaccine adsorbed (AVA). OBJECTIVES: To evaluate in women the impact of body mass index (BMI), pre-vaccination serum progesterone levels, and pre-vaccination anti-anthrax protective antigen immunoglobulin G concentrations (anti-PA IgG) on the occurrence of AEs following subcutaneous AVA vaccination. METHODS: Participants' BMI was determined at enrollment. Also, pre-vaccination blood samples were assayed for serum progesterone and anti-PA IgG. Post-vaccination solicited AEs were recorded by participants using a 4-day diary card. RESULTS: Obese group had an elevated risk for arm soreness. Decreased pre-vaccination serum progesterone level was associated with arm swelling. Increased pre-vaccination anti-PA IgG was associated with itching on the arm; and within the obese group, was associated with arm swelling, lump or knot, redness, soreness, and warmth. CONCLUSIONS: In AVA vaccinated women, obesity was associated with arm soreness and decreased pre-vaccination serum progesterone levels were associated with increased rate of arm swelling. Increased pre-vaccination anti-PA IgG may be associated with an increased frequency of itching on the arm, and in obese women, may increase the occurrence of arm swelling, lump or knot, redness, and warmth. Administering AVA according to a woman's menstrual phase may reduce the occurrence of certain injection site reactions.

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.

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 microg/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 < or = 4 or > or = 50 microg/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.

Analytical performance of the AtheNA MultiLyte ANA II assay in sera from lupus patients with multiple positive ANAs.

The purpose of this study was to evaluate the precision and accuracy of a commercial multiplexed kit for the measurement of 9 anti-nuclear antibodies (ANAs; anti-SS/A, anti-SS/B, anti-Sm, anti-RNP, anti-Jo-1, anti-Scl-70, anti-dsDNA, anti-Centromere B, and anti-Histone), and to compare these results to a subset of ANAs measured by enzyme-linked immunosorbent assays (ELISA) and immunodiffusion (ID). Sera were obtained from 22 systemic lupus erythematosus (SLE) patients, twelve controls and five others (commercial source) with various autoimmune diseases. ANA results from the AtheNA MultiLyte ANA II Assay (AtheNA) were compared to ELISA results (controls) and patients (ID). The AtheNA interassay coefficients of variation (CVs, N = 39, performed in duplicate; replicated 3x) ranged from 6.2% to 16.7% (mean = 9.8%), while the intra-assay CVs ranged from 5.8% to 14.3% (mean = 10.8%). Compared to results for SLE cases and controls, the sensitivity of AtheNA ranged from 85.7% to 100% (mean = 97.1%), while diagnostic specificity ranged from 16.7% to 100% (mean = 71.6%). There was significant agreement (P values ranging from 0.0001 to 0.03) when analytes coanalyzed by AtheNA and ELISA/ID were evaluated using Cohen's kappa (kappa values ranging from 0.376 to 1.000). No false positive ANA results were observed for either the control or commercial source autoimmune disease sera. These results indicate that the AtheNA assay is a precise and accurate alternative for performing multiple ELISAs or IDs in the diagnosis of autoimmune diseases, especially when the number of sera to be tested is large, such as in clinical screening or epidemiologic studies. It also appears that the AtheNA assay identifies positive ANA specificities which are missed by ID techniques, suggesting that it may have greater analytical sensitivity for some ANAs.

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.

Rapid, sensitive, and specific lateral-flow immunochromatographic device to measure anti-anthrax protective antigen immunoglobulin g in serum and whole blood.

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-microl 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 microg/ml) and 10 controls and PA-supplemented whole-blood samples, we demonstrated that the LFIA had a sensitivity of approximately 3 microg/ml anti-PA IgG in serum and approximately 14 microg/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.

Evaluation of the prevalence of antiwheat-, anti-flour dust, and anti-alpha-amylase specific IgE antibodies in US 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], alpha-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.

Clinical use of immunoassays in assessing exposure to fungi and potential health effects related to fungal exposure.

OBJECTIVE: To review and summarize current evidence regarding the proper role of immunoassays in clinical assessments of exposure to fungi and health effects related to fungal exposure. DATA SOURCES: We reviewed relevant scientific investigations and previously published reviews concerning this topic. STUDY SELECTION: The authors' clinical, laboratory, and public health experiences were used to evaluate relevant data for scientific merit. RESULTS: Testing to determine the presence of IgE to specific fungi may be a useful component of a complete clinical evaluation in the diagnosis of illnesses that can be caused by immediate hypersensitivity such as allergic rhinitis and asthma. Detection of IgG to specific fungi has been used as a marker of exposure to agents that may cause illnesses such as hypersensitivity pneumonitis. However, the ubiquitous nature of many fungi and the lack of specificity of fungal antigens limit the usefulness of these types of tests in the evaluation of potential building-related illness and fungal exposure. Specific serologic tests (such as tests for cryptococcal antigen, coccidioidal antibody, and Histoplasma antigen) have been shown to be useful in the diagnosis of some fungal infections, but these are the exception not the rule. CONCLUSIONS: There is currently not enough scientific evidence to support the routine clinical use of immunoassays as a primary means of assessing environmental fungal exposure or health effects related to fungal exposure. Health care providers who care for persons expressing concerns about the relationship of symptoms to potential exposure to fungi are advised to use immunoassay results with care and only as an adjunct to a comprehensive approach to patient care.

Comparison of a multiplexed fluorescent covalent microsphere immunoassay and an enzyme-linked immunosorbent assay for measurement of human immunoglobulin G antibodies to anthrax toxins.

Recently, the Centers for Disease Control and Prevention reported an accurate, sensitive, specific, reproducible, and quantitative enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) antibodies to Bacillus anthracis protective antigen (PA) in human serum (C. P. Quinn, V. A. Semenova, C. M. Elie et al., Emerg. Infect. Dis. 8:1103-1110, 2002). The ELISA had a minimum detectable concentration (MDC) of 0.06 microgram/ml, which, when dilution adjusted, yielded a whole-serum MDC of 3.0 micro g of anti-PA IgG per ml. The reliable detection limit (RDL) was 0.09 microgram/ml, while the dynamic range was 0.06 to 1.7 microgram/ml. The diagnostic sensitivity of the assay was 97.6% and the diagnostic specificity was 94.2% for clinically verified cases of anthrax. A competitive inhibition anti-PA IgG ELISA was also developed to enhance the diagnostic specificity to 100%. We report a newly developed fluorescence covalent microbead immunosorbent assay (FCMIA) for B. anthracis PA which was Luminex xMap technology. The FCMIA MDC was 0.006 microgram of anti-PA IgG per ml, the RDL was 0.016 microgram/ml, and the whole-serum equivalent MDC was 1.5 micrograms/ml. The dynamic range was 0.006 to 6.8 microgram/ml. Using this system, we analyzed 20 serum samples for anti-PA IgG and compared our results to those measured by ELISA in a double-masked analysis. The two methods had a high positive correlation (r2 = 0.852; P < 0.001). The FCMIA appears to have benefits over the ELISA for the measurement of anti-PA IgG, including greater sensitivity and speed, enhanced dynamic range and reagent stability, the use of smaller sample volumes, and the ability to be multiplexed (measurement of more than one analyte simultaneously), as evidenced by the multiplexed measurement in the present report of anti-PA and anti-lethal factor IgG in serum from a confirmed clinical anthrax infection.

Method for simultaneous measurement of antibodies to 23 pneumococcal capsular polysaccharides.

We describe a fluorescent covalent microsphere immunoassay (FCMIA) method for the simultaneous (multiplexed) measurement of immunoglobulin G (IgG) antibodies to 23 pneumococcal capsular polysaccharide (PnPS) serotypes present in the pneumococcal polysaccharide vaccine (PPV23) licensed by the Food and Drug Administration, i.e., PnPSs 1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F. In addition, the assay incorporates an internal control that allows for contemporaneous evaluation of the effectiveness of pneumococcal cell wall polysaccharide (C-PS) preadsorption and a second control of PnPS 25 (which is not present in any polysaccharide or conjugate vaccine), which can be used to evaluate interassay reproducibility (useful for pre- versus postvaccination studies). The FCMIA was standardized with U.S. reference antipneumococcal serotype standard serum 89S-2. Preadsorption of 89S-2 with each PnPS and C-PS yielded homologous inhibition for serotypes 1, 6B, 9N, 9V, 11A, 12F,14, 15B, 18C, 19A, 19F, 20, 22F, 25, and 33F; heterologous inhibition for serotypes 9V, 10A, 11A, 12F, 15B, 17F, 20, and 23F; and neither homologous nor heterologous inhibition for serotypes 2, 3, 4, and 5. The minimum detectable concentrations for the 24 multiplexed (PnPS and C-PS) FCMIAs ranged from 20 pg/ml for PnPS 3 to 600 pg/ml for PnPS 14. The PnPS FCMIA method has numerous benefits over enzyme-linked immunosorbent assays commonly used to measure anti-PnPS-specific IgG levels, including increased speed, smaller sample volumes, equivalent or better sensitivity, and increased dynamic range.

Biological monitoring for selected herbicide biomarkers in the urine of exposed custom applicators: application of mixed-effect models.

Metabolites and/or parent compounds of the herbicides atrazine, alachlor, metolachlor, cyanazine and the 2-ethylhexyl ester of 2,4-dichlorophenoxyacetic acid (2,4-D) were measured in the urine of 15 custom applicators who each provided from five to seven 24 h urine samples during a 6 week period (n = 87). Each applicator provided a pre-season urine sample and a reference population (n = 46) provided first-morning urine samples. Urinary biomarkers were measured by either immunoassay or gas chromatography. During the spraying season, the geometric mean amount of alachlor mercapturate equivalents (eq.), atrazine eq., 2,4-D and metolachlor mercapturate eq. excreted in 24 h was 17, 19, 110 and 22 nmol, respectively. Mixed-effect models were used to determine predictors of the amount of atrazine eq. and 2,4-D excreted in 24 h. The specific days of herbicide spraying associated with increased biomarker excretion varied for the two analytes, and included one or more days prior to urine collection. This confirms the importance of collecting covariate information on day(s) most relevant to the biomarker of interest. The within-worker variance component, expressed as a geometric standard deviation ((W)GSD range: 2.5-2.9), was substantially larger than the between-worker component ((B)GSD range: 1.3-1.5) for the modeled biomarkers. Alachlor mercapturate eq. and metolachlor mercapturate eq. were detected in more than half of the applicator pre-season urine samples. All biomarkers were detected infrequently in the reference population. Evaluation of non-spray exposure determinants was limited by inclusion of prior day spraying, adjustment for time and the small sample size.

In vivo sensitization to purified Hevea brasiliensis proteins in health care workers sensitized to natural rubber latex.

BACKGROUND: Thirteen proteins of natural rubber latex (Hevea brasiliensis) known to bind human IgE have been isolated and characterized as Hev b allergens. However, the in vivo importance of native Hev b allergens has not been defined in health care workers (HCWs) with natural rubber latex (NRL) allergy. OBJECTIVES: The principal aim of this study was to identify the major in vivo Hev b allergens in HCWs with NRL allergy confirmed by percutaneous sensitivity to nonammoniated latex (NAL). METHODS: Skin prick testing was performed with 7 (native) proteins purified from NAL (Hev b 1, 2, 3, 4, 6.01, 7.01, and a newly described Hev b 13) and recombinant Hev b 5 in 62 HCWs with histories of NRL allergy (group 1) confirmed by percutaneous reactivity to NAL and in 49 atopic HCWs without NRL allergy (group 2). Serial 10-fold concentrations of Hev b proteins (5 x 10(-5) microg/mL to 50 microg/mL) were tested; serum samples of subjects were assayed for serum specific IgE by immunoassays. RESULTS: Hev b 2, Hev b 5, Hev b 6.01, and Hev b 13 produced skin reactions in more than 60% of group 1 subjects, with Hev b 1, 3, 4, and 7.01 eliciting reactions in less than 50%. Only 1 of 49 group 2 workers reacted to a single Hev b antigen (Hev b 13). Specificity of 7 Hev b allergens was 100% and 98% for Hev b 13 in identifying workers with confirmed NRL allergy. Specific IgE by AlaSTAT and CAP immunoassays was elevated in 40 of 60 (67%) and 33 of 62 (53%) of NAL-reactive workers and produced false-positive test results in 4 of 49 (8%) and 3 of 48 (6%) group 2 subjects, respectively. CONCLUSION: Hev b 2, 5, and 6.01 are major in vivo allergens and Hev b 13 is a new major in vivo allergen among HCWs with allergy to NRL.