Biomedical subjects

L K Poulsen

Publications and source records attributed to L K Poulsen.

At least 19 recordsLinked to original sources

PubMed2006

Lack of immunogenicity of ice structuring protein type III HPLC12 preparation administered by the oral route to human volunteers.

Before a novel protein can be used in foods, its potential allergenicity must be assessed. In this study, healthy volunteers consumed ice structuring protein (ISP) Type III preparation or a control material 5 days a week for a total of 8 weeks. General measures of health were recorded during the study, and the immunogenicity of the protein was assessed by monitoring the levels of IgG and IgE antibodies specific for ISP Type III. The participants remained in good health throughout the study and during the 4 week follow-up period. No IgG or IgE antibodies specific for ISP Type III were detected in the blood of the participants. Investigations of immunogenicity in man have not been previously applied in the context of safety evaluation and they do not form part of the regimens proposed for the evaluation of protein allergenicity. Consequently no standardised protocols exist for such studies, nor any background against which to interpret the results. Nevertheless, the absence of an immune response using a protocol which could have been expected to result in a response with a strongly immunogenic protein, confirms the conclusions of earlier published work, and attests to the lack of allergenicity of ISP Type III preparation.

Adjuvants, Immunologic↗

PubMed2006

Immunological characteristics of subjects with asymptomatic skin sensitization to birch and grass pollen.

BACKGROUND: Asymptomatic skin sensitization (AS) has been shown to be a risk factor for respiratory allergic disease. OBJECTIVE: We investigated allergen and recall antigen-driven T cell proliferation, cytokine production and T cell expression of the chemokine receptor CCR4, in cultures derived from symptomatic atopics (SA), subjects with AS and healthy controls (HC). Numbers of allergen-specific precursor T cells in all three groups were also estimated. METHODS: Peripheral blood mononuclear cells from the three groups were isolated and stimulated with allergen and tetanus toxoid. Proliferation, cytokine production and CCR4 expression were measured by flow cytometry. RESULTS: A significantly increased proportion of CD4(+) memory T cells proliferated in response to allergen in SA as compared with subjects with AS (P<0.001) and HC (P<0.001). Only in SA was expansion of CD4(+)CCR4(+) T cells, after allergen stimulation observed. SA had higher frequencies of allergen-specific T cells than subjects with AS and HC (P=0.02, for both). With regard to allergen-induced production of T-helper type 1 (Th1) and Th2 cytokines, subjects with AS and HC resembled each other, while differing significantly from SA. CONCLUSION: We conclude, that subjects with AS, although clearly IgE sensitized, have significant diminished numbers of allergen-specific T cells as well as decreased allergen-induced CD4(+) memory T cell proliferation as compared with SA. To a large extent, our findings are capable of explaining the immunological characteristics associated with AS. Our findings may serve as better prognostic markers for subsequent allergic progression, than previously described clinical and paraclinical characteristics.

Adult↗

PubMed2006

Class switch recombination in selective IgA-deficient subjects.

Selective IgA deficiency is a common immunodeficiency in Caucasians, but the molecular basis of the disorder remains elusive. To address this issue we examined the molecular events leading to IgA production. Naive IgD positive B cells were purified from four donors with IgA deficiency and four control donors, all Caucasians. Stimulation of B cells from IgA-deficient donors with the cytokines transforming growth factor (TGF)-beta, interferon (IFN)-gamma or interleukin (IL)-10 in the presence of anti-CD40 antibodies showed reduced expression of both activation-induced cytidine deaminase (AID) and alpha germline transcripts (GLT) compared to controls. It was possible, however, to induce AID and alpha GLT when stimulating the cells with anti-CD40 antibody and TGF-beta in the combination with IL-10. Moreover, in anti-CD40 antibody-stimulated cultures, addition of IL-10 or IL-10 + TGF-beta in combination, induced IgA production, albeit lower than found in B cells from controls. The B cells from the IgA-deficient subjects were less effective in differentiating into CD138(+) X-box binding protein 1 (XBP-1)(+) plasma cells when stimulated with TGF-beta, IFN-gamma or IL-10. Interestingly, when adding IL-4 to TGF-beta alone or in combination with IL-10, the immunoglobulin production in B cells from IgA-deficient donors was comparable with those of normal controls. These data show that in healthy subjects in vitro IgA production can be up-regulated by addition of IL-10 to CD40-stimulated B cells, whereas a similar B cell differentiation does not occur in IgA-deficient subjects. Addition of IL-4, however, reverts this abnormality.

Adult↗

PubMed2006

The role of the interleukin-10 subfamily members in immunoglobulin production by human B cells.

Interleukin (IL)-10 has been shown to have various effects on B cells, including positively affecting the production of immunoglobulin A (IgA) and IgG. Several human IL-10-related molecules have been identified. These include IL-19, IL-20, IL-22, IL-24, IL-26, IL-28 and IL-29. To determine the effects of the IL-10 analogues on the class switch recombination in B cells, we analysed Ig production from naïve B cells stimulated with these cytokines in the presence of anti-CD40. None of the cytokines were found to induce Ig production by themselves in the presence of anti-CD40 Ab. However, all cytokines inhibited the production of IgA and IgG induced by anti-CD40 Ab alone. In combination with anti-CD40 Ab and IL-4, IgG4 were inhibited in cultures stimulated with IL-20, IL-22, IL-26, IL-28 and IL-29 compared with IL-4 and anti-CD40 Ab alone, whereas all IL-10 analogues increased the production of total IgG. All analogues reduced anti-CD40 Ab + transforming growth factor (TGF)-beta-induced IgA production compared with cultures stimulated with anti-CD40 Ab and TGF-beta alone. Together, these data show that the IL-10-related cytokines in combination with anti-CD40 Ab are not by themselves directly involved in the Ig regulation in B cells. However, some of the analogues might have regulatory effects on CSR induced by CD40-ligation in combination with IL-4 or TGF-beta.

Animals↗

PubMed2006

Are basophil histamine release and high affinity IgE receptor expression involved in asymptomatic skin sensitization?

BACKGROUND: Immunoglobulin (Ig)E-sensitized persons with positive skin prick test, but no allergy symptoms, are classified as being asymptomatic skin sensitized (AS). The allergic type 1 disease is dependant on IgE binding to the high affinity IgE-receptor (FcepsilonRI) expressed on basophils and mast cells. However, a relationship between the AS status and FcepsilonRI has not been investigated. We aimed to characterize basophils from AS by looking at histamine release (HR) (sensitivity and reactivity) and the FcepsilonRI molecule, and compare it with nonatopic (NA) or allergic (A) persons. METHODS: Blood was obtained from NA (n = 14), grass and/or birch A persons (n = 17) and mono-sensitized grass or birch pollen AS (n = 12). The basophil sensitivity and reactivity were examined by anti-IgE triggered HR. Surface expression of FcepsilonRI and IgE were measured by flow cytometry, FcepsilonRIalpha protein was identified using a radioimmunoassay and Western blot. mRNA coding for the classic FcepsilonRIbeta-chain and the truncated form (FcepsilonRIbetaT) were determined by real-time PCR. RESULTS: The AS group was less reactive than NA or A persons when triggered by anti-IgE and had a significant higher number of nonresponders. However, there was no difference in sensitivity among the three groups and furthermore; the groups did not vary in FcepsilonRI- and IgE-surface expression, FcepsilonRIalpha-protein level or beta/betaT ratio. CONCLUSION: Basophils from AS persons are less reactive and include more nonresponders than basophils from NA and A persons, but do not differ regarding the FcepsilonRI molecule.

Adult↗

PubMed2006

Seasonal dynamics of chemokine receptors and CD62L in subjects with asymptomatic skin sensitization to birch and grass pollen.

BACKGROUND: Asymptomatic skin sensitization (AS) has been shown to be a risk factor for respiratory allergic disease. CCR4, CXCR1 and CD62L have all been assigned a role in the immunopathogenesis of allergy. Memory T-cell expression of CCR4, CXCR1 and CD62L has not hitherto been investigated in subjects with AS. METHODS: We investigated seasonal CD4 memory T-cell expression of the chemokine receptors CCR4, CXCR1 as well as L-selectin (CD62L) in fresh cultures derived from symptomatic atopics (SAs), subjects with AS and healthy controls (HCs). Peripheral blood mononuclear cells from all three groups were isolated during birch and grass pollination as well as in the following winter. CD4 memory T-cell expression of CCR4, CXCR1 and CD62L was determined by flow-cytometry. RESULTS: During spring and summer, a significantly increased proportion of memory T cells expressed CCR4, CXCR1 and CD62L in SAs when compared with subjects with AS and HCs. Only SAs exhibited seasonal fluctuations in numbers of CCR4, CXCR1 and CD62L positive memory T cells. CONCLUSION: Although clearly IgE sensitized, subjects with AS have significant diminished numbers of CCR4, CXCR1 and CD62L positive memory T cells, during pollination, when compared with SAs. In contrast to SAs, cultures derived from subjects with AS did not display seasonal variation. Our findings explain the lack of clinical symptoms, during pollination, in subjects with AS.

Allergens↗

PubMed2006

Rhinitis symptoms and IgE sensitization as risk factors for development of later allergic rhinitis in adults.

BACKGROUND: Rhinitis symptoms and IgE-sensitization often mismatch. Asymptomatic sensitization is an established risk factor for later rhinitis, whereas it is not clear whether rhinitis is a risk factor for later development of IgE-sensitization. OBJECTIVE: To investigate whether nonallergic rhinitis is a risk factor for later development of IgE-sensitization in adults during an 8-year follow-up period, and whether asymptomatic sensitization is a risk factor for later development of rhinitis. METHODS: In a population-based study of 15-69 years olds in 1990, 734 subjects were re-examined in 1998. On both occasions questionnaires on rhinitis symptoms were completed and serum IgE (against birch, grass, mugwort, cat, dog, and Dermatophagoides pteronyssinus) were determined (positive if >or=0.35 kUA/l). Asymptomatic sensitization: positive IgE levels without any rhinitis symptoms. Nonallergic rhinitis: rhinitis symptoms and no sensitization. RESULTS: Asymptomatic sensitization to pollens, pets, or house dust mite was significantly associated with onset of rhinitis symptoms, also when changing baseline cut-off for sensitization to >or=0.1 or >or=0.7 kUA/l. The 8-year incidence of pollen-related rhinitis was 15.1% and 2.6% in subjects sensitized and nonsensitized to pollens, respectively (odds ratio 6.1, 95% CI 2.3-16.0). Persistent or intermittent nonallergic rhinitis was not significantly associated with later sensitization, yet a positive trend for development was observed in nonallergic pollen-related rhinitis. CONCLUSION: Asymptomatic sensitization but not nonallergic rhinitis was a significant risk factor for later development of allergic rhinitis.

Adolescent↗

PubMed2006

Safety and tolerability of grass pollen tablets in sublingual immunotherapy--a phase-1 study.

BACKGROUND: A single-centre, randomized, double-blind, placebo-controlled study. AIMS: To compare the safety and tolerability of four different sublingual immunotherapy (SLIT) regimes in grass pollen allergic rhinitis. METHODS: Thirty subjects sensitized to grass pollen were enrolled and allocated to four groups. Sublingual immunotherapy was administered in tablets daily for 10 days. Groups 1 and 2 received incremental sublingual doses of 100, 200, 300, 400 and 500 IR, Group 1 daily and Group 2 increments every second day. Repeated constant dose regimens of 300 IR and 500 IR were administered in Groups 3 and 4 respectively. Safety assessments included adverse events (AE), vital signs, electrocardiogram (ECG) and clinical laboratory tests. RESULTS: Sublingual immunotherapy 300 IR (Group 3) administered in a constant dose and incremental doses up to 500 IR (Groups 1 and 2) were generally well tolerated. The majority of AEs were mild to moderate, the most common being oral pruritus, throat irritation and swollen tongue. Severe local AEs (swelling of throat) were observed only for Group 4. No serious systemic AEs were reported. There were no relevant changes in clinical laboratory, vital signs and ECG data. CONCLUSION: Adverse events were mostly local (sublingual), were not severe and resolved rapidly. Using a 5-day induction regimen high-dose treatment up to 500 IR could be administered without important side-effects, in contrast to initiating with a constant dose of 500 IR. The data indicate that a short dose increase phase may reduce the incidence of AEs when high-dose SLIT is administered.

Administration, Sublingual↗

PubMed2005

A comparative study of the FcepsilonRI molecule on human mast cell and basophil cell lines.

BACKGROUND: Mast cells and basophils express the high-affinity IgE receptor FcepsilonRI. We have analysed the human mast cell line LAD2 and four subclones of the basophil cell line KU812 in order to reveal possible differences concerning the FcepsilonRI surface regulation, anti-IgE-triggered activation, FcepsilonRIalpha protein stability and the mRNA level of FcepsilonRIalpha-, beta- and the truncated beta-chain (beta(T)), and thereby determine the utility of these cell lines in investigations of the FcepsilonRI biology. METHODS: The surface expression of FcepsilonRI was assessed by flow cytometry, using the monoclonal antibody CRA1. The FcepsilonRI-induced cellular activation (i.e. cross-linking of FcepsilonRI) was determined by changes in the intracellular level of Ca2+, which was measured by fluorescence of Fura-2. The level of the FcepsilonRIalpha protein was determined by a Western blot technique and by a radioimmunoassay. The mRNA level of FcepsilonRIalpha, beta- and beta(T)-chain was analysed using real-time PCR. RESULTS: Two KU812 subclones and especially LAD2 had FcepsilonRI surface expression which was capable of inducing cellular activation. Both the FcepsilonRI expression and stability of the FcepsilonRIalpha protein were increased when IgE was present. All the cell lines expressed mRNA of FcepsilonRIalpha-, beta- and beta(T), with LAD2 tending to have the highest expression. However, a determination of the beta/beta(T) ratio demonstrated no difference between any of the cell clones. CONCLUSION: These cell lines are important tools in the investigation of both the FcepsilonRI molecule and the effects induced by its activation.

Basophils↗

PubMed2005

Is immunotherapy-induced birch-pollen-specific IgG4 a marker for decreased allergen-specific sensitivity?

BACKGROUND: The role of IgG4 during allergen-specific immunotherapy (SIT) is still controversial. The available studies present paramount differences in in vitro techniques, allergens, and clinical outcome parameters. By implementing a sensitive method, and pivotal clinical outcome parameters, we wanted to ascertain the utility of IgG4 as a clinical marker of decreased allergen-specific sensitivity to a common aeroallergen. METHODS: Sera were drawn from 23 birch-pollen-allergic patients during a placebo-controlled clinical trial on birch pollen SIT. Seventeen patients received active treatment. Blood samples were drawn at 0, 2, 4, 7, and 30 treatment weeks, and 36 months. The binding activity of autologous IgG, IgG4, IgE, and IgE- and/or IgG-depleted serum to (125)I-labelled recombinant Bet v 1 was assessed in a fluid-phase radioimmunoassay. Disease severity was assessed subjectively on a visual analogue scale (VAS), and objectively by intradermal late-phase reaction diameters. RESULTS: Before SIT IgG4 fraction of IgG-allergen binding varied from 4 to 74%, with a median of 36%, increasing to 71% after 36 months. Changes in IgG4 or IgG4/IgG fraction were not correlated to clinical outcome parameters. Changes in IgG allergen binding and VAS were significantly correlated (sigma = 0.72; p < 0.05). SIT increased the serum-blocking activity of IgE allergen binding from 25% before SIT to 80% after SIT. No changes were observed in the placebo group. CONCLUSION: The data suggest that IgG4 per se is a poor marker of decreased allergen-specific sensitivity to birch pollen, both as a single measurement and as delta values.

Betula↗

PubMed2005

Vaccination for birch pollen allergy: comparison of the affinities of specific immunoglobulins E, G1 and G4 measured by surface plasmon resonance.

BACKGROUND: Allergen-specific immunotherapy (SIT) is associated with increased levels of allergen-specific IgG in serum. However, it is not clear to what extent qualitative changes in the allergen binding capacity of IgG may be induced as well. OBJECTIVE: The purpose of this study was to investigate the influences of SIT on antibody affinity. METHODS: The binding affinity of purified serum IgG1, IgG4 and IgE to the major allergen in birch (Betula verrucosa) pollen, Bet v 1, was analysed by surface plasmon resonance. The antibodies were obtained from 10 birch pollen-allergic patients receiving SIT and from 10 patients with no SIT. RESULTS: The patients having received SIT have a significant higher titre of anti-Bet v 1 antibodies in their blood, but the affinity to Bet v 1 of allergen-specific IgE, IgG1 and IgG4 does not differ between the two groups. For IgG1 and IgG4, correlations between less allergic symptoms and affinity of the antibodies were observed both in the SIT group and to a smaller extent in the non-SIT group. CONCLUSION: SIT has no effect on antibody affinity of allergen-specific IgE, IgG1 or IgG4. Allergic patients with high-affinity IgG1 and IgG4 antibodies report less symptoms than patients with low-affinity antibodies.

Adult↗

PubMed2005

In search of a new paradigm: mechanisms of sensitization and elicitation of food allergy.

In this review of research priorities, presented for the European Commission, food allergy is established as a disease with a considerable impact on modern society. Research paradigms have changed from establishing basic symptomatology and diagnostic methods over allergen characterization to a risk-identification approach looking at which patients are at risk of developing reactions to a certain dose of allergenic food. In order to solve some of the apparent paradoxes of regional, temporal, and species-related differences in sensitization and food allergic reactions, it is suggested to study the basic underlying mechanisms in the cross-field between immunology and gastroenterology. Research priorities should include the molecular basis of cross-reactivity, the digestion and maintenance of antigenicity, the genetics of food allergy, and the immune response to food antigens and effects on the gastrointestinal immune system by food matrices and the microbial gut-flora. Necessary methods with be spanning from molecular biology to large-scale clinical and epidemiological studies.

Antibody Formation↗

PubMed2005

Validation of basophil histamine release against the autologous serum skin test and outcome of serum-induced basophil histamine release studies in a large population of chronic urticaria patients.

BACKGROUND: Endogenous histamine-releasing factors (HRFs) are involved in 30-60% of patients with chronic urticaria (CU). Evidence for their existence comes from in vivo studies of autoreactivity with the autologous serum skin test (ASST), in vitro immunoassays demonstrating autoantibodies against the immunoglobulin E (IgE) or the high affinity IgE receptor (FcepsilonRI) and serum-induced histamine release (HR) from basophils and mast cells. We have examined the correlation between the ASST and a new basophil histamine-releasing assay (the HR-Urtikaria test) in a group of well-characterized CU patients and subsequently determined the frequency of HR-Urticaria-positive sera from a larger population of CU patients. SUBJECTS: Group 1 consisted of 28 patients with CU (16 were ASST-positive) 20 patients with atopic dermatitis, 24 patients with allergy to birch and nine healthy controls. Group 2 consisted of 873 unselected CU patients. METHODS: White blood cells containing 1-2% basophils from a healthy nonatopic donor were incubated with patients sera in the presence of interleukin (IL)-3. Histamine was measured by the glass fibre method. RESULTS: Using the ASST as the true outcome, the HR-Urticaria test showed a sensitivity and specificity of 75% in group 1 using a cut-off value for HR of >16.5%. None of the controls was positive in the HR-Urticaria test. In group 2, we found no difference in the frequency of positives between male (34.6%, n = 254) and female adults (35.1%, n = 576) but twice as many females as males were tested. CONCLUSIONS: Our studies have shown that the HR-Urticaria test has a good sensitivity and specificity for endogenous HRFs demonstrated by the ASST in patients with CU and that about one-third of unselected patients with CU have a positive result.

Adolescent↗

PubMed2005

Double blind placebo controlled exposure to molds: exposure system and clinical results.

UNLABELLED: The objective was to develop an experimental setup for human exposure to mold spores, and to study the clinical effect of this exposure in sensitive subjects who had previously experienced potentially building-related symptoms (BRS) at work. From three water-damaged schools eight employees with a positive histamine release test to Penicillium chrysogenum were exposed double- blinded to either placebo, approximately 600,000 spores/m3 air of P. chrysogenum or approximately 350,000 spores/m3 of Trichoderma harzianum for 6 min on three separate days. A statistically significant rise in symptoms from mucous membranes appeared from the 9-graded symptom scale after exposure to T. harzianum or placebo. Dichotomizing the data, whether the participants experienced at least a two-step rise on the symptom scale or not, gave borderline increase in mucous membrane symptoms after exposure to P. chrysogenum. In conclusion this is, to our knowledge, the first study to successfully conduct a human exposure to a highly controlled dose of fungal material aerosolized directly from wet building materials. This short-term exposure to high concentrations of two different molds induced no more reactions than exposure to placebo in eight sensitive school employees. However, a statistical type II error cannot be excluded because of the small sample size. PRACTICAL IMPLICATIONS: In this double blind, placebo controlled study of mold exposure changes in symptoms, objective measurements and blood samples were small and mostly non-significant, and at the same level as after placebo exposure. The developed exposure system based on the Particle-Field and Laboratory Emission Cell (P-FLEC) makes it possible to deliver a precise and highly controlled dose of mold spores from water-damaged building materials, imitating realistic field exposure conditions. The present experiment is too small to rule out an effect of mold exposure; long-term experimental exposure studies on larger number of subjects are needed.

Adult↗

PubMed2004

Clinical efficacy of sublingual and subcutaneous birch pollen allergen-specific immunotherapy: a randomized, placebo-controlled, double-blind, double-dummy study.

BACKGROUND: Both sublingual allergen-specific immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT) have a documented clinical efficacy, but only few comparative studies have been performed. OBJECTIVE: To investigate the clinical efficacy of SLIT vs SCIT and secondary to compare SLIT and SCIT with placebo and to evaluate the relative clinical efficacy in relation to systemic side-effects. METHODS: A 3-year randomized, placebo-controlled, double-blind, double-dummy study including 71 adult birch pollen hay fever patients treated for two consecutive years after a baseline year. Allocation to treatment groups was based on disease severity in the baseline season, gender and age. RESULTS: Clinical efficacy was estimated in 58 patients completing the first treatment year by subtracting baseline data and by calculating the ratio first treatment season vs baseline. SLIT diminished the median disease severity to one-half and SCIT to one-third of placebo treatment. No statistical significant difference between the two groups was observed. Both for symptoms and medication scores actively treated patients showed statistically significant and clinical relevant efficacy compared with placebo. SLIT treatment only resulted in local mild side-effects, while SCIT resulted in few serious systemic side-effects. CONCLUSION: Based on the limited number of patients the clinical efficacy of SLIT was not statistically different from SCIT, and both treatments are clinically effective compared with placebo in the treatment of birch pollen rhinoconjunctivitis. The lack of significant difference between the two treatments does not indicate equivalent efficacy, but to detect minor differences necessitates investigation of larger groups. Due to the advantageous safety profile SLIT may be favored.

Administration, Sublingual↗

PubMed2004

Cross-reactivity to eel, eelpout and ocean pout in codfish-allergic patients.

Fish allergy is one of the most common food allergies in both children and adults and patients with allergic reactions to one fish species have in many cases been given the advice to avoid all fish, without further evaluation. The possible common reactivity between different fish species is not well studied. Because of this and a possible exploitation of fish species hitherto not much used in the Scandinavian diet ocean pout, eelpout and eel were evaluated. We examined the serological and biological cross-reactivity of these species in double-blind challenged-confirmed codfish-allergic patients using CAP, Maxisorp-radio allergosorbent test (RAST) inhibition, western blot, skin prick test (SPT) and histamine release (HR). All 18 codfish allergic patients had specific IgE to ocean pout, eelpout and eel determined by Maxisorp-RAST. All four fish species could induce basophil HR using blood from 16 of 18 patients and all patients tested reacted in SPT. This study demonstrates that patients with a verified clinical allergy to codfish in a high frequency express biological cross-reactivity to other fish species. By RAST inhibition this common reactivity was shown to be a true cross-reactivity.

Adolescent↗

PubMed2003

Assessment of the potential allergenicity of ice structuring protein type III HPLC 12 using the FAO/WHO 2001 decision tree for novel foods.

The introduction of novel proteins into foods carries a risk of eliciting allergic reactions in individuals sensitive to the introduced protein. Therefore, decision trees for evaluation of the risk have been developed, the latest being proposed by WHO/FAO early in 2001. Proteins developed using modern biotechnology and derived from fish are being considered for use in food and other applications, and since allergy to fish is well established, a potential risk from such proteins to susceptible human beings exists. The overall aim of the study was to investigate the potential allergenicity of an Ice Structuring Protein (ISP) originating from an arctic fish (the ocean pout, Macrozoarces americanus) using the newly developed decision tree proposed by FAO/WHO. The methods used were those proposed by FAO/WHO including amino acid sequence analysis for sequence similarity to known allergens, methods for assessing degradability under standardised conditions, assays for detection of specific IgE against the protein (Maxisorb RAST) and histamine release from human basophils. In the present paper we describe the serum screening phase of the study and discuss the overall application of the decision tree to the assessment of the potential allergenicity of ISP Type III. In an accompanying paper [Food Chem. Toxicol. 40 (2002) 965], we detail the specific methodology used for the sequence analysis and assessment of resistance to pepsin-catalysed proteolysis of this protein. The ISP showed no sequence similarity to known allergens nor was it stable to proteolytic degradation using standardised methods. Using sera from 20 patients with a well-documented clinical history of fish allergy, positive in skin prick tests to ocean pout, eel pout and eel were used, positive IgE-binding in vitro to extracts of the same fish was confirmed. The sera also elicited histamine release in vitro in the presence of the same extracts. The ISP was negative in all cases in the same experiments. Using the proposed decision tree, we demonstrated the safety of the ISP to patients already sensitised to fish, as well as to individuals potentially susceptible to producing IgE responses to proteins. Furthermore, the practicability of the new decision tree was confirmed.

Adolescent↗

PubMed2003

Roasted hazelnuts--allergenic activity evaluated by double-blind, placebo-controlled food challenge.

BACKGROUND: Allergy to hazelnuts is a common example of birch pollen related food allergy. Symptoms upon ingestion are often confined to the mouth and throat, but severe systemic reactions have been described in some patients. The aim of the study was to evaluate the reduction in allergenicity by roasting of the nuts. METHODS: Double-blind, placebo-controlled food challenges (DBPCFC) with roasted hazelnuts (140 degrees C, 40 min) were performed in 17 birch pollen allergic patients with DBPCFC-confirmed food allergy to raw hazelnuts. The effect of roasting was further evaluated by skin prick test (SPT), histamine release (HR), measurement of specific IgE, and IgE-inhibition experiments. RESULTS: In 5/17 patients the DBPCFC with the roasted nuts were positive. The symptoms were generally mild and included OAS (oral allergy syndrome) in all patients. Roasting of the nuts significantly reduced the allergenic activity evaluated by SPT, HR, specific IgE, and IgE-inhibition. Immunoblotting experiments with recombinant hazelnut allergens showed sensitization against Cor a 1.04 in 16/17 patients and against Cor a 2 in 7/17 patients. None of the patients were sensitized to Cor a 8. Challenge-positive patients did not differ from the rest in IgE-binding pattern. CONCLUSIONS: All the applied methods indicated that roasting of hazelnuts reduces the allergenicity, but since 5/17 birch pollen allergic patients were DBPCFC-positive to the roasted nuts, ingestion of roasted hazelnuts or products containing roasted hazelnuts can not be considered safe for a number of hazelnut allergic consumers. For patients with a history of severe allergic symptoms upon ingestion of hazelnuts, thorough and conscientious food labelling of hazelnuts and hazelnut residues is essential.

Adolescent↗