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PubMed1999

Peanut oil in vitamin A and D preparations: reactions to skin test and manifestation of symptoms.

The aim of this study was to establish whether there is a link between sensitisation to peanut and exposure to peanut oil in vitamin A and D preparations. Forty-one children with a positive in vivo or in vitro test towards peanut were included. Twenty-one children had consumed vitamins A and D in oil solution, 14 in water solution, and 6 both types. Refined and unrefined peanut oils were obtained and skin prick test extracts were prepared. None of the children exhibited a positive SPT in response to the refined peanut extract. In contrast, 15 children exhibited a positive SPT to the unrefined extract. There was no significant difference in the number of children reacting clinically to peanut exposure who had received vitamins A and D in oil-based or water-based formulations. However, children with clinical allergy to peanut and who had exclusively consumed vitamin A and D in peanut oil, exhibited a greater number of different allergic symptoms upon consumption of peanut compared with clinical allergic children who had consumed the vitamins in water solution or both types (p<0.01). This study indicates that sensitisation to peanut during childhood through consumption of vitamins A and D in oil-based solution seems unlikely, but its consumption may contribute to the development of a wider range of clinical symptoms due to peanut exposure.

Adolescent↗
PubMed2003

Measurement of peptide-specific IgE as an additional tool in identifying patients with clinical reactivity to peanuts.

BACKGROUND: Peanut allergy is one of the most common food allergies, often resulting in severe reactions. Diagnostic decision levels of food-specific IgE antibody concentrations have been described. However, many patients still need to undergo oral peanut challenges because their IgE levels are in the nondiagnostic level. OBJECTIVE: The aim of this study was to determine whether differences exist in IgE-binding epitope recognition between sensitized children with and without symptomatic peanut allergy. METHODS: Eight peptides representing the immunodominant sequential epitopes on Ara h 1, 2, and 3 were synthesized on SPOTs membranes. Individual patient labeling was performed with sera from 15 patients with symptomatic peanut allergy and 16 patients who were sensitized but tolerant. Ten of these 16 patients had "outgrown" their allergy. RESULTS: Regardless of their peanut-specific IgE levels, most patients with symptomatic peanut allergy showed IgE binding to the 3 immunodominant epitopes on Ara h 2. In contrast, each of these epitopes was recognized by < 10% of the tolerant patients. In addition, tolerant patients did not recognize 2 immunodominant epitopes on Ara h 1. At least 93% of symptomatic, but only 12.5% of tolerant patients, recognized 1 of these "predictive" epitopes on Ara h 1 or 2. Moreover, the cumulative IgE binding to the peanut peptides was significantly higher in patients with peanut allergy than in tolerant patients. With up to 50% of patients with peanut-specific IgE levels below diagnostic decision levels still being clinically reactive, oral food challenges could be avoided in ~90% of these patients through determination of peptide-specific IgE. CONCLUSIONS: Determination of epitope recognition provides an additional tool to diagnose symptomatic peanut allergy, especially in children with peanut-specific IgE below diagnostic decision levels.

2S Albumins, Plant↗
PubMed2005

Beyond allergen avoidance: update on developing therapies for peanut allergy.

PURPOSE OF REVIEW: Food allergy has emerged as a significant health problem. Peanut allergy is a major cause of food-induced fatal and near fatal anaphylactic reactions, and the incidence in children is increasing. Attempts to manage peanut allergy by strict avoidance are often unsuccessful. The purpose of this review is to highlight the most promising novel approaches for treating peanut allergy beyond allergen avoidance. RECENT FINDINGS: In the past 5 years much effort has been devoted to developing a treatment for peanut allergy. A recent clinical trial showed that monthly injections of humanized recombinant anti-IgE antibodies increased the threshold for allergic responses of peanut-sensitive individuals, at least to small amounts of peanut protein. However, this treatment cannot cure peanut allergy, and continuous monthly injections are necessary to maintain protection. Developing new therapies for the treatment of peanut allergy is essential. In reviewing publications between 2003 and 2005, several novel therapeutic approaches, tested in the murine model of peanut anaphylaxis appeared promising. Immunotherapy with engineered recombinant peanut protein and bacterial adjuvant significantly protected peanut allergic mice from anaphylaxis. It was also found that a Chinese herbal medicine formula called Food Allergy Herbal Formula-2 completely blocked anaphylaxis up to 5 weeks following therapy. These potent therapeutic effects are associated with immunoregulation of Th1 and Th2 responses. SUMMARY: Although there is no effective and safe therapy for food allergy, many novel approaches are under investigation. Some of these approaches may provide allergists with effective treatments in the near future.

2S Albumins, Plant↗
PubMed2006

Quantification of Ara h 1 in peanuts: why roasting makes a difference.

BACKGROUND: Increased allergenicity of roasted vs. raw peanut has been reported by showing higher IgE binding to roasted peanut extracts. OBJECTIVE: To study the effect of roasting on Ara h 1 quantification in peanut using a specific monoclonal antibody-based ELISA, and to compare the Ara h 1 content from different kernel size peanuts from four runner cultivars. METHODS: Raw or oven-roasted (177 degrees C for 5-30 min) runner peanuts were crushed and extracted at 60 degrees C. Inhibition ELISA was used to study binding of Ara h 1 purified from raw or roasted peanut. Runner peanuts of four different cultivars were collected, shelled, sized and roasted for 15 min at 177 degrees C. Ara h 1 in the extracts was compared by ELISA. RESULTS: Ara h 1 levels were up to 22-fold higher in roasted than in raw peanuts (820 vs. 37 microg/mL, in a representative experiment) with an Ara h 1 peak at 10-15 min of roasting. Inhibition ELISA indicated that this increase was not due to conformational changes in the Ara h 1 monoclonal antibody epitopes. Ara h 1 was found at lower levels in number 1 than in jumbo- and medium-sized peanuts, and no differences were found among cultivars. CONCLUSION: These results suggest that roasting increases the efficiency of Ara h 1 extraction, and/or that the monoclonal antibody binding epitopes were more accessible in roasted peanut. Expression of Ara h 1 is associated with peanut maturity.

Allergens↗
PubMed2001

Detection of peanut allergens in breast milk of lactating women.

CONTEXT: Most individuals who react to peanuts do so on their first known exposure. A potential but unproven route of occult exposure resulting in sensitization to peanut is via breast milk during lactation. OBJECTIVE: To investigate the ability of maternal dietary peanut protein to pass into breast milk during lactation. DESIGN AND SETTING: Clinical investigation conducted at 2 North American hospitals from March 1999 to October 2000. PATIENTS: Twenty-three healthy, lactating women aged 21 to 35 years. INTERVENTION: Each woman consumed 50 g of dry roasted peanuts, after which breast milk samples were collected at hourly intervals. MAIN OUTCOME MEASURES: Presence in breast milk of total peanut protein, analyzed by a sandwich enzyme-linked immunosorbent assay, and 2 major peanut allergens, Ara h 1 and Ara h 2, detected by immunoblot analysis. RESULTS: Peanut protein was detected in 11 of 23 subjects. It was detected in 10 subjects within 2 hours of ingestion and in 1 subject within 6 hours. The median peak peanut protein concentration in breast milk was 200 ng/mL (mean, 222 ng/mL; range, 120-430 ng/mL). Both major peanut allergens Ara h 1 and Ara h 2 were detected. CONCLUSIONS: Peanut protein is secreted into breast milk of lactating women following maternal dietary ingestion. Exposure to peanut protein during breastfeeding is a route of occult exposure that may result in sensitization of at-risk infants.

2S Albumins, Plant↗
PubMed1983

Multiplicity of allergens in peanuts.

Crude peanut protein fractions from raw and roasted peanuts were examined in the RAST with 10 sera from patients showing clinical peanut sensitivity. The radioactive uptake results, which were generally high, did not reveal any distinguishable pattern. Two commercially available peanut proteins, peanut lectin and phospholipase D, gave poor RAST responses. Three purified peanut proteins, alpha-arachin, conarachin I, and concanavalin A-reactive glycoprotein, all gave significant RAST results that were generally lower than those obtained with the crude extracts. The extent of RAST inhibition obtained with these materials was inversely related to their abundance in the total peanut protein. Crossed immunoelectrophoresis with extracts from raw and roasted peanut indicated the presence of 22 and 10 anodically migrating antigens, respectively. Sixteen IgE binding antigens were revealed for raw peanut and seven for roasted peanut after incubation with a mixed serum from the 10 patients in crossed radioimmunoelectrophoresis (CRIE) using 125I-labeled anti-IgE. CRIE plates treated with individual serum samples showed that all the patients had specific IgE for the major antigen peak, which has been tentatively identified as alpha-arachin. This major storage protein of peanut, which is known to be particularly heat resistant; may be of greater clinical significance than its apparently low RAST activity would seem to indicate.

Adolescent↗
PubMed1989

The natural history of peanut allergy.

Between 1973 and 1985, 114 children, aged 2 to 14 years, underwent double-blind, placebo-controlled, food challenge (DBPCFC) to peanut. Thirty-two of 46 children with symptoms produced by DBPCFC to peanut were included in this longitudinal evaluation. Contact was made with the 32 subjects 2 to 14 years after their positive DBPCFC to peanut. All 32 subjects had exhibited a positive puncture skin test to peanut at the time of the original evaluation. Sixteen subjects had experienced symptoms caused by accidental peanut ingestion in the year before contact. Eight subjects had reacted to accidental ingestion in more than 1 year but less than 5 years before contact. Eight subjects had completely avoided peanut since the original evaluation and positive DBPCFC. No subjects could be demonstrated to have "outgrown" their peanut reactivity. All subjects tested continued to have skin reactivity to a puncture skin test with peanut extract. It appears uncommon for peanut-sensitive patients to lose their clinical reactivity, even after many years have elapsed. In addition, data were collected concerning reactions to other legumes and other (nonlegume) nuts. Only two patients with DBPCFC to peanut reacted on DBPCFC to soy or pea (one each). None of the subjects with a positive DBPCFC to peanut reacted to nonlegume nuts.

Adolescent↗
PubMed2001

Association of end-product adducts with increased IgE binding of roasted peanuts.

Recently, we have shown that roasted peanuts have a higher level of IgE binding (i.e., potentially more allergenic) than raw peanuts. We hypothesized that this increase in IgE binding of roasted peanuts is due to an increased levels of protein-bound end products or adducts such as advanced glycation end products (AGE), N-(carboxymethyl)lysine (CML), malondialdehyde (MDA), and 4-hydroxynonenal (HNE). To support our hypothesis, we produced polyclonal antibodies (IgG) to each of these adducts, determined their levels in raw and roasted peanuts, and examined their ability to bind to IgE from a pooled serum of patients with clinically important peanut allergy. Results showed that AGE, CML, MDA, and HNE adducts were all present in raw and roasted peanuts. Roasted peanuts exhibited a higher level of AGE and MDA adducts than raw peanuts. IgE was partially inhibited in a competitive ELISA by antibodies to AGE but not by antibodies to CML, MDA, or HNE. This indicates that IgE has an affinity for peanut AGE adducts. Roasted peanuts exhibited a higher level of IgE binding, which was correlated with a higher level of AGE adducts. We concluded that there is an association between AGE adducts and increased IgE binding (i.e., allergenicity) of roasted peanuts.

Allergens↗
PubMed2000

The effects of roasting on the allergenic properties of peanut proteins.

BACKGROUND: Because of the widespread use of peanut products, peanut allergenicity is a major health concern in the United States. The effect or effects of thermal processing (roasting) on the allergenic properties of peanut proteins have rarely been addressed. OBJECTIVE: We sought to assess the biochemical effects of roasting on the allergenic properties of peanut proteins. METHODS: Competitive inhibition ELISA was used to compare the IgE-binding properties of roasted and raw peanut extracts. A well-characterized in vitro model was used to test whether the Maillard reaction contributes to the allergenic properties of peanut proteins. The allergic properties were measured by using ELISA, digestion by gastric secretions, and stability of the proteins to heat and degradation. RESULTS: Here we report that roasted peanuts from two different sources bound IgE from patients with peanut allergy at approximately 90-fold higher levels than the raw peanuts from the same peanut cultivars. The purified major allergens Ara h 1 and Ara h 2 were subjected to the Maillard reaction in vitro and compared with corresponding unreacted samples for allergenic properties. Ara h 1 and Ara h 2 bound higher levels of IgE and were more resistant to heat and digestion by gastrointestinal enzymes once they had undergone the Maillard reaction. CONCLUSIONS: The data presented here indicate that thermal processing may play an important role in enhancing the allergenic properties of peanuts and that the protein modifications made by the Maillard reaction contribute to this effect.

Allergens↗
PubMed2001

The natural history of peanut allergy.

BACKGROUND: It has traditionally been assumed that peanut allergy is rarely outgrown. OBJECTIVE: The goal of this study was to determine the number of children with peanut allergy who become tolerant of peanut. METHODS: Patients aged 4 to 20 years with a diagnosis of peanut allergy were evaluated by questionnaire, skin testing, and a quantitative antibody fluorescent-enzyme immunoassay. Patients who had been reaction free in the past year and had a peanut IgE (PN-IgE) level less than 20 kilounits of antibody per liter (kU(A)/L) were offered an open or double-blind, placebo-controlled peanut challenge. RESULTS: A total of 223 patients were evaluated, and of those, 85 (PN-IgE < 0.35-20.4 kU(A)/L [median 1.42 kU(A)/L]) participated in an oral peanut challenge. Forty-eight (21.5%) patients had negative challenge results and were believed to have outgrown their peanut allergy (aged 4-17.5 years [median 6 years]; PN-IgE < 0.35-20.4 kU(A)/L [median 0.69 kU(A)/L]). Thirty-seven failed the challenge (aged 4-13 years [median 6.5 years]; RAST < 0.35-18.2 kU(A)/L [median 2.06 kU(A)/L]). Forty-one patients with PN-IgE levels less than 20 kU(A)/L declined to undergo challenge, and 97 were not eligible for challenge because their PN-IgE levels were greater than 20 kU(A)/L or they had had a recent reaction. Sixty-seven percent of patients with PN-IgE levels less than 2 kU(A)/L and 61% with levels less than 5 kU(A)/L had negative challenge results. Of those who underwent challenge, PN-IgE levels for those who passed versus those who failed were different at the time of challenge (P = .009), but not at the time of diagnosis (P = .25). CONCLUSION: This study demonstrates that peanut allergy is outgrown in about 21.5% of patients. Patients with low PN-IgE levels should be offered a peanut challenge in a medical setting to demonstrate whether they can now tolerate peanuts.

Adolescent↗
PubMed2004

Improved diet quality with peanut consumption.

OBJECTIVE: To evaluate the diet quality of free-living men, women, and children choosing peanuts and peanut products. DESIGN: Using data reported in the Continuing Survey of Food Intake by Individuals and Diet and Health Knowledge Survey (CSFII/DHKS) from 1994-1996, food codes were used to sort respondents by use or nonuse of peanuts. SUBJECTS: A nationally representative sample of 4,751 men, 4,572 women, and 4,939 children (boys and girls, 2-19 yrs) who completed 2-day intake records. MEASURES OF OUTCOME: The two-sample t test was used to analyze differences between peanut users and nonusers for energy, nutrient intakes, Health Eating Index (HEI) scores, and body mass index (BMI). RESULTS: Peanut users (24% of CSFII/DHKS) had higher intakes (p < 0.001) of protein, total fat, polyunsaturated fat (PUFA), monounsaturated fat, (MUFA) (p < 0.01), fiber, vitamin A, vitamin E, folate, calcium, magnesium, zinc, and iron. Percent of energy from saturated fat was not significantly different for men, women or girls and was slightly lower (p < 0.01) for boys. Dietary cholesterol of peanut users was lower for all population groups; this decrease was significant for both men (p < 0.01) and children (p < 0.001). The HEI was calculated as a measure of overall nutrient profile of the diets and was significantly greater for peanut users (men 61.4, women, 65.1, children 66.8) compared to nonusers (men 59.9, women 64.1, children 64.7) for men (p = 0.0074) and children (p < 0.001). Energy intake was significantly higher in all population groups of peanut users (p < 0.001; boys: p < 0.01); however mean BMI for peanut users was lower for all gender/age categories (women: p < 0.05; children: p < 0.001). CONCLUSIONS: These results demonstrate improved diet quality of peanut users, indicated by the higher intake of the micronutrients vitamin A, vitamin E, folate, calcium, magnesium, zinc, and iron and dietary fiber, and by the lower intake of saturated fat and cholesterol. Despite a higher energy intake over a two-day period, peanut consumption was not associated with a higher BMI.

Adolescent↗
PubMed2004

Nutritional value and acceptability of homemade maize/sorghum-based weaning mixtures supplemented with rojo bean flour, ground sardines and peanut paste.

Low nutrient density in weaning foods is the major cause of under-nutrition among infants and young children in developing countries. Ten types of composite weaning diets (namely, maize-rojo beans-peanut, maize-peanut-sardines, maize-peanut-sardine-rojo beans, maize-peanut-soaked rojo beans, maize-peanut-germinated rojo beans, sorghum-rojo beans-peanut, sorghum-peanut-sardines, sorghum-peanut-sardine-rojo beans, sorghum-peanut-soaked rojo beans, and sorghum-peanut-germinated rojo beans) were formulated and assayed for proximate composition, energy, mineral density, tannin content and residual urease activity. The diets were also evaluated for storage stability under ambient conditions, sensory quality and overall acceptability. Results of the study indicated that, concentrations of protein, fat, ash, calcium, iron, zinc and copper were significantly (P<0.05) increased when plain maize and sorghum gruels were enriched with rojo beans, peanut paste and/or ground sardines. Soaking and germinating the rojo beans and dehulling the sorghum reduced the concentration of tannins in the gruels significantly (P<0.05). Residual urease activity ranged between 0.00 and 0.07 units, about 10-fold lower than the maximum level (0.8 units) allowed in weaning foods. Both maize and sorghum-based composite gruels had a short shelf-life under ambient conditions (26.4 degrees C) ranging between 4 and 6 h, with gruels containing ground sardines showing a tendency to spoil faster. All composite gruels except those containing germinated rojo beans were highly liked and accepted by consumers (P<0.05), similar to the plain maize and sorghum gruels. The maize and sorghum-based composite products therefore have a potential for use as weaning and/or supplementary foods for older infants and young children. Further investigations are suggested to extend the shelf-life of the composite products and improve the organoleptic quality of the diets containing germinated rojo beans.

Adult↗
PubMed2006

Storage protein profiles in Spanish and runner market type peanuts and potential markers.

BACKGROUND: Proteomic analysis has proven to be the most powerful method for describing plant species and lines, and for identification of proteins in complex mixtures. The strength of this method resides in high resolving power of two-dimensional electrophoresis (2-DE), coupled with highly sensitive mass spectrometry (MS), and sequence homology search. By using this method, we might find polymorphic markers to differentiate peanut subspecies. RESULTS: Total proteins extracted from seeds of 12 different genotypes of cultivated peanut (Arachis hypogaea L.), comprised of runner market (A. hypogaea ssp. hypogaea) and Spanish-bunch market type (A. hypogaea ssp. fastigiata), were separated by electrophoresis on both one- and two-dimensional SDS-PAGE gels. The protein profiles were similar on one-dimensional gels for all tested peanut genotypes. However, peanut genotype A13 lacked one major band with a molecular weight of about 35 kDa. There was one minor band with a molecular weight of 27 kDa that was present in all runner peanut genotypes and the Spanish-derivatives (GT-YY7, GT-YY20, and GT-YY79). The Spanish-derivatives have a runner-type peanut in their pedigrees. The 35 kDa protein in A13 and the 27 kDa protein in runner-type peanut genotypes were confirmed on the 2-D SDS-PAGE gels. Among more than 150 main protein spots on the 2-D gels, four protein spots that were individually marked as spots 1-4 showed polymorphic patterns between runner-type and Spanish-bunch peanuts. Spot 1 (ca. 22.5 kDa, pI 3.9) and spot 2 (ca. 23.5 kDa, pI 5.7) were observed in all Spanish-bunch genotypes, but were not found in runner types. In contrast, spot 3 (ca. 23 kDa, pI 6.6) and spot 4 (ca. 22 kDa, pI 6.8) were present in all runner peanut genotypes but not in Spanish-bunch genotypes. These four protein spots were sequenced. Based on the internal and N-terminal amino acid sequences, these proteins are isoforms (iso-Ara h3) of each other, are iso-allergens and may be modified by post-translational cleavage. CONCLUSION: These results suggest that there may be an association between these polymorphic storage protein isoforms and peanut subspecies fastigiata (Spanish type) and hypogaea (runner type). The polymorphic protein peptides distinguished by 2-D PAGE could be used as markers for identification of runner and Spanish peanuts.

Amino Acid Sequence↗
PubMed1986

Influence of dietary crude protein on peanut skin digestibility and utilization by feedlot steers.

Peanut skins were fed at 15% of steer diets in metabolism and feedlot trials. Elevation of dietary protein using soybean meal or soybean meal plus urea and ammoniation of skins were evaluated as methods of overcoming detrimental performance and digestibility effects of tannins in peanut skins. Digestibility of dry matter, crude protein and energy were not different (P greater than .05) for steers fed a control diet with 11.4% crude protein with no skins compared with high-protein 15% peanut skin diets with soybean meal (15.5% crude protein) or soybean meal plus urea (16% crude protein). Dry matter, crude protein and energy digestibilities of control and of high-protein peanut skin diets were higher (P less than .05) compared with an 11.4% crude protein peanut skin diet and a 12.2% crude protein diet with ammoniated peanut skins. Ether extract digestibility was higher (P less than .05) for all peanut skin diets compared with the control. Nitrogen retention (g/d) was not different (P greater than .05) for control and high-protein peanut skin diets, and nitrogen retention on these diets was higher (P less than .05) compared with the lower protein and ammoniated peanut skin diets. Diets fed in the metabolism trial, except for the ammoniated peanut skin diet, were fed to 96 steers (345 kg initial wt) in a 109-d feedlot trial. Performance was lower (P less than .05) for steers fed the lower-protein peanut skin diet compared with other treatments through d 56; this diet was discontinued as a treatment on d 62.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed2006

Determination of no-observed-adverse-effect levels and eliciting doses in a representative group of peanut-sensitized children.

BACKGROUND: Current labeling practices for allergenic foods like peanut can be inadequate. For future regulatory and industry guidelines, information on no-observed-adverse-effect levels (NOAELs) and eliciting doses (EDs) for allergenic foods is necessary. OBJECTIVE: To determine NOAEL and ED in a representative group of peanut-sensitized children, relate these data to history and sensitization, and evaluate the outcome of dietary management. METHODS: From an overall eligible group of 96 peanut-sensitized children, a representative group of 27 was evaluated by questionnaires, skin prick test, determination of specific IgE, and double-blind placebo-controlled food challenge (DBPCFC) with peanut according to the international consensus protocol, with 9 doses ranging from 10 microg to 3 g peanut flour. Dietary management was evaluated over a 12-month period. RESULTS: Twenty-two children (81%) had a positive DBPCFC. The NOAEL in this group was 1 mg peanut flour, corresponding to 2 mg whole peanut. The ED for subjective symptoms (10 mg to 3 g) was significantly lower than for objective symptoms (100 mg to 3 g; P = .002). Severe reactions occurred only at high doses. EDs were not correlated to previous reactions by history, skin prick test, or specific IgE levels. All patients with a positive DBPCFC were advised to follow a strict diet. During the follow-up period, 10 patients had a less strict diet likely containing traces of peanut. In 3 cases, a mild reaction occurred with food products labeled "may contain peanut." CONCLUSION: The NOAEL in a representative group of children with peanut allergy was 2 mg. Dietary compliance in half of this group was inadequate.

Adolescent↗
PubMed2006

Peanut allergen exposure through saliva: assessment and interventions to reduce exposure.

BACKGROUND: Exposure to food allergens through saliva (kissing, utensils) can cause local and systemic allergic reactions. OBJECTIVE: To determine the time course of peanut allergen (Ara h 1) persistence in saliva after ingestion of peanut butter and to evaluate mouth cleansing interventions to reduce salivary peanut allergen. METHODS: Thirty-eight individuals ingested 2 tablespoons of peanut butter, and saliva was collected at various time points. At another time, samples were collected after 5 interventions (brushing teeth, brushing and rinsing, rinsing, waiting then brushing, waiting then chewing gum). Detection of Ara h 1 was performed by a monoclonal-based ELISA (detection limit, 15-20 ng/mL). RESULTS: Salivary Ara h 1 varied considerably immediately after ingestion, but included levels expected to invoke reactions (as much as 40 microg/mL). Most (87%) subjects with detectable peanut after a meal had undetectable levels by 1 hour with no interventions. None had detectable levels several hours later after a peanut-free lunch. This result indicates (95% confidence) that 90% would have undetectable Ara h 1 in saliva under these circumstances. All of the interventions reduced salivary Ara h 1, in some cases by >95%, but Ara h 1 remained detectable in approximately 40% of samples (though typically below thresholds reported to induce reactions). CONCLUSION: Patients with peanut allergy require counseling regarding risks of kissing or sharing utensils, even if partners have brushed teeth or chewed gum. Advice to reduce risks, though not as ideal as total avoidance, includes waiting a few hours plus eating a peanut-free meal. CLINICAL IMPLICATIONS: Waiting several hours and ingesting a peanut-free meal were more effective at reducing salivary peanut protein concentration than simple, immediate interventions.

Adolescent↗
PubMed2006

IgE cross-reactivity between the major peanut allergen Ara h 2 and tree nut allergens.

Allergy to peanut and tree nuts is characterised by a high frequency of life-threatening anaphylactic reactions and typically lifelong persistence. Although peanut is the most common cause of nut allergy, peanut allergic patients are frequently also sensitive to tree nuts. It is not known if this is due to cross-reactivity between peanut and tree nut allergens. In this study, the major peanut allergen Ara h 2 was cloned from peanut cDNA, expressed in E. coli cells as a His-tag fusion protein and purified using a Ni-NTA column. Immunoblotting, ELISA and basophil activation indicated by CD63 expression all confirmed the IgE reactivity and biological activity of rAra h 2. To determine whether or not this allergen plays a role in IgE cross-reactivity between peanut and tree nuts, inhibition ELISA was performed. Pre-incubation of serum from peanut allergic patients with increasing concentrations of almond or Brazil nut extract inhibited IgE binding to rAra h 2. Purified rAra h 2-specific serum IgE antibodies also bound to proteins present in almond and Brazil nut extracts by immunoblotting. This indicates that the major peanut allergen, Ara h 2, shares common IgE-binding epitopes with almond and Brazil nut allergens, which may contribute to the high incidence of tree nut sensitisation in peanut allergic individuals.

2S Albumins, Plant↗
PubMed2003

RBL cells expressing human Fc epsilon RI are a sensitive tool for exploring functional IgE-allergen interactions: studies with sera from peanut-sensitive patients.

Rat basophilic leukemia cells (RBL SX-38) express the alpha, beta, and gamma chains of human Fc epsilon RI. Following sensitization with IgE from a subset of allergic human donors, these cells can be triggered by exposure to anti-IgE or to very low concentrations of specific allergens. We examined 18 sera from patients who were highly sensitive to peanuts by history and had anti-peanut IgE by in vitro testing. The ability of these sera to sensitize the RBL SX-38 cells for degranulation with peanut allergens correlates very well with the absolute amount of anti-peanut IgE (r=0.95; p<0.001). The most effective sera contained at least 50 kU/l of total IgE and at least 15 kU/l of peanut-specific IgE. RBL SX-38 cells sensitized with these sera degranulated optimally upon exposure to anti-IgE (net degranulation of 40+/-8%, means+/-S.D.; n=8) and to a 10(5)-10(6) dilution of crude peanut extract (CPE) (37+/-7% net degranulation; 93+/-13% of that seen with anti-IgE). This assay is quite sensitive. Cells sensitized with selected sera are activated by exposure to a 1:10(7) dilution of the CPE containing picogram amounts of peanut allergens. This assay is also quite specific. Cells sensitized with sera from patients with anti-peanut IgE and no detectable IgE against soybean, walnut or grass pollen did not degranulate following exposure to these latter antigens. The converse was also true; cells sensitized with sera from patients without anti-peanut IgE did not react to peanut. These data demonstrate that RBL cells expressing human Fc epsilon RI form the basis of a useful model system for the detection of allergens and for the study of IgE-allergen interactions.

Adult↗