Limited Cross-reactivity Research Articles

Nonclinical development of biopharmaceuticals

The nonclinical development plan (NDP) for biotechnology-derived pharmaceuticals (biologics) as addressed in this review comprises aspects of nonclinical drug safety (toxicology and safety pharmacology), nonclinical pharmacokinetics (PKs) and nonclinical and clinical bioanalytics. A variety of bioanalytical methods are needed to describe PK behavior and to monitor immune response in laboratory animals and humans. The NDP will often differ from established programs for small molecules to account for target differences, a lack of or limited species crossreactivity and/or the limited applicability of long-term studies, as well as immunogenicity assessment. Special study designs, scientifically justified and driven by a case-by-case approach, might overcome these hurdles.

Validation and field testing of library-independent microbial source tracking methods in the Gulf of Mexico

Water quality is frequently impacted by microbial pollution from human and animal feces. Microbial source tracking (MST) can identify dominant pollution sources and improve assessment of health risk compared to indicator bacteria alone. This study aims to standardize and validate MST methods across laboratories in coastal Gulf of Mexico states. Three laboratories evaluated library-independent MST methods for human sewage detection via conventional PCR: (1) human-associated Bacteroidales, (2) human polyomaviruses (HPyVs), and (3) Methanobrevibacter smithii. All methods detected targets in human sewage seeded into buffer, freshwater or marine water (100% sensitivity). The limit of detection (LOD) for human sewage was lowest for the Bacteroidales assay (10 −5–10 −6 dilution). LODs for HPyVs and M. smithii assays were similar to each other (10 −3–10 −4), but were higher than Bacteroidales. The HPyVs assay was 100% specific, showing no cross-reactivity to dog, cow, cat, bird, or wild animal feces among >300 samples from three Gulf Coast regions. The human Bacteroidales assay was 96% specific, but cross-reacted with 10% of dog and some chicken samples. The M. smithii assay was 98% specific with limited cross-reactivity with cow, dog and seagull samples. An experts’ workshop concluded that all methods showed sufficient accuracy and reliability to move forward. SOPs will be distributed to collaborating laboratories for further inter-laboratory comparison, and field validation will occur in year 2.

Vaccination with survivin and PSMA-derived peptides for controlling biochemical recurrence in prostate cancer: A pilot study

e16042 Background: A significant percentage of patients (pts) progress after first line treatment of prostate cancer (PCa). We present preliminary results of pilot study using a multiple peptide-based anti-tumor vaccine. Methods: A phase I-II trial of vaccination (vax) with HLA-A*0201-restricted peptides from PSMA and Survivin was carried out in 20 pts with b-failure after surgery or radiotherapy (mean pre-vax PSA: 1.83 ng/ml). Vax consisted of two peptides from PSMA (PSMA4–12 and PSMA711–719) and one from Survivin (SVV96–104/97M) given by 4 fortnightly (priming) and 4 monthly administrations (boosting). To selectively eliminate regulatory T cells (Treg) and possibly enhance immunization, peptides were preceded by low dose cyclophosphamide (CTX, 300 mg/mq, i.v.). Antigen (Ag) and tumor-specific T cell responses were extensively monitored in peripheral blood together with CD4+CD25+Foxp3+ Treg frequency. PSA trend was also registered. Results: Vax was well tolerated. Most pts (19/20) showed a significant increase of SVV96–104/97M-specific T cells (mean 14 in pre-vax vs 170 in post-vax PBMC), while response to PSMA was achieved in about half of the pts and only to PSMA711–719 peptide (mean 12 in pre-vax vs 86 in post-vax PBMC). Increments of HLA-A*0201/SVV96–104/97M or PSMA711–719 multimer+ CD8+ T cells were induced in 50 and 35% pts, respectively. Vax-induced Ag-specific T cells displayed however limited cross-reactivity with HLA-A*0201+ PCa cells. No effect of CTX on Treg frequency was observed. 6 pts had no biochemical response to vax and switched to hormonal therapy, while 14/20 exhibited a significant although transient PSA decrease during vax (11 in the priming phase and 3 in boosting). Conclusions: Peptide vax could rapidly enhance Ag-specific immune responses in most treated pts. However, the reduced ability of vax-induced Ag-specific CD8+ T cells to cross-recognize PCa cells, together with their low frequency in PBMC, could explain why PSA control was achieved only transiently and in strict dependence with vax administration. Anti- tumor vax represent a useful tool for controlling PCa biochemical recurrence in the absence of major side effects, but immunization protocols inducing efficient tumor cell killing still need to be identified. No significant financial relationships to disclose.

Single-Chain Insulins as Receptor Agonists

Single chain insulins (SCIs) are single polypeptide chains in which the insulin B-chain links contiguously with the insulin A-chain via an uncleaved connecting peptide. While direct linkage of insulin Band A-chains produces SCIs with little insulin receptor binding, biologists have been interested in bioengineering linker peptides that form a flexible reverse turn, allowing SCIs to activate insulin receptors. In this report, we have investigated a series of cDNAs intended to explore the significance of linker length, cleavability, and the impact of certain site-dependent residues for the bioactivity of recombinant SCIs on insulin receptors. SCI concentration is readily measured by radioimmunoassay with a (proinsulin insulin)-specific polyclonal antibody. While dibasic flanking residues may result in potential endoproteolytic susceptibility, a linker with -Gln-Argflanking sequences resisted cleavage even in secretory granules, ensuring single-chain behavior. Effective SCIs exhibit favorable and specific binding with insulin receptors. SCIs with linkers bearing an Arg residue immediately preceding the A-chain were most bioactive, although efficient receptor interaction was inhibited as SCI linker length increased, approaching that observed for proinsulin. SCIs activate downstream metabolic signaling — stimulating glucose uptake into adipocytes and suppressing gluconeogenic enzyme biosynthesis in hepatocytes — with only limited cross-reactivity on IGF1 receptors. SCIs might theoretically have utility either in immunotherapy or gene therapy in insulin-deficient diabetes. The MOR-1 Opioid Receptor Regulates Glucose Homeostasis by Modulating Insulin Secretion Ting Wen, Bonnie Peng, and John E. Pintar (Mol Endocrinol, published February 12, 2009, 10.1210/me.2008-0345) ABSTRACT In addition to producing analgesia, opioids have also been proposed to regulate glucose homeostasis by altering insulin secretion. A considerable controversy exists, however, regarding the contribution of the opioid receptor (MOR-1) to insulin secretion dynamics. We employed congenic C57Bl/6J MOR-1 KO mice to clarify the role of MOR in glucose homeostasis. We first found that both sexes of MOR-1 KO mice weigh more than WT mice throughout postnatal life and that this increase includes preferentially increased fat deposition. We also found that MOR-1 KO mice exhibit enhanced glucose tolerance that results from insulin hypersecretion that reflects increased beta-cell mass and increased secretory dynamics in the MOR-1 mutant mice compared to WT. Analysis of the isolated islets indicated that islet insulin hypersecretion is mediated directly by MOR expressed on islet cells via a mechanism downstream of ATP-sensitive K channel activation by glucose. These findings indicate that MOR-1 regulates body weight by a mechanism that involves insulin secretion and thus may represent a novel target for new diabetes therapies. T R A N S L A T I O N A L H I G H L I G H T S F R O M M O L E C U L A R E N D O C R I N O L O G YIn addition to producing analgesia, opioids have also been proposed to regulate glucose homeostasis by altering insulin secretion. A considerable controversy exists, however, regarding the contribution of the opioid receptor (MOR-1) to insulin secretion dynamics. We employed congenic C57Bl/6J MOR-1 KO mice to clarify the role of MOR in glucose homeostasis. We first found that both sexes of MOR-1 KO mice weigh more than WT mice throughout postnatal life and that this increase includes preferentially increased fat deposition. We also found that MOR-1 KO mice exhibit enhanced glucose tolerance that results from insulin hypersecretion that reflects increased beta-cell mass and increased secretory dynamics in the MOR-1 mutant mice compared to WT. Analysis of the isolated islets indicated that islet insulin hypersecretion is mediated directly by MOR expressed on islet cells via a mechanism downstream of ATP-sensitive K channel activation by glucose. These findings indicate that MOR-1 regulates body weight by a mechanism that involves insulin secretion and thus may represent a novel target for new diabetes therapies. T R A N S L A T I O N A L H I G H L I G H T S F R O M M O L E C U L A R E N D O C R I N O L O G Y

Clonotypic density and cross-reactivity of the CD8+ memory T cell repertoire in adults. (83.12)

Abstract Adult memory T cell repertoires are populated by clonotypes that correspond to an individual's history of antigen exposures. The population density of clonotypes in the memory repertoire is important in light of the greatly reduced production of naïve T cells by the involuted thymus and the continuing need to respond to novel pathogens. We measure clonotypic density by comparing the recall response to the influenza-derived, HLA-A2 restricted, M158-66 peptide, with those to peptides substituted at positions 63 and 65 (TCR contact residues). The PBMC were from individuals who show a complex repertoire in recall response to the M158-66 peptide. All samples were obtained under an IRB approved protocol. Peptide-specific responses were identified by CDR3 spectratype analysis, and the clonotypes identified by sequencing the CDR3. As the substitutions became more pronounced, the M158-66 repertoire was lost and new responding clonotypes were revealed. However, the number of new clonotypes identified was lower than observed for M158-66. Structurally similar substitutions revealed a limited cross-reactivity in M158-66 repertoire. These data indicate that the adult repertoire is populated by T cells that can recognize structurally related epitopes. However, these T cells are sparsely distributed for the peptide:MHC structures generated by our substitutions.

Single-Chain Insulins as Receptor Agonists

Single-chain insulins (SCIs) are single polypeptide chains in which the insulin B-chain links contiguously with the insulin A-chain via an uncleaved connecting peptide. Although direct linkage of insulin B- and A-chains produces SCIs with little insulin receptor binding, biologists have been interested in bioengineering linker peptides that form a flexible reverse turn, allowing SCIs to activate insulin receptors. In this report, we have investigated a series of cDNAs intended to explore the significance of linker length, cleavability, and the impact of certain site-dependent residues for the bioactivity of recombinant SCIs on insulin receptors. SCI concentration is readily measured by RIA with a (proinsulin plus insulin)-specific polyclonal antibody. Although dibasic flanking residues may result in potential endoproteolytic susceptibility, a linker with -Gln-Arg- flanking sequences resisted cleavage even in secretory granules, ensuring single-chain behavior. Effective SCIs exhibit favorable and specific binding with insulin receptors. SCIs with linkers bearing an Arg residue immediately preceding the A-chain were most bioactive, although efficient receptor interaction was inhibited as SCI linker length increased, approaching that observed for proinsulin. SCIs activate downstream metabolic signaling, stimulating glucose uptake into adipocytes and suppressing gluconeogenic enzyme biosynthesis in hepatocytes, with only limited cross-reactivity on IGF-I receptors. SCIs might theoretically have utility either in immunotherapy or gene therapy in insulin-deficient diabetes.

Evaluation of Molecular Basis of Cross Reactivity between Rye and Bermuda Grass Pollen Allergens

Allergenic cross reactivity between the members of the Pooids (Lolium perenne, Phleum pratense, and Poa pratensis) and Chloridoids (Cynodon dactylon and Paspalum notatum) is well established. Studies using crude extracts in the past have demonstrated limited cross reactivity between the Pooids and the Chloridoids suggesting separate diagnosis and therapy. However, little is known regarding the molecular basis for the limited cross reactivity observed between the 2 groups of grasses. The present study was undertaken to gain insights into the molecular basis of cross allergenicity between the major allergens from rye and Bermuda grass pollens. Immunoblot inhibition tests were carried out to determine the specificity of the proteins involved in cross reactivity. Crude pollen extract and bacterially expressed and purified recombinant Lol p 1and Lol p 5 from rye grass were subjected to cross inhibition experiments with crude and purified recombinant Cyn d 1 from Bermuda grass using sera from patients allergic to rye grass pollen. The immunoblot inhibition studies revealed a high degree of cross inhibition between the group 1 allergens. In contrast, a complete lack of inhibition was observed between Bermuda grass group 1 allergen rCyn d 1, and rye grass group 5 allergen rLol p 5. Crude rye grass extract strongly inhibited IgE reactivity to Bermuda grass, whereas crude Bermuda grass pollen extract showed a weaker inhibition. Our data suggests that a possible explanation for the limited cross reactivity between the Pooids and Chloridoids may, in part, be due to the absence of group 5 allergen from Chloridoid grasses. This approach of using purified proteins may be applied to better characterize the cross allergenicity patterns between different grass pollen allergens.

Long-Term Nicotine Exposure Causes Increased Concentrations of Trypsinogens and Amylase in Pancreatic Extracts in the Rat

To develop radioimmunoassays (RIAs) for rat trypsinogens 1 and 2 and to investigate the effect of nicotine exposure on concentration and production of pancreatic zymogens in the rat. Male Sprague-Dawley rats were supplied with either normal or nicotine-containing (0.77 mM) water for 28 days and were then killed. Rabbit antibodies for the activation peptides of trypsinogens 1 and 2 were obtained for use in the RIAs. Concentrations of the both trypsinogens in pancreatic extracts were measured by the RIAs after activation by enterokinase. DNA and amylase were measured using commercial kits. mRNA for trypsinogens 1 and 2, procolipase, and cholecystokinin receptor was measured by in situ hybridization. The specificity of the RIA for the trypsinogen 1 activation peptide was satisfactory. The RIA for the trypsinogen 2 activation peptide showed a limited cross-reaction toward the synthetic trypsinogen 1 activation peptide, but the importance of this cross-reaction was moderate when investigated in samples of activated trypsinogens. Weight gain was reduced in nicotine-treated animals. Concentrations of amylase, trypsinogen 1, trypsinogen 2, and the ratio of trypsinogen 2 to 1 were all increased in pancreatic extracts of nicotine-fed animals. Total DNA and mRNA for the trypsinogens, procolipase, and cholecystokinin receptor were not affected by nicotine exposure. The combination of increased proenzyme concentrations and unaffected mRNA levels suggests that nicotine impairs secretion rather than production of pancreatic zymogens.

Allergenicity of Sigma and Delta Class Glutathione S-Transferases from the German Cockroach

Background: Cockroach glutathione S-transferases (GSTs) are known to elicit strong IgE responses. This study was undertaken to compare the IgE reactivity of German cockroach GSTs, Bla g 5 (σ class) and δ class GST (BgGSTD1). Methods: Full-length Bla g 5 and BgGSTD1 were cloned, and their recombinant proteins were expressed and purified. Their IgE reactivities and cross-reactivities were examined by ELISA using sera from cockroach-sensitized subjects. Results: A predominant variant of Bla g 5 cDNA has amino acid substitutions at positions 10 (C to F) and 42 (N to K). BgGSTD1 has substitutions at positions 27 (E to N) and 207 (K to R). Sera from cockroach-sensitized patients showed 20.5% IgE reactivity to Bla g 5 and 17.9% IgE reactivity to BgGSTD1. However, inhibition studies using 1 serum sample with the highest IgE reactivity showed limited cross-reactivity. Conclusions: IgE-binding frequency to the cockroach GSTs was low, but the titer of IgE reactivity was strong in some sera. The inclusion of different classes of GSTs could be helpful for the delicate diagnosis and immunotherapy of cockroach allergy.

Multiple antibody reactivities to citrullinated antigens in sera from patients with rheumatoid arthritis: association with HLA-DRB1 alleles

Background:Autoantibodies to cyclic citrullinated peptides (anti-CCP) are present in most patients with rheumatoid arthritis (RA), and associate with HLA-DRB1 shared epitope (SE) alleles.Objective:To investigate reactivities of anti-CCP to various citrullinated...

Cross‐Species Comparison of Metabolite Profiles in Chemosensory Epithelia: An Indication of Metabolite Roles in Chemosensory Cells

Comparative studies of chemosensory systems in vertebrates and invertebrates have greatly enhanced our understanding of anatomical and physiological constraints of chemical detection. Immunohistochemical comparisons of chemosensory systems are difficult to make across species due to limited cross-reactivity of mammalian-based antibodies. Immunostaining chemosensory tissues with glutaraldehyde-based antibodies generated against small metabolites in combination with hierarchical cluster analyses provide a novel approach for identifying and classifying cell types regardless of species. We used this "metabolite profiling" technique to determine whether metabolite profiles can be used to identify cell classes within and across different species including mouse, zebrafish, lobster and squid. Within a species, metabolite profiles for distinct cell classes were generally consistent. We found several metabolite-based cell classifications that mirrored function or receptor protein-based classifications. Although profiles of all six metabolites differed across species, we found that specific metabolites were associated with certain cell types. For example, elevated levels of glutathione were characteristic of nonsensory cells from vertebrates, suggesting an antioxidative role in non-neuronal cells in sensory tissues. Collectively, we found significantly different metabolite profiles for distinct cell populations in chemosensory tissue within all of the species studied. Based on their roles in other systems or cells, we discuss the roles of L-arginine, L-aspartate, L-glutamate, glycine, glutathione, and taurine within chemosensory epithelia.

Cross reactivity of enterohemorrhagic Escherichia coli O157:H7-specific sera with non-O157 serotypes

Escherichia coli O157:H7 is an important food- and water-borne pathogen of humans, causing Hemorrhagic Colitis and Haemolytic Uremic Syndrome. Colonization of both cattle and human hosts is mediated through the action of effector molecules secreted via a Type III secretion system, a mechanism shared by other enterohemorrhagic E. coli (EHEC). We recently reported that vaccination of cattle with Type III-secreted proteins (TTSPs) resulted in decreased shedding of the organism following both experimental infection as well as under conditions of natural exposure. In order to extend this to non-O157 EHEC serotypes, we examined the serological cross reactivity of TTSPs of serotypes O26:H11, O103:H2, O111:NM and O157:H7. Western blotting experiments with polyclonal antisera directed against serotype O157:H7 TTSPs suggested that there was significant cross reactivity, although there was limited cross reactivity when two Tir- and EspA-specific monoclonal antibodies were used. Groups of cattle were then vaccinated with TTSPs produced from each of the above serotypes and the magnitude and specificity of the responses were measured. All animals responded well with antibodies to TTSPs of the homologous serotype. However, limited cross reactivity was observed against the others. No cross reactivity was observed against Tir and EspA of serotype O157:H7. These results suggest that vaccination of cattle with TTSPs as a means of reducing the risk of EHEC transmission to humans will induce protection that is serotype specific.

A simple array platform for microRNA analysis and its application in mouse tissues

MicroRNAs (miRNAs) are a novel class of small noncoding RNAs that regulate gene expression at the post-transcriptional level and play a critical role in many important biological processes. Most miRNAs are conserved between humans and mice, which makes it possible to analyze their expressions with a set of selected array probes. Here, we report a simple array platform that can detect 553 nonredundant miRNAs encompassing the entire set of miRNAs for humans and mice. The platform features carefully selected and designed probes with optimized hybridization parameters. Potential cross-reaction between mature miRNAs and their precursors was investigated. The array platform was used to analyze miRNAs in the mouse central nervous system (CNS, spinal cord and brain), and two other non-CNS organs (liver and heart). Two types of miRNAs, differentially expressed organ/tissue-associated miRNAs and ubiquitously expressed miRNAs, were detected in the array analysis. In addition to the previously reported neuron-related miR-124a, liver-related miR-122a, and muscle-related miR-133a, we also detected new tissue-associated miRNAs (e.g., liver-associated miR-194). Interestingly, while the majority of pre-miRNAs were undetectable, miR690, miR709, and miR720 were clearly detected at both mature and precursor levels by the array analysis, indicating a limited cross-reaction between pre-miRNAs and their mature miRNAs. The reliability of this array technology was validated by comparing the results with independent Northern blot analyses and published data. A new approach of data normalization based on Northern blot analysis of one ubiquitously expressed miRNA is introduced and compared with traditional approaches. We expect this miRNA array platform to be useful for a wide variety of biological studies.

Identification of a novel virus in pigs—Bungowannah virus: A possible new species of pestivirus

In 2003 an outbreak of sudden deaths occurred in 3–4-week-old piglets on a farm in New South Wales, Australia. There was a marked increase in the birth of stillborn foetuses. Pathological changes consisted of a multifocal non-suppurative myocarditis. A viral infection was suspected but a wide range of known agents were excluded. A modified sequence independent single primer amplification (SISPA) method was used to identify a novel virus associated with this outbreak. Conserved 5′UTR motifs, the presence of a putative N pro coding region and limited antigenic cross-reactivity with other members of the Pestivirus genus, support the placement of this virus in the Pestivirus genus. Phylogenetic analysis of the 5′UTR, N pro and E2 coding regions showed this virus to be the most divergent pestivirus identified to date.

Limited IgE cross-reactivity between Dermatophagoides pteronyssinus and Glycyphagus domesticus in patients naturally exposed to both mite species

Contradictory results have been found when analyzing the IgE cross-reactivity among pyroglyphid mites and storage mites, as well as the role of these as true sensitizing agents. We sought to study the prevalence of sensitization to Glycyphagus domesticus in patients naturally exposed to this mite together with the more ubiquitous Dermatophagoides pteronyssinus and the IgE cross-reactivity between them. Mite species present in house dust samples of consecutive patients with mite allergy from Huelva (southwest Spain) were determined by means of light microscopy. Clinical sensitization was assessed by using skin prick and conjunctival provocation tests. Cross-reactivity at the IgE level was studied by using serum IgE determination and inhibition of RAST, IgE immunoblotting, and mite group 2 immunoassays. After D pteronyssinus, which is present in about 95% of house dust samples, G domesticus was the most important mite and present in about 50% of the samples. Tyrophagus putrescentiae and Lepidoglyphus destructor were detected in third and fourth place, respectively. About half of the patients with G domesticus at home were sensitized to this mite. A low IgE cross-reactivity was observed between D pteronyssinus and G domesticus, but an important IgE cross-reactivity was detected among glycyphagid mites at the level of group 2 allergens. Glycyphagid mites can act as primary sensitizing agents independently of pyroglyphid mites in a subset of patients naturally exposed to them. The inclusion of glycyphagid mite extracts in the diagnostic battery in areas with adequate mite growing conditions is important to ensure proper diagnosis.

Development of an Enzyme-Linked Immunosorbent Assay Method To Detect Mustard Protein in Mustard Seed Oil

An enzyme-linked immunosorbent assay for the detection of mustard protein was developed. The assay is based on a polyclonal antiserum directed against a mixture of mustard proteins raised in rabbits. The assay has a detection limit of 1.5 ppm (milligrams per kilogram) and is suitable for the detection of traces of mustard protein in mustard seed–derived flavoring ingredients. Limited cross-reactivity testing showed that no other plant proteins reacted significantly. From the animal proteins tested, only milk showed some cross-reactivity. With this sensitive assay, it was shown that refined mustard seed oil produced by steam distillation does not contain detectable amounts of mustard protein. Mustard seed oil is used as a flavoring in very low quantities, typically between 40 and 200 mg/kg. Thus, 100 g of a food product flavored with 200 mg of mustard seed oil per kg containing <1.5 mg of protein per kg would represent an amount of mustard seed protein of <30 ng. Taking into account the published literature on allergic reactions to the unintended ingestion of mustard, this conservatively low calculated level indicates that it is unlikely that food products containing mustard seed oil as a flavoring ingredient will elicit an allergic reaction in mustard-allergic individuals.

Rapid determination of Phytophthora infestans sporangia using a surface plasmon resonance immunosensor

Phytophthora infestans is the cause of late blight disease in potato and is an economically important pathogen worldwide. Early disease detection is important to implement disease control measures. In this study a surface plasmon resonance (SPR) immunosensor for detection of P. infestans sporangia is presented. The specificity of an existing mouse monoclonal antibody (phyt/G1470 mAb) against P. infestans was investigated in plate-trapped antigen ELISA and in subtractive inhibition ELISA. No or only limited cross-reactivity was observed against representatives having air-borne spores from Ascomycetes, Deuteromycetes as well as Basidiomycetes. phyt/G1470 mAb was incorporated in a subtractive inhibition SPR assay, consisting of a pre-incubation of mAb and sporangia, a centrifugation step to remove sporangia-bound phyt/G1470 mAb and quantification of remaining phyt/G1470 mAb by SPR. Good intra- and interday assay variability was observed and the assay had a detection limit of 2.2 × 10 6 sporangia/ml. Analysis time was 75 min, which is superior to existing P. infestans detection methods.

Evaluation of the Cepheid GeneXpertR system for detecting Bacillus anthracis

The Cepheid GeneXpert is a four-site, automated sample preparation and real-time PCR detection system. In this study, the capability of the GeneXpert to isolate and detect nucleic acid from Bacillus anthracis Ames spores was assessed. A four-plex, dried-down bead cartridge containing PCR reagents specific for the pXO1 and pXO2 plasmids as well as sample processing and inhibition controls was evaluated. For B. anthracis Ames spores harbouring pXO1 and pXO2, samples containing 68 CFU per ml (148 spores per ml) were positive in all four replicates. A limited cross-reactivity panel, which included closely related Bacillus species, was also tested to determine the specificity of the pXO1 and pXO2 assays. No cross-reactivity occurred. Further, B. anthracis Sterne spore samples were analysed to compare results when processed using the GeneXpert to those run directly on the Cepheid SmartCycler without sample processing. The GeneXpert detection capability was three logs lower than the SmartCycler indicating the benefit of incorporating a nucleic acid extraction procedure. This study demonstrates that the GeneXpert is a rapid and reliable system for simultaneously detecting the B. anthracis virulence plasmids pXO1 and pXO2. The GeneXpert is the only platform currently available that is capable of both nucleic acid purification and real-time PCR detection enclosed within a single system. Further, all sample manipulations are automated, thus reducing errors associated with manual processing.

Enzyme exposure in the British baking industry

Enzymes are commonly used in the baking industry, as they can improve dough quality and texture and lengthen the shelf life of the final product. There is little published information highlighting exposure to enzymes (other than fungal alpha-amylase) in the baking industry, therefore the purpose of this study was to identify antibodies and develop assays for the measurement of a variety of such enzymes in samples of airborne flour dust. Polyclonal antibodies to bacterial amylase, glucose oxidase and amyloglucosidase were identified and developed into ELISA assays. The assays showed limited cross-reactivity with other enzymes commonly used in the baking industry. We measured levels of airborne enzymes in 195 personal air samples taken from a sample of 55 craft baking establishments. We were able to detect amyloglucosidase in 9% (16/184) of the samples, fungal alpha-amylase in 6% (11/171), bacterial alpha-amylase in 7% (13/195). However, we were unable to detect glucose oxidase in any of the samples. Measurements for protease enzymes were not carried out. Median levels in detectable samples of amyloglucosidase, fungal alpha-amylase and bacterial amylase were similar at 10.3, 5.3 and 5.9 ng/m(3), respectively. These figures represent the total enzyme protein (active and inactive) measured. There are few data in the literature regarding sensitization and exposure-response relationships to these enzymes, and indeed there is often a lack of information within the industry as to the precise enzyme content of particular baking ingredients. As a precautionary measure, all enzymes are regarded as having the potential to cause respiratory sensitization. Consequently, exposures need to be controlled to as low a level as reasonably practicable, and future investigation may highlight the importance of measuring a variety of enzyme exposures and standardizing these methodologies to inform approaches to adequate control.

T cell‐mediated hypersensitivity to quinolones: mechanisms and cross‐reactivity

Quinolones are widely used, broad spectrum antibiotics that can induce immediate- and delayed-type hypersensitivity reactions, presumably either IgE or T cell mediated, in about 2-3% of treated patients. To better understand how T cells interact with quinolones, we analysed six patients with delayed hypersensitivity reactions to ciprofloxacin (CPFX), norfloxacin (NRFX) or moxifloxacin (MXFX). We confirmed the involvement of T cells in vivo by patch test and in vitro by means of the lymphocyte proliferation test (LTT). The nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones were investigated through the generation and analysis (flow cytometry and proliferation assays) of quinolone-specific T cell clones (TCC). The LTT confirmed the involvement of T cells because peripheral blood mononuclear cells (PBMC) mounted an enhanced in vitro proliferative response to CPFX and/or NRFX or MXFX in all patients. Patch tests were positive after 24 and 48 h in three out of the six patients. From two patients, CPFX- and MXFX-specific CD4(+)/CD8(+) T cell receptor (TCR) alphabeta(+) TCC were generated to investigate the nature of the drug-T cell interaction as well as the cross-reactivity with other quinolones. The use of eight different quinolones as antigens (Ag) revealed three patterns of cross-reactivity: clones exclusively reacting with the eliciting drug, clones with a limited cross-reactivity and clones showing a broad cross-reactivity. The TCC recognized quinolones directly without need of processing and without covalent association with the major histocompatability complex (MHC)-peptide complex, as glutaraldehyde-fixed Ag-presenting cells (APC) could present the drug and washing quinolone-pulsed APC removed the drug, abrogating the reactivity of quinolone-specific TCC. Our data show that T cells are involved in delayed immune reactions to quinolones and that cross-reactivity among the different quinolones is frequent.