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Biomedical subjects

E F Knol

Publications and source records attributed to E F Knol.

At least 19 recordsLinked to original sources
PubMed2007

Role of human leucocyte antigen DQ in the presentation of T cell epitopes in the major cow's milk allergen alphas1-casein.

BACKGROUND: Little is known about the association between human leucocyte antigen (HLA) and cow's milk allergy (CMA). The aim of the present study was to determine the HLA restriction of T cell clones (TCCs) specific to alphas1-casein, the most abundant milk protein, and to study possible HLA class II allele associations with CMA. METHODS: alphas1-Casein-specific TCCs were derived from 6 children with CMA, 9 atopic children without CMA and 5 non-atopic children. T cell epitope specificity was defined by stimulation with overlapping peptides, spanning the alphas1-casein molecule. HLA restriction was determined in proliferation assays using antibodies blocking either HLA-DP, HLA-DQ or HLA-DR. HLA genotyping was performed in 32 subjects with CMA, 23 atopic and 22 non-atopic individuals. RESULTS: Ten TCCs were restricted to HLA-DQ, 6 TCCs to HLA-DR and 4 TCCs to HLA-DP. The sequence in alphas1-casein that was most immunogenic to T cells from children with CMA contained T cell epitopes restricted to DQB1*0201, DPB1*0401 and DRB1*1501. The DQB1*0501 allele frequency was lower in children with CMA than in non-atopic children, but this difference could not be confirmed in an additional group of subjects with and without CMA. CONCLUSIONS: HLA-DQ plays a substantial role in the presentation of T cell epitopes in alphas1-casein. However, HLA class II allele frequencies do not show major differences between cow's milk allergic, atopic and non-atopic subjects. T cell epitopes in the most immunogenic region are presented by various abundantly present HLA genotypes. Therefore, this sequence may be a suitable target for peptide immunotherapy.

Adolescent↗
PubMed2007

Does skin prick test reactivity to purified allergens correlate with clinical severity of peanut allergy?

BACKGROUND: Recognition of specific peanut allergens or the diversity of IgE binding to peanut allergens may play a role in the elicitation of severe allergic reactions. OBJECTIVE: To investigate whether sensitization to individual allergens Ara h 1, Ara h 2, Ara h 3 and Ara h 6 is correlated with clinical severity. METHODS: The reactivity of purified peanut allergens was measured by skin prick test (SPT) and by IgE immunoblot in 30 patients. The results were related to the clinical reactivity by history, and in 25 of them to the eliciting dose (ED). RESULTS: The majority of patients recognized Ara h 2 and Ara h 6. Patients with severe symptoms had a higher SPT response to Ara h 2 and Ara h 6 at low concentrations (0.1 micro g/mL) and to Ara h 1 and Ara h 3 at higher concentrations (100 micro g/mL), compared with patients with mild symptoms. They also recognized a greater number of allergens and showed a higher cumulative SPT response compared with patients with mild symptoms. No significant differences were observed between patients with a low or high ED. CONCLUSIONS: Ara h 2 and Ara h 6 appeared to be more potent than Ara h 1 and Ara h 3. Both SPT reactivity to low concentrations of Ara h 2 and Ara h 6 and to higher concentrations of Ara h 1 and Ara h 3 were shown to be indicative of severe symptoms.

2S Albumins, Plant↗
PubMed2007

The interleukin-10 inducing effect of transforming growth factor-beta on human naive CD4+ T cells from cord blood is restricted to the TH1 subset.

Transforming growth factor (TGF-beta) seems to play a role in the regulation of immune responses, mainly by its suppressive function towards cells of the immune system. However, both in mice and human, conflicting data are published on the capacity of TGF-beta to induce interleukin (IL)-10 secretion in both naive and skewed T cell populations. Our aim was to test the IL-10-inducing capacity of TGF-beta in both naive and skewed cord blood mononuclear cells (CBMCs) and elucidate the mechanism by which TGF-beta exerts its effect. Therefore, naive CBMCs and CBMCs during skewing under T helper 1 (Th1) and Th2 polarizing conditions were stimulated with CD3 and/or CD28 in the presence or absence of TGF-beta. Proliferation, cytokine production and mRNA expression of transcription factors was measured. TGF-beta enhanced the IL-10 production in Th1 and naive cells only, and suppressed the T(H)1 phenotype as demonstrated in cytokine levels and T-box expression in T cells (T-bet) expression. Interestingly, forkhead box p3 (Foxp3) expression tended to increase in both Th1 and Th2 cells. These data indicate that TGF-beta can induce a regulatory phenotype in both naive and Th1-polarized cells derived from cord blood. The induction of IL-10 was not observed in Th2-polarized phenotype, indicating that TGF-beta might be especially of interest for immunomodulation in Th1 cells.

Antigens, CD↗
PubMed2007

Variance component analysis of quantitative trait loci for pork carcass composition and meat quality on SSC4 and SSC11.

In a previous study, QTL for carcass composition and meat quality were identified in a commercial finisher cross. The main objective of the current study was to confirm and fine map the QTL on SSC4 and SSC11 by genotyping an increased number of individuals and markers and to analyze the data using a combined linkage and linkage disequilibrium analysis method. A modified version of the method excludes linkage disequilibrium information from the analysis, enabling the comparison of results based on linkage information only or results based on combined linkage and linkage disequilibrium information. Nine additional paternal half-sib families were genotyped for 18 markers, resulting in a total of 1,855 animals genotyped for 15 and 13 markers on SSC4 and SSC11, respectively. The QTL affecting meat color on SSC4 was confirmed, whereas the QTL affecting LM weight could not be confirmed. The combined linkage and linkage disequilibrium analysis resulted in the identification of new significant effects for 14 traits on the 2 chromosomes. Heritabilities of the QTL effects ranged from 1.8 to 13.2%. The analysis contributed to a more accurate positioning of QTL and further characterized their phenotypic effect. However, results showed that even greater marker densities are required to take full advantage of linkage disequilibrium information and to identify haplotypes associated with favorable QTL alleles.

Adipose Tissue↗
PubMed2006

No effect of anti-interleukin-5 therapy (mepolizumab) on the atopy patch test in atopic dermatitis patients.

BACKGROUND: The atopy patch test (APT) is an in vivo model to study the induction of eczema by inhalant allergens in atopic dermatitis (AD) patients. Mepolizumab is a monoclonal antibody to interleukin-5, which reduces peripheral blood eosinophils. Previously, we reported that mepolizumab treatment did not result in clinical improvement in AD. The current study investigates the effect of mepolizumab therapy on the APT in the same patients. METHODS: Mepolizumab treatment was given at days 0 and 7 in a double-blind placebo-controlled design. The APT was applied at days -2, 0, 14 and 28. Clinical evaluation of each APT was conducted 48 h after application at days 0, 2, 16 and 30. Skin biopsies were taken at days 0, 2 and 16 for eosinophil counts. RESULTS: The mepolizumab-treated group showed no significant reduction in macroscopic outcome of the APT. Tissue eosinophils were reduced in the mepolizumab-treated group at day 16 compared with placebo; however, this was not significant. CONCLUSION: Mepolizumab therapy cannot prevent the eczematous reaction induced by the APT. Furthermore, the influx of tissue eosinophil numbers in the APT is not significantly inhibited after mepolizumab treatment compared with placebo, despite a significant reduction in peripheral blood eosinophils.

Adult↗
PubMed2006

IgE-mediated allergen presentation and blocking antibodies: regulation of T-cell activation in allergy.

It is well established that both the production of IgE by B lymphocytes and the maturation and recruitment of eosinophils in late-phase reactions are dependent on the activation of allergen-specific type-2 T-helper cells. What is less well known is the fact that efficient activation of allergen-specific T cells upon low-dose exposure to allergens is critically dependent on IgE-mediated or -facilitated allergen presentation. In fact, changes in the level of IgE-mediated allergen presentation may account for many of the immunological effects described for specific immunotherapy or anti-IgE treatment. This review aims to summarize the current knowledge, and will discuss the clinical relevance of blocking IgG antibodies induced by specific immunotherapy and anti-IgE monoclonal antibodies that both interfere with IgE-mediated allergen presentation.

Allergens↗
PubMed2006

Characterization of T cell epitopes in alphas1-casein in cow's milk allergic, atopic and non-atopic children.

BACKGROUND: One to two percent of infants suffer from IgE-mediated allergic reactions against cow's milk proteins. Most children develop clinical tolerance, but approximately 15% are still allergic by the age of 10 years. Little is known about the T cell epitopes in individual cow's milk protein in relation to allergy and tolerance. OBJECTIVE: To identify T cell epitopes in alphas1-casein, the most abundant milk protein, and to investigate T cell responses toward these epitopes in allergic, atopic and non-atopic children. METHODS: Allergen-specific T cell lines (TCLs) were derived from peripheral blood mononuclear cells of 11 cow's milk allergic, nine atopic and nine non-atopic children. T cell responses were measured to alphas1-casein and to overlapping peptides (18-mers), spanning the alphas1-casein molecule. Proliferation was determined by incorporation of (3)H-thymidine, and cytokine production (IL-10, IL-13 and IFN-gamma) was measured by ELISA. RESULTS: Four main regions (amino acid (AA) residues 43-66, 73-96, 91-114 and 127-180) in the alphas1-casein molecule were immunogenic to T cells, among which the AA residues 133-156 spanned the immunodominant part. Only subtle differences were found in peptide recognition between the subject groups. Some of the peptides induced slightly Th1- or Th2-skewed cytokine responses. The increased levels of IL-10 in response to alphas1-casein observed in TCLs from atopic children appeared not to be linked to recognition of specific IL-10-inducing epitopes. CONCLUSIONS: The immunodominant sequence in alphas1-casein is spanned by AA residues 133-156. Tolerance towards alphas1-casein in atopic children may be mediated by an overall induction of IL-10 and not by recognition of certain T cell epitopes. The identified T cell epitopes in children with cow's milk allergy may be useful targets in developing peptide immunotherapy.

Adolescent↗
PubMed2006

Modulation of the atopy patch test: tacrolimus 0.1% compared with triamcinolone acetonide 0.1%.

BACKGROUND: The atopy patch test (APT) is an in vivo model to study the induction of eczema by inhalant allergens in atopic dermatitis patients. We studied the effect of pretreatment with topical tacrolimus 0.1% on APT in nonlesional skin of patients with atopic dermatitis. METHODS: Nonlesional skin of the back of patients with atopic dermatitis (n = 8) was treated once daily for 3 weeks with tacrolimus 0.1% ointment. Cetomacrogol ointment (placebo) was used as a negative control and triamcinolone acetonide 0.1% ointment as positive control. Twenty-four hours after the last APT application, samples were taken from the three treated areas (t = 0 and 24 h) for immunohistochemical analysis. RESULTS: Pretreatment with tacrolimus ointment did not suppress nonlesional skin infiltrate, in contrast to triamcinolone acetonide. Furthermore, tacrolimus did not inhibit the induction of the APT macroscopically (t = 24 h). An equal influx of T cells, eosinophils, dendritic cells, CD64+ and Fc epsilon RI-positive cells was present compared with placebo. Only CD36+ and CD68-positive cells were inhibited compared with placebo. All cell types were significantly inhibited in triamcinolone acetonide-treated sites compared with placebo. CONCLUSIONS: Pretreatment with tacrolimus 0.1% ointment does not inhibit the APT reaction in patients with atopic dermatitis.

Adult↗
PubMed2006

Identification of quantitative trait loci for carcass composition and pork quality traits in a commercial finishing cross.

A QTL study for carcass composition and meat quality traits was conducted on finisher pigs of a cross between a synthetic Piétrain/Large White boar line and a commercial sow cross. The mapping population comprised 715 individuals evaluated for a total of 30 traits related to growth and fatness (4 traits), carcass composition (11 traits), and meat quality (15 traits). Offspring of 8 sires (n = 715) were used for linkage analysis and genotyped for 73 microsatellite markers covering 14 chromosomal regions representing approximately 50% of the pig genome. The regions examined were selected based on previous studies suggesting the presence of QTL affecting carcass composition or meat quality traits. Thirty-two QTL exceeding the 5% chromosome-wise significance level were identified. Among these, 5 QTL affecting 5 different traits were significant at the 1% chromosome-wise level. The greatest significance levels were found for a QTL affecting loin weight on SSC11 and a QTL with an effect on the Japanese color scale score of the loin on SSC4. About one-third of the identified QTL were in agreement with QTL previously reported. Results showed that QTL affecting carcass composition and meat quality traits segregated within commercial lines. Use of these results for marker-assisted selection offers opportunities for improving pork quality by within-line selection.

Animals↗
PubMed2005

Purification and immunoglobulin E-binding properties of peanut allergen Ara h 6: evidence for cross-reactivity with Ara h 2.

BACKGROUND: IgE-binding peanut proteins smaller than 15 kDa were previously identified as potential allergens in the majority of our peanut allergic population. OBJECTIVE: To characterize the novel allergen in order to determine whether it was similar to one of the thus far identified recombinant peanut allergens (Ara h 1-7). METHODS: An IgE-binding protein of <15 kDa was purified and identified via N-terminal sequencing. Its IgE-binding properties were investigated using immunoblotting, basophil degranulation, and skin prick testing. Possible cross-reacting epitopes with other peanut allergens were studied using IgE-immunoblotting inhibition. RESULTS: The purified protein is a monomeric protein with a molecular weight of 14,981 Da as determined using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy. The amino acid sequence of the first 39 N-terminal residues is identical to that of Ara h 6, indicating that the allergen is Ara h 6. It is recognized by 20 out of 29 peanut-allergic patients on IgE-immunoblot, and its potent biological functionality is demonstrated by the degranulation of basophils, even at concentrations below 10 pg/mL, and by positive skin prick reactions. Ara h 6 has homology to Ara h 2, especially in the middle part and at the C-terminal part of the protein. Almost complete inhibition of IgE-Ara h 6 interaction with Ara h 2 demonstrates that at least part of the epitopes of Ara h 6 are cross-reactive with epitopes on Ara h 2. CONCLUSIONS: Peanut-derived Ara h 6 is a biologically active allergen recognized by the majority of our peanut-allergic patient population and can be considered a clinically relevant peanut allergen.

2S Albumins, Plant↗
PubMed2005

Identification of strong interleukin-10 inducing lactic acid bacteria which down-regulate T helper type 2 cytokines.

BACKGROUND: Decreased exposure to microbial stimuli has been proposed to be involved in the increased prevalence of atopic disease. Such a relationship was indicated by enhanced presence of typical probiotic bacteria in the intestinal flora correlating with reduced prevalence of atopic disease. Recent clinical trials suggested that probiotic bacteria may decrease and prevent allergic symptoms, but which (different) species or strains may contribute is poorly understood. OBJECTIVE: We sought to select probiotic bacteria by their ability to modulate in vitro production of cytokines by peripheral blood mononuclear cells (PBMCs), to make a rational choice from available strains. METHODS: PBMCs, purified monocytes, and lymphocytes from healthy donors were co-cultured with 13 different strains of probiotic bacteria. The effect of lactic acid bacteria (LAB) on different cell populations and effects on cytokine production induced by the polyclonal T cell stimulator phytohaemagglutinin (PHA) was evaluated by measuring T helper type 1, T helper type 2 (Th2), and regulatory cell cytokines in culture supernatants by multiplex assay. RESULTS: PBMCs cultured with different strains produced large amounts of IL-10 and low levels of IL-12p70, IL-5, and IL-13. In PHA-stimulated PBMC cultures, the tested strains decreased the production of Th2 cytokines. Neutralizing IL-10 production resulted in partial to full restoration of Th2 cytokine production and concurred with an increase in pro-inflammatory cytokines such as IL-12p70 and TNF-alpha. Within the PBMCs, the CD14(+) cell fraction was the main source of IL-10 production upon interaction with LAB. CONCLUSION: Our results indicate that certain strains of lactobacilli and bifidobacteria modulate the production of cytokines by monocytes and lymphocytes, and may divert the immune system in a regulatory or tolerant mode. These specific strains may be favorable to use in prevention or treatment of atopic disease.

Adult↗
PubMed2005

Anti-IL-5 recombinant humanized monoclonal antibody (mepolizumab) for the treatment of atopic dermatitis.

BACKGROUND: Eosinophils may play an important role in the pathogenesis of atopic dermatitis (AD). Interleukin-5 is essential for eosinophil growth, differentiation and migration. A monoclonal antibody to human interleukin-5 (mepolizumab) was developed for atopic diseases. This study was designed to study the effect of mepolizumab in AD. METHODS: Two single doses of 750 mg mepolizumab, given 1 week apart, were studied in patients with moderate to severe AD using a randomized, placebo-controlled parallel group design. The primary endpoint of 'success' to treatment was defined as the percentage of patients with at least 'marked improvement' after 2 weeks as assessed by the Physician's Global Assessment of Improvement (PGA). Furthermore, SCORing AD (SCORAD), pruritus scoring, number of blood eosinophils and serum thymus and activation-regulated chemokine (TARC) values served as secondary endpoints. Fluticasone propionate cream 0.05%, once daily could be used as rescue medication from day 16 if no improvement was recorded. RESULTS: Eighteen patients received mepolizumab and 22 placebo treatment. Peripheral blood eosinophil numbers were significantly reduced in the treatment group compared with placebo (P < 0.05). No clinical success was reached by PGA assessment (P = 0.115), SCORAD (P = 0.293), pruritus scoring and TARC values in the mepolizumab-treated group compared with placebo. However, modest improvement (<50% improvement) assessed by PGA was scored significantly more in the mepolizumab-treated group compared with placebo (P < 0.05). CONCLUSION: Two single doses of 750 mg mepolizumab did not result in clinical success in patients with AD, despite a significant decrease in peripheral blood eosinophils.

Adult↗
PubMed2005

Genetic parameters for carcass composition and pork quality estimated in a commercial production chain.

Breeding goals in pigs are subject to change and are directed much more toward retail carcass yield and meat quality because of the high economic value of these traits. The objective of this study was to estimate genetic parameters of growth, carcass, and meat quality traits. Carcass components included ham and loin weights as primal cuts, which were further dissected into boneless subprimal cuts. Meat quality traits included pH, drip loss, purge, firmness, and color and marbling of both ham and loin. Phenotypic measurements were collected on a commercial crossbred pig population (n = 1,855). Genetic parameters were estimated using REML procedures applied to a bivariate animal model. Heritability estimates for carcass traits varied from 0.29 to 0.51, with 0.39 and 0.51 for the boneless subprimals of ham and loin, respectively. Heritability estimates for meat quality traits ranged from 0.08 to 0.28, with low estimates for the water holding capacity traits and higher values for the color traits: Minolta b*(0.14), L* (0.15), a* (0.24), and Japanese color scale (0.25). Heritability estimates differed for marbling of ham (0.14) and loin (0.31). Neither backfat nor ADG was correlated with loin depth (r(g) = 0.0), and their mutual genetic correlation was 0.27. Loin primal was moderately correlated with ham primal (r(g) = 0.31) and more strongly correlated with boneless ham (r(g) = 0.58). Backfat was negatively correlated with (sub)primal cut values. Average daily gain was unfavorably correlated with subprimals and with most meat quality characteristics measured. Genetic correlations among the color measurements and water-holding capacity traits were high (average r(g) = 0.70), except for Minolta a* (average r(g) = 0.17). The estimated genetic parameters indicate that meat quality and valuable cut yields can be improved by genetic selection. The estimated genetic parameters make it possible to predict the response to selection on performance, carcass, and meat quality traits and to design an effective breeding strategy fitting pricing systems based on retail carcass and quality characteristics.

Adipose Tissue↗
PubMed2004

Relevance of Ara h1, Ara h2 and Ara h3 in peanut-allergic patients, as determined by immunoglobulin E Western blotting, basophil-histamine release and intracutaneous testing: Ara h2 is the most important peanut allergen.

BACKGROUND: A number of allergenic proteins in peanut has been described and the relative importance of these allergens is yet to be determined. OBJECTIVES: We have investigated the relevance of previously identified peanut allergens in well-characterized peanut-allergic patients by in vitro, ex vivo and in vivo assays. METHODS: Thirty-two adult peanut-allergic patients were included based on careful and standardized patient history and the presence of peanut-specific IgE. The diagnosis peanut allergy was confirmed using double-blind placebo-controlled food challenges in 23 patients. Major peanut allergens Ara h1, Ara h2 and Ara h3 were purified from peanuts using ion-exchange chromatography. IgE immunoblotting was performed and IgE-cross-linking capacity was examined by measuring histamine release (HR) after incubating patient basophils as well as passively sensitized basophils with several dilutions of the allergens. Intracutaneous tests (ICTs) using 10-fold dilution steps of the purified allergens and crude peanut extract were performed. RESULTS: Ara h2 was recognized most frequently (26 out of 32) in all tests and induced both positive skin tests and basophil degranulation at low concentrations, whereas Ara h1 and Ara h3 were recognized less frequently and reacted only at 100-fold higher concentrations as analysed with HR and intracutaneous testing (ICT). Next to the three tested allergens, proteins with molecular weights of somewhat smaller than 15 kDa were identified as a IgE-binding proteins on immunoblot in the majority of the patients (20 out of 32). CONCLUSION: We conclude that Ara h2 is, for our patient group, the most important peanut allergen, and that previously unidentified peanut proteins with molecular weights of somewhat smaller than 15 kDa may be important allergens as well. ICT in combination with basophil-HR and IgE immunoblotting provides insight in the patient specificity towards the individual peanut allergens.

2S Albumins, Plant↗
PubMed2004

Efficacy of birch-pollen immunotherapy on cross-reactive food allergy confirmed by skin tests and double-blind food challenges.

BACKGROUND: The effect of birch-pollen immunotherapy (IT) on cross-reactive food allergies is controversial. OBJECTIVE: The aim of this study was to investigate the effect of birch-pollen IT on apple allergy and to evaluate recombinant allergens and double-blind placebo-controlled food challenges (DBPCFCs) as monitoring tools. METHODS: Twenty-five adult birch-pollen- and apple-allergic patients were randomly divided into two groups, either receiving birch-pollen IT or symptomatic drugs only. IgE and IgG4 antibodies against birch pollen, apple, natural Bet v 1 and Mal d 1 were measured. In addition, skin prick tests (SPT) were performed using recombinant Bet v 1 (rBet v 1) and Mal d 1 (rMal d 1). Clinical outcome was evaluated by DBPCFC. CD4(+)CD25(+) regulatory T cells (Tregs) were isolated from peripheral blood and tested in functional assays. RESULTS: Birch-pollen IT resulted in a significant decrease of SPT reactivity for rBet v 1 (30-fold) and rMal d 1 (10-fold) already after 3 months. IgG4 antibodies were potently induced against Bet v 1, displaying cross-reactivity to Mal d 1. Visual analogue scale scores decreased >10-fold in 9/13 patients of the IT group, with three patients converting to negative. In the control group, no decrease was observed. Birch-pollen IT did not lead to detectable changes in the number or function of the CD4(+)CD25(+) Tregs. CONCLUSIONS: This trial supports the claims that birch-pollen IT also decreases allergy to foods containing Bet v 1-homologous allergens. Recombinant allergens and DBPCFCs have proven to be useful tools for monitoring the effect of birch-pollen IT on linked food allergies.

Adult↗
PubMed2004

Atopy patch test in patients with atopic eczema/dermatitis syndrome: comparison of petrolatum and aqueous solution as a vehicle.

BACKGROUND: The atopy patch test (APT) is an in vivo model to study the induction of eczema by inhalant allergens. This study was designed to compare two commonly used APT methods. METHODS: In the first method, the allergen is dissolved in aqueous solution, which is applied on tape-stripped skin. In the second method, the allergen is dissolved in petrolatum and applied without tape stripping. Thirteen patients with atopic dermatitis sensitized to inhalant allergens were patch tested using both methods. Reactions were evaluated macroscopically and microscopically after 48 h. RESULTS: Nine out of 13 patients displayed a positive reaction for both methods. One patient had a positive APT for the aqueous method alone and three for the petrolatum method alone. Reactions were significantly stronger when using the petrolatum method. Histological evaluation of the nine patients positive for both methods showed no significant differences in number of eosinophils, T-cells and neutrophils. CONCLUSION: The APT using the petrolatum vehicle induces a higher number of positive reactions and is significantly stronger relative to the APT using allergen in aqueous vehicle. The cellular influx in both test methods is comparable. Both methods can be used to study the mechanisms in the induction of eczema by inhalant allergens.

Adult↗