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Lars K Poulsen

Publications and source records attributed to Lars K Poulsen.

At least 19 recordsLinked to original sources
PubMed2007

Incomplete digestion of codfish represents a risk factor for anaphylaxis in patients with allergy.

BACKGROUND: Fish represents one of the most important allergenic foods causing severe allergic reactions. Nevertheless, it has been shown that gastric digestion significantly reduces its allergenic capacity. OBJECTIVE: In this study, we assessed the absorption kinetics of fish proteins and investigated the clinical reactivity of patients with fish allergy to codfish digested at physiological or elevated gastric pH. METHODS: Healthy individuals were openly challenged with codfish and blood samples were evaluated by histamine release for absorbed fish allergens. Patients with allergy were recruited on the basis of previously diagnosed codfish allergy. Fish extracts were digested with gastric enzymes at pH 2.0 and 3.0 and used for histamine release, skin prick tests, and titrated double-blind placebo-controlled food challenges. RESULTS: Ingestion experiments in subjects without allergy revealed absorption of biologically active fish allergens only 10 minutes after ingestion with maximal serum levels after 1 to 2 hours. Incubation of fish proteins with digestive enzymes at pH 2.0 resulted in a fragmentation of the proteins leading to a reduced biological activity evidenced by a significantly smaller wheal reaction and reduced histamine release. Fish digested at pH 3.0 revealed comparable reactivity patterns as undigested extracts. Moreover, these test materials triggered reactions at 10-fold to 30-fold lower cumulated challenge doses in patients with allergy. CONCLUSION: Our data indicate the paramount importance of gastric digestion for fish allergens because the quantitatively significant absorption and elicitation of symptoms seemed to take place in the intestine. CLINICAL IMPLICATIONS: Hindered digestion puts patients with fish allergy at risk to develop severe allergic reactions at minute amounts of allergens.

Adult↗
PubMed2007

Association between alcohol consumption and skin prick test reactivity to aeroallergens.

BACKGROUND: A few studies have indicated a positive association between consumption of alcohol and allergic sensitization in age and socioeconomically heterogeneous populations. OBJECTIVE: To investigate the association between consumption of alcohol and allergic sensitization in a young homogenous population of high social class (a group with a suspected high prevalence of sensitization). METHODS: A total of 1,668 students aged 18 to 35 years recruited from universities in Copenhagen, Denmark, underwent skin prick testing (SPT) in October or November 2002 and completed a questionnaire about respiratory disease and lifestyle habits, including alcohol consumption. SPT positivity was defined as a positive reaction (> or =3 mm) against at least 1 of 10 common inhalant allergens. RESULTS: Before and after adjustment for sex, age, smoking, atopic predisposition, and pet keeping, no significant association was found between alcohol consumption (including type of beverage) and SPT positivity. Increasing alcohol consumption was significantly negatively associated with asthma symptoms and hay fever symptoms. CONCLUSIONS: Alcohol consumption does not favor SPT positivity, but cumulated effects were not addressed in the present study. Individuals with asthma or hay fever symptoms seem to reduce alcohol intake (a healthy drinkers' effect).

Adolescent↗
PubMed2006

Diagnostic tests based on human basophils: potentials, pitfalls and perspectives.

Human basophils are important tools for studying immediate-type hypersensitivity reactions since they release a variety of mediators (e.g., histamine, leukotriene C4, IL-4 and IL-13) following allergen triggering. Several diagnostic tools have been introduced that measure either leukotriene production or the upregulation of surface markers (CD63 and CD203c) from these cells after antigen stimulation. However, a broad variability in basophil activity exists between different basophil donors and different antigens within one donor. This manifests itself in terms of their reactivity (maximum secretory response), based on the intracellular signaling of the basophils studied, and in terms of their sensitivity. The latter is governed by the number of IgE receptors per basophil, the ratio of antigen-specific IgE to total IgE, and by the number of cell surface antigen-specific IgE molecules for half-maximal responses, termed 'intrinsic sensitivity'. These variables give rise to shifts in the dose-response curves which, in a diagnostic setting where only a single antigen concentration is employed, may produce false-negative data. Thus, in order to meaningfully utilize the current basophil activation tests for diagnostic purposes, each allergen should be pre-evaluated separately in order to determine a suitable stimulation range. Additionally, anti-IgE or anti-FcepsilonRIalpha antibodies should serve as positive controls, bearing in mind that 10-20% of basophil donors are not responsive to IgE-mediated stimulation. Diagnostic studies using CD63 or CD203c in hymenoptera, food and drug allergy are critically discussed. Basophil-based tests are indicated for allergy testing in selected cases but should only be performed by experienced laboratories.

Animals↗
PubMed2006

CCR3, CCR5, CCR8 and CXCR3 expression in memory T helper cells from allergic rhinitis patients, asymptomatically sensitized and healthy individuals.

BACKGROUND: Chemokine receptors have been suggested to be preferentially expressed on CD4+ T cells with CCR3 and CCR8 linked to the T helper (Th) 2 subset and CCR5 and CXCR3 to the Th1 subset, however this remains controversial. OBJECTIVE: Our aim was to compare the CCR3, CCR5, CCR8 and CXCR3 expression in memory Th cells from allergic, asymptomatically sensitized and healthy individuals. METHODS: Peripheral blood mononuclear cells from 8 pollen allergic rhinitis patients, 10 asymptomatically sensitized and 10 healthy individuals were stimulated for 7 days with allergen or tetanus toxoid. CCR3, CCR5, CCR8, CXCR3, CD4 and CD45RO were detected by flow cytometry. RESULTS: No differences in chemokine receptor expression were observed between the three groups on day 0, and seven days of unstimulated culture did not change the expression. Both antigenic stimuli increased the chemokine receptor expression, tetanus toxoid being the most potent. No differences in percentage chemokine receptor positive memory Th cells were observed between the three groups on day 7. Only a change in MFI for CCR5 was significantly different between the three groups after allergen stimulation of the Th cells. CONCLUSION: We conclude that even though allergen and antigen induced increased chemokine receptor expression, no differences in profiles were identified in memory Th cells from patient groups with different atopic status.

Journal Article↗
PubMed2006

Signaling transduction pathways involved in basophil adhesion and histamine release.

BACKGROUND: Little is known about basophil with respect to the different signaling transduction pathways involved in spontaneous, cytokine or anti-IgE induced adhesion and how this compares to IgE-dependent and IgE-independent mediator secretion. The purpose of the present study was to investigate the roles of beta1 and beta2 integrins in basophil adhesion as well as hosphatidylinositol 3-kinase (PI3K), src-kinases and extracellular signal regulated kinase (ERK) 1/2 in basophil adhesion and histamine release (HR). METHODS: Basophils (purity of 10% - 50%) were preincubated with anti-CD29 or anti-CD18 blocking antibodies before used for adhesion study. Basophils were preincubated with the pharmacological inhibitors wortmannin, PP1, PD98059 before used for adhesion and HR study. Cell adherence to bovine serum albumin (BSA) or fibronectin (Fn) was monitored using cell associated histamine as a basophil marker and the histamine was measured by the glass fiber assay. RESULTS: Basophil spontaneous adhesion to Fn was inhibited by anti-CD29. Interleukin (IL)-3, granulocyte/macrophage colony stimulating factor (GM-CSF) induced adhesion to BSA was inhibited by anti-CD18. Wortmannin at 1 micromol/L and PP1 at 20 micromol/L strongly interfered with, whereas PD98059 at 50 micromol/L weakly inhibited basophil spontaneous adhesion to Fn. One micromol/L wortmannin strongly inhibited IL-3, IL-5, GM-CSF and anti-IgE induced adhesion to BSA. PP1 at 20 micromol/L partly inhibited anti-IgE induced adhesion. Fifty micromol/L PD98059 marginally inhibited IL-5, weakly inhibited anti-IgE, partly inhibited GM-CSF induced adhesion. Wortmannin, PP1 and PD98059 inhibited anti-IgE (1:100 or 1:1000) induced basophil HR in a dose dependent manner. They inhibited calcium ionophore A23187 (10 micromol/L, 5 micromol/L) induced basophil HR in a dose dependent manner, but to different extend with PP1 being the most efficient. CONCLUSIONS: Basophil spontaneous adhesion to Fn is mediated by beta1-integrins whereas cytokine induced adhesion to BSA is mediated by beta2-integrins. PI3K, src-kinases and ERK1/2 play distinct signaling roles in basophil adhesion and HR. PI3K is the key player while ERK1/2 is the weakest participant.

Androstadienes↗
PubMed2006

Allergen-specific IgE testing in the diagnosis of food allergy and the event of a positive match in the bioinformatics search.

Current documents on risk assessment of genetically modified foods recommend including IgE-binding tests on sera from allergic patients. However, there is no generally accepted recommendation on technical aspects of the testing procedures or on the interpretation of the results, despite that fact that both false positive and false-negative results may be caused by variability of the test procedures. The present article discusses the state-of-the-art of serological test procedures for qualitative and quantitative determination of specific IgE and interpretation of test results. It is emphasized that the use of sera from clinically well-characterized subjects is of high importance. In the case of a positive test result, the biological activity of the detected IgE antibodies, i. e., the potential to trigger mediator release from basophils or mast cells in an allergen-specific manner, should be taken into account. However, present data also indicate that validation of such mediator release tests is required, both in terms of experimental protocols and with respect to correlation of the test results with the clinical situation. Further studies are also required to prove the usefulness of targeted serum screening, i. e., the testing of gene products from organisms not known to be allergenic with sera from subjects allergic to related species.

Allergens↗
PubMed2005

IgE-mediated sensitisation, rhinitis and asthma from occupational exposures. Smoking as a model for airborne adjuvants?

OBJECTIVE: Airborne pollutants with adjuvant effect, called airborne adjuvants, may promote IgE-sensitisation and development of allergic airway diseases. Smoking and occupational allergen exposures were reviewed to establish a general and verified framework for hazard identification and risk assessment of adjuvant effects of airborne pollutions. METHODS: The relative risks and the attributable risks of adjuvant effect of smoking were determined for co-exposures with green coffee and castor beans, ispaghula, senna, psyllium, flour and grain dust, latex, laboratory animals, seafood, enzymes, platinum salts, organic anhydrides, or reactive dyes. RESULTS: Adjuvant effects of smoking depended on the types of allergen, but not on whether sensitisation or allergy was promoted by atopy-the hereditarily increased ability to increase IgE formation. CONCLUSION: Promotion of IgE sensitisation in humans and in animals may serve for hazard identification of adjuvant effects. Risk assessment has been based mainly on epidemiological studies, which are sensitive to confounding factors. This highlights the need to develop appropriate animal models for risk assessment.

Adjuvants, Immunologic↗
PubMed2005

The effects of gastric digestion on codfish allergenicity.

BACKGROUND: In a recent murine study, we showed that impaired gastric digestion supports the induction of fish allergy by protecting the digestion-sensitive major allergen parvalbumin and thus enhancing its sensitizing properties. OBJECTIVE: The aim of the present study was to investigate whether impairment of peptic degradation might also play a role in the effector phase of codfish allergy. METHODS: The resistance of cod proteins to digestion by simulated gastric fluid was assessed in vitro . Gastric solutions with pH values ranging from 1.25 to 5.0 were prepared, and the influence of the pH on protein degradation was evaluated by means of SDS-PAGE and IgE immunoblotting. The allergenic potency of digested and undigested cod extract was further characterized in RAST inhibition and basophil histamine release experiments. RESULTS: The digestion experiments revealed that codfish proteins were degraded within 1 minute under physiologic gastric conditions. An only marginal pH shift from 2.5 to 2.75 abrogated completely the digestion of cod allergens. In RAST inhibition experiments digested cod extracts showed a reduced IgE-binding capability that was dependent on the digestion time. Moreover, peptic fragments expressed a 10,000 times reduced allergenic potency, as evaluated on the basis of histamine release from human basophils. CONCLUSION: Codfish allergens have a grossly reduced ability to trigger an intestinal allergic reaction when they are physiologically degraded. Impairment of the physiologic digestion might thus lower the threshold levels of a food allergen in sensitized patients.

Animals↗
PubMed2005

Out-of-season recollection of drug use for seasonal IgE-mediated rhinitis: useful but an overestimation.

BACKGROUND: The history of seasonal, IgE-mediated (allergic) rhinitis is often obtained postseasonally as a retrospective assessment. It is not known whether recollected drug use is representative for the in-seasonal medication history. OBJECTIVES: To investigate the agreement between in-seasonal and out-seasonal reports on drugs and drug doses, and to investigate whether retrospective assessment was sufficiently sensitive to detect the effect of intervention. MATERIAL AND METHODS: Thirty-five patients allergic to birch pollen were allocated to allergen-specific immunotherapy (SIT) or placebo in a double-blind study. Drug use was recorded daily during the season 2000 and out-seasonally 6 months after the seasons 1999 and 2000. The mean daily drug use was transformed into a 4-point categorical scale for simplicity and was calculated for the out-seasonal rating and for 6 in-seasonal periods of different durations. In-seasonal and postseasonal ratings were compared with the Cohen weighted kappa (kappa w). RESULTS: We observed a high level of agreement between in-seasonal and retrospective reports of drugs used (kappa w > 0.60) and drug doses (kappa w > 0.50). The highest agreement was observed for the in-seasonal day, week, or 2 weeks with the highest drug intake. Out-seasonal ratings significantly overestimated the daily oral and nasal antihistamine use compared with in-seasonal periods >2 weeks. Despite being comparable pretreatment, only the SIT group had a significant decrease in recollected total drug use during SIT. CONCLUSION: Out-seasonal recollection of hay fever drugs represented a period of a maximum 14 days. It appeared sufficiently sensitive to detect the effect of intervention.

Adult↗
PubMed2005

Locked nucleic acid inhibits amplification of contaminating DNA in real-time PCR.

Locked nucleic acid (LNA) is a modified DNA with increased binding affinityfor complementary DNA sequences. Our strategy was to use this property of LNA to inhibit undesired PCR amplification (e.g.,from contaminating genomic DNA) in a cDNA-based assay. By placing a short complementary LNA sequence in intronic DNA, the aim was to inhibit the amplification of genomic DNA without affecting the amplification of reverse-transcribed spliced mRNA. LNA was designed to bind within intron 5 in the x-box binding protein 1 (XBP1) gene. An irrelevant LNA oligonucleotide served as a negative control. In both PCR and real-time PCR, the addition of LNA showed blocking of the amplification of genomic XBP1 but not cDNA XBP1. To test the effect of melting temperature (Tm) on the LNA, we investigated the number of LNA nucleotides that could be replaced with DNA nucleotides and still retain the blocking activity. More than three DNA nucleotides reduced the LNA inhibition ability. The sequence specificity of the LNA was tested by investigating the number of LNA nucleotide mismatches permitted. The introduction of one mismatch maintained the inhibition of genomic amplification whereas two mismatches reduced the amplification. Our results show that LNA may be used to enhance the specificity of PCR by eliminating unwanted PCR products.

Base Pair Mismatch↗
PubMed2004

[Allergy tests].

Explore the source record for details and available documents.

Adult↗
PubMed2004

Evaluation of the potential allergenicity of the enzyme microbial transglutaminase using the 2001 FAO/WHO Decision Tree.

All novel proteins must be assessed for their potential allergenicity before they are introduced into the food market. One method to achieve this is the 2001 FAO/WHO Decision Tree recommended for evaluation of proteins from genetically modified organisms (GMOs). It was the aim of this study to investigate the allergenicity of microbial transglutaminase (m-TG) from Streptoverticillium mobaraense. Amino acid sequence similarity to known allergens, pepsin resistance, and detection of protein binding to specific serum immunoglobulin E (IgE) (RAST) have been evaluated as recommended by the decision tree. Allergenicity in the source material was thought unlikely, since no IgE-mediated allergy to any bacteria has been reported. m-TG is fully degraded after 5 min of pepsin treatment. A database search showed that the enzyme has no homology with known allergens, down to a match of six contiguous amino acids, which meets the requirements of the decision tree. However, there is a match at the five contiguous amino acid level to the major codfish allergen Gad c1. The potential cross reactivity between m-TG and Gad c1 was investigated in RAST using sera from 25 documented cod-allergic patients and an extract of raw codfish. No binding between patient IgE and m-TG was observed. It can be concluded that no safety concerns with regard to the allergenic potential of m-TG were identified.

Animals↗
PubMed2004

Allergy assessment of foods or ingredients derived from biotechnology, gene-modified organisms, or novel foods.

The introduction of novel proteins into foods carries a risk of eliciting allergic reactions in individuals sensitive to the introduced protein and a risk of sensitizing susceptible individuals. No single predictive test exists to perform a hazard assessment in relation to allergenic properties of newly expressed proteins in gene-modified organisms (GMOs). Instead, performance of a weighted risk analysis based on the decision tree approach has been suggested. The individual steps of this analysis comprise sequence homology to known allergens, specific or targeted serum screens for immunoglobulin E (IgE) cross-reactions to known allergens, digestability studies of the proteins in simulated gastric and/or intestinal fluids, and animal studies. These steps are discussed and five examples of risk evaluation of GMOs or novel foods are presented. These include ice-structuring protein derived from fish, microbial transglutaminase, GMO-soybeans, amylase and the Nangai nut.

Allergens↗