Coconut allergy: Characteristics of reactions and diagnostic predictors in a pediatric tertiary care center.

BACKGROUND: Little is known on the clinical manifestations of coconut allergy. Our knowledge to date is mainly based on case reports. OBJECTIVE: To characterize the allergic reactions to coconut and suggest diagnostic cutoffs for specific immunoglobulin E (sIgE) and skin prick testing (SPT) to predict clinically reactive coconut allergy. METHODS: Methods include retrospective chart review at an urban tertiary care center of patients with positive testing result for coconut. Probability curves were computed by logistic regression for SPT and coconut sIgE. RESULTS: Of 275 records reviewed, 69 patients reported coconut reactions and 206 were sensitized only or nonallergic. The reactions occurred with breastfeeding (n = 2), contact (n = 10), or oral ingestion (n = 57). Approximately 50% of oral ingestion reactions were associated with mild/moderate anaphylaxis. Clinical reactivity vs sensitization was more common in topical coconut users (2-fold) (P = .02). Although not statistically significant, there was a trend toward more coconut allergy vs sensitization in Asian and African American patients. The probability of allergy with positive SPT result was approximately 50% and with sIgE was approximately 60%. At an SPT of 9 mm wheal or sIgE of 58 kU of allergen/L, there is a 95% probability of reaction. Cosensitization with tree nuts, legumes, and seeds was common. Macadamia nut had the strongest correlation with coconut (r = 0.81, P < .001, n = 101). CONCLUSION: Although the rate of reactivity to coconut in sensitized individuals is low, half of the reactions from consumption met the criteria for anaphylaxis. Clinicians should be aware of the spectrum of reactions and diagnostic use of sIgE and SPT.

Cloning, expression and immunological characterisation of Coc n 1, the first major allergen from Coconut pollen.

Coconut pollen has been documented to be a major contributor to the aeroallergen load in India, causing respiratory allergy in a large cohort of susceptible individuals. Here, we report the identification of the first major allergen from Coconut pollen, Coc n 1. The full-length sequence of the allergen was determined from previously identified peptides and overexpressed in E. coli. Recombinant Coc n 1 folded into a trimer and was found to possess allergenicity equivalent to its natural counterpart. Proteolytic processing of Coc n 1 led to the formation of an immunodominant ∼20 kDa C-terminal subunit and the site of cleavage was determined by amino acid microsequencing. Five linear IgE binding epitopes were predicted and mapped on the homology modelled structure of Coc n 1. Amongst three immunodominant epitopes, two were present towards the C-terminal end. Coc n 1 was found to belong to the highly diverse cupin superfamily and mimics its structure with known 7S globulin or vicilin allergens but lacks sequence similarity. Using sequence similarity networks, Coc n 1 clustered as a separate group containing unannotated cupin domain proteins and did not include known vicilin allergens except Gly m Bd 28 kDa, a Soybean major allergen. 7S globulins are major storage proteins and food allergens, but presence of such protein in pollen grains is reported for the first time. Further study on Coc n 1 may provide insights into its function in pollen grains and also in the development of immunotherapy to Coconut pollen allergy.

Immunological detection of the Weligama coconut leaf wilt disease associated phytoplasma: Development and validation of a polyclonal antibody based indirect ELISA.

Weligama coconut leaf wilt disease (WCLWD) causes heavy losses in the coconut cultivations of southern Sri Lanka. The in-house developed and validated indirect ELISA was based on specific polyclonal antibodies raised in female New Zealand White rabbits, against partially purified WCLWD associated phytoplasma. This ELISA has the potential to distinguish secA PCR confirmed, WCLWD associated phytoplasma positive palms from phytoplasma free palms at high accuracy (93%) and sensitivity (92.7%), but with marginal specificity (79%). The calculated ELISA cross reactivity index (CRI) values were low for sugarcane white leaf (7%) and sugarcane grassy shoot (8%) infected leaves, but with marked highCRIfor both Bermuda grass white leaf (69%) and areca nut yellow leaf (70%) infected leaves. SecA gene based phylogenetic relationships of the WCLWD associated phytoplasma with these other locally prevalent phytoplasma strains elucidated this immunological cross reactivity, which was further reiterated by virtual restriction fragment length polymorphism analysis. Based on scanning electron microscopy, this study provides additional visual evidence, for the presence of phytoplasmas in WCLWD infected tissues.

Immune reactivity against a variety of mammalian milks and plant-based milk substitutes.

The research reported here seeks to evaluate the allergenicity and antigenicity of different mammalian and plant-based milks/milk substitutes in healthy subjects. We used ELISA to measure IgE and IgG antibodies against cow, goat, sheep, camel, human milks, and soy, almond, and coconut plant-based milk substitutes, as well as IgA antibodies against all these apart from human milk, in 500 individuals in order to find the percentage of antibody elevation. IgG and IgE positivity showed that human milk was the least antigenic and allergenic, followed by camel milk. Cow's milk showed the highest percentage of elevation or reactivity. Among plant-based milk substitutes, the almond-based substitute was the most allergenic with the highest IgE reactivity, while the coconut milk substitute was lowest. For IgG and IgA immuno-reactivity, soy was first, with coconut again the lowest. We found IgE and IgG immune reactivity against coconut, almond and soymilks in some individuals who were non-reactive to mammalian milk, therefore, we should not assume that consumption of these milks is automatically without risk of allergenic response. We selected 24 samples out of the original 500 for the measurement of IgE antibodies against five different types of cow's milk, from non-organic to organic, A1 and A2. Statistical variance analysis detected no significant difference in IgE, IgG and IgA immune reactivities of the five different cow milks. Our results showed that if an individual is immuno-reactive to cow's milk, organic or not, the probability of reacting to goat and sheep milk is very high. Overall, the results presented here showed that for individuals allergic to cow's milk, the least allergenic alternatives in descending order are human, camel, sheep, and goat milks. Before choosing an alternative for cow's milk, one must go through accurate and quantitative blood testing for determination of IgE, IgG and IgA antibodies against different mammalian and plant-based milks/milk substitutes.

Crystal structure determination and analysis of 11S coconut allergen: Cocosin.

Allergy is an abnormal immune response against an innocuous target. Food allergy is an adverse reaction caused by common foods most well-known being those involving peanuts. Apart from mono sensitized food allergy, cross-reactivity with other food allergens is also commonly observed. To understand the phenomenon of cross-reactivity related to immune response, three dimensional structures of the allergens and their antigenic epitopes has to be analysed in detail. The X-ray crystal structure of Cocosin, a common 11S food allergen from coconut, has been determined at 2.2Å resolution using molecular replacement technique. The monomer of 52kDa is composed of two ß-jelly roll domains, one with acidic and the other with basic character. The structure shows hexameric association with two trimers facing each other. Though the overall structure of Cocosin is similar to other 11S allergens, the occurrence of experimentally determined epitopes of the peanut allergen Ara h 3 at flexible as well as variable regions could be the reason for the clinically reported result of cross-reactivity that the peanut allergic patients are not sensitized with coconut allergen.

Crystal Structure of Cocosin, A Potential Food Allergen from Coconut (Cocos nucifera).

Coconut (Cocos nucifera) is an important palm tree. Coconut fruit is widely consumed. The most abundant storage protein in coconut fruit is cocosin (a likely food allergen), which belongs to the 11S globulin family. Cocosin was crystallized near a century ago, but its structure remains unknown. By optimizing crystallization conditions and cryoprotectant solutions, we were able to obtain cocosin crystals that diffracted to 1.85 Å. The cocosin gene was cloned from genomic DNA isolated from dry coconut tissue. The protein sequence deduced from the predicted cocosin coding sequence was used to guide model building and structure refinement. The structure of cocosin was determined for the first time, and it revealed a typical 11S globulin feature of a double layer doughnut-shaped hexamer.

Charting novel allergens from date palm pollen (Phoenix sylvestris) using homology driven proteomics.

Pollen grains from Phoenix sylvestris (date palm), a commonly cultivated tree in India has been found to cause severe allergic diseases in an increasing percentage of hypersensitive individuals. To unearth its allergenic components, pollen protein were profiled by two-dimensional gel electrophoresis followed by immunoblotting with date palm pollen sensitive patient sera. Allergens were identified by MALDI-TOF/TOF employing a layered proteomic approach combining conventional database dependent search and manual de novo sequencing followed by homology-based search as Phoenix sylvestris is unsequenced. Derivatization of tryptic peptides by acetylation has been demonstrated to differentiate the 'b' from the 'y' ions facilitating efficient de novo sequencing. Ten allergenic proteins were identified, out of which six showed homology with known allergens while others were reported for the first time. Amongst these, isoflavone reductase, beta-conglycinin, S-adenosyl methionine synthase, 1, 4 glucan synthase and beta-galactosidase were commonly reported as allergens from coconut pollen and presumably responsible for cross-reactivity. One of the allergens had IgE binding epitope recognized by its glycan moiety. The allergenic potency of date palm pollen has been demonstrated using in vitro tests. The identified allergens can be used to develop vaccines for immunotherapy against date palm pollen allergy. THE SIGNIFICANCE OF THE STUDY: Identification of allergenic proteins from sources harboring them is essential in developing therapeutic interventions. This is the first comprehensive study on the identification of allergens from Phoenix sylvestris (date palm) pollen, one of the major aeroallergens in India using a proteomic approach. Proteomic methods are being increasingly used to identify allergens. However, since many of these proteins arise from species which are un-sequenced, it becomes difficult to interpret those using conventional proteomics. Date palm being an unsequenced species, the IgE-reactive proteins have been identified using a stratified proteomic workflow incorporating manual de novo sequencing and homology-based proteomics. This study also gives an insight into the presence of glycan nature of the IgE binding epitopes. Five proteins have been found to be common with coconut pollen allergens and presumably responsible for cross-reactivity. These can be used in diagnostics to differentiate patient cohorts allergic to both coconut and date palm pollen from true date palm pollen allergic subjects. This would also determine better specific immunotherapy regimes between the two cohorts. The allergens identified herein have potential towards vaccine development in date palm pollen allergy as well as in enriching the existing catalogue of allergenic proteins.

Association of tree nut and coconut sensitizations.

BACKGROUND: Coconut (Cocos nucifera), despite being a drupe, was added to the US Food and Drug Administration list of tree nuts in 2006, causing potential confusion regarding the prevalence of coconut allergy among tree nut allergic patients. OBJECTIVE: To determine whether sensitization to tree nuts is associated with increased odds of coconut sensitization. METHODS: A single-center retrospective analysis of serum specific IgE levels to coconut, tree nuts (almond, Brazil nut, cashew, chestnut, hazelnut, macadamia, pecan, pistachio, and walnut), and controls (milk and peanut) was performed using deidentified data from January 2000 to August 2012. Spearman correlation (ρ) between coconut and each tree nut was determined, followed by hierarchical clustering. Sensitization was defined as a nut specific IgE level of 0.35 kU/L or higher. Unadjusted and adjusted associations between coconut and tree nut sensitization were tested by logistic regression. RESULTS: Of 298 coconut IgE values, 90 (30%) were considered positive results, with a mean (SD) of 1.70 (8.28) kU/L. Macadamia had the strongest correlation (ρ = 0.77), whereas most other tree nuts had significant (P < .05) but low correlation (ρ < 0.5) with coconut. The adjusted odds ratio between coconut and macadamia was 7.39 (95% confidence interval, 2.60-21.02; P < .001) and 5.32 (95% confidence interval, 2.18-12.95; P < .001) between coconut and almond, with other nuts not being statistically significant. CONCLUSION: Our findings suggest that although sensitization to most tree nuts appears to correlate with coconut, this is largely explained by sensitization to almond and macadamia. This finding has not previously been reported in the literature. Further study correlating these results with clinical symptoms is planned.

Transcriptomics-based analysis using RNA-Seq of the coconut (Cocos nucifera) leaf in response to yellow decline phytoplasma infection.

Invasive phytoplasmas wreak havoc on coconut palms worldwide, leading to high loss of income, food insecurity and extreme poverty of farmers in producing countries. Phytoplasmas as strictly biotrophic insect-transmitted bacterial pathogens instigate distinct changes in developmental processes and defence responses of the infected plants and manipulate plants to their own advantage; however, little is known about the cellular and molecular mechanisms underlying host-phytoplasma interactions. Further, phytoplasma-mediated transcriptional alterations in coconut palm genes have not yet been identified. This study evaluated the whole transcriptome profiles of naturally infected leaves of Cocos nucifera ecotype Malayan Red Dwarf in response to yellow decline phytoplasma from group 16SrXIV, using RNA-Seq technique. Transcriptomics-based analysis reported here identified genes involved in coconut innate immunity. The number of down-regulated genes in response to phytoplasma infection exceeded the number of genes up-regulated. Of the 39,873 differentially expressed unigenes, 21,860 unigenes were suppressed and 18,013 were induced following infection. Comparative analysis revealed that genes associated with defence signalling against biotic stimuli were significantly overexpressed in phytoplasma-infected leaves versus healthy coconut leaves. Genes involving cell rescue and defence, cellular transport, oxidative stress, hormone stimulus and metabolism, photosynthesis reduction, transcription and biosynthesis of secondary metabolites were differentially represented. Our transcriptome analysis unveiled a core set of genes associated with defence of coconut in response to phytoplasma attack, although several novel defence response candidate genes with unknown function have also been identified. This study constitutes valuable sequence resource for uncovering the resistance genes and/or susceptibility genes which can be used as genetic tools in disease resistance breeding.

Characterizing the relationship between sesame, coconut, and nut allergy in children.

Sesame and coconut are emerging food allergens in the United States. We sought to examine whether children allergic to peanuts and tree nuts are at increased risk of having an allergy to sesame or coconut. We performed a retrospective chart review of children who underwent skin prick testing (SPT) to sesame and coconut and identified 191 children who underwent SPT to sesame and 40 to coconut. Sensitization to sesame was more likely in children with positive SPT to peanuts (odds ratio [OR] = 6.7, 95% confidence interval [CI] [2.7-16.8], p < 0.001) and tree nuts (OR = 10.5, 95% CI [4.0-27.7], p < 0.001). Children with histories of both peanut and tree nut reaction were more likely to have a history of sesame reaction (OR = 10.2, 95% CI [2.7-38.7], p < 0.001). Children with sensitization or allergy to peanuts or tree nuts were not more likely to be sensitized or allergic to coconut. In conclusion, children with peanut or tree nut sensitization were more likely to be sensitized to sesame but not coconut. Children with clinical histories of both peanut and tree nut allergy were more likely to be allergic to sesame.

The accumulation of dust mite allergens on mattresses made of different kinds of materials.

BACKGROUND: Different mattress materials may affect the accumulation of allergens. OBJECTIVE: To compare the amount of group 1 dust mite allergens (Der p1 + Der f1) on mattresses made of different kinds of materials before and after use. METHODS: Sixty new mattresses made of kapok, synthetic fiber, coconut fiber and sponge-like polyurethane, were placed in the house officers' dormitory at Siriraj hospital, Thailand. The dust samples were collected before (0), 1, 2, 3, 6, 9 and 12 months after the mattresses were used. Group 1 dust mite allergens were analyzed using two-site monoclonal antibody ELISA. RESULTS: Der f1 made up 86.7 % of group 1 allergens found in the matress dust. After the 2nd month, only the mean level in sponge-like polyurethane mattress was under 2 microg/g dust (sensitized level). At the 6th month, the mean levels were 13.1 in coconut, 21.7 in kapok and 17.3 microg/g dust in synthetic fiber, all of which were more than 10 microg/g dust (symptomatic level). At the 9th month, the level in sponge-like polyurethane mattress was increased to 11.2 microg/g. At 12th month the level in coconut fiber, sponge-like polyurethane synthetic fiber and kapok mattresses were 20.2, 22.4, 28.9 and 32.2 microg/g dust respectively. CONCLUSIONS: The accumulation rate in kapok and synthetic mattresses was significantly higher than coconut and sponge-like polyurethane mattresses. The mean level of group 1 mite allergens exceeded 10 microg/g dust after the 6th month of use in coconut fiber, kapok and synthetic fiber and at the 9th month in sponge-like polyurethane mattress.

Identification of a 7S globulin as a novel coconut allergen.

BACKGROUND: Coconut (Cocos nucifera) is a monocotyledonous plant of the Arecaceae family. Allergy to coconut is infrequent, with only 5 cases reported so far in the medical literature. OBJECTIVE: To identify coconut allergens in 2 patients allergic to this food. METHODS: We describe 2 patients allergic to coconut: an adult pollen-allergic patient monosensitized to coconut who presented with severe oropharyngeal symptoms and a child with a previous allergy to walnut, not allergic to pollen, who developed anaphylaxis on coconut ingestion. Both patients had positive skin prick test results and serum specific IgE (CAP) to coconut. IgE sodium dodecyl sulfate-polyacrylamide gel electrophoresis immunoblotting was performed to identify the allergens involved, and a strong IgE binding band detected in both patients was further analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS). Stability to pepsin digestion of the coconut extract and its cross-reactivity with tree nuts were studied. RESULTS: An immunoblot showed an almost identical profile of IgE binding proteins in the coconut extract in both patients who reacted strongly to a band of approximately 29 kDa. The peptide analysis by MALDI-TOF MS of this band obtained the sequence GHGKREDPEKR. The protein with the highest correlation with this peptide was found to be a 7S globulin from Elaeis guineensis, another oil palm species also belonging to the Arecaceae family. The 29-kDa band was digested by pepsin in less than 1 minute. Cross-reactivity among coconut, walnut, and hazelnut was demonstrated by CAP inhibition in patient 2. CONCLUSION: We have identified a 7S storage protein as a novel coconut allergen.

Cross-reactivity between coconut and hazelnut proteins in a patient with coconut anaphylaxis.

BACKGROUND: The medical literature reports few cases of severe allergic reactions to coconut. We encountered a patient with anaphylaxis to coconut and oral symptoms to tree nuts. OBJECTIVE: To identify cross-reactive antibodies between coconut and other tree nuts. METHODS: We performed commercial radioallergosorbent tests to coconut and various tree nuts using the patient's serum. Skin prick testing was performed to fresh coconut and commercial extracts of coconut, almond, Brazil nut, cashew, pecan, walnut, and hazelnut. Proteins from fresh coconut, commercial coconut extract, and tree nuts were extracted. Immunoblot and inhibition assays were performed to evaluate for cross-reacting IgE antibodies between similar-sized allergens in coconut and hazelnut. RESULTS: Positive skin test results occurred to the coconut and multiple tree nut extracts. In vitro serum specific IgE was present for coconut, hazelnut, Brazil nut, and cashew. Immunoblots demonstrated IgE binding to 35- and 50-kDa protein bands in the coconut and hazelnut extracts. Inhibition assays using coconut demonstrated complete inhibition of hazelnut specific IgE, but inhibition assays using hazelnut showed only partial inhibition of coconut specific IgE. CONCLUSIONS: Our study demonstrates the presence of cross-reactive allergens between hazelnut (a tree nut) and coconut (a distantly related palm family member). Because there are many potentially cross-reactive allergens among the tree nuts, we recommend patients with coconut hypersensitivity be investigated for further tree nut allergies.

A (1-->4)-beta-mannan-specific monoclonal antibody and its use in the immunocytochemical location of galactomannans.

Galactomannan was coupled to a protein carrier for the preparation of monoclonal antibodies. The monoclonal antibodies generated bound to galactomannans from different sources as well as to glucomannan and galactoglucomannan. One monoclonal antibody, BGM C6, was characterised and found to be specific for (1-->4)-beta-linked mannopyranosyl residues; it had a binding affinity estimated at 1x10(-6) M for the (1-->4)-beta-linked mannohexaose. BGM C6 was used in immunogold labelling studies to locate galactomannans in the endosperm walls of normal coconuts (Cocos nucifera L.) and those of the mutant makapuno at two different developmental stages. The pattern and intensity of antibody labelling varied for each type of coconut at the mature and immature stages, indicating differences in the galactomannan composition of the endosperm walls.

Systemic allergic reaction to coconut (Cocos nucifera) in 2 subjects with hypersensitivity to tree nut and demonstration of cross-reactivity to legumin-like seed storage proteins: new coconut and walnut food allergens.

BACKGROUND: Two patients with tree nut allergy manifested by life-threatening systemic reactions reported the subsequent onset of systemic reactions after the consumption of coconut. OBJECTIVE: Herein, the IgE-binding proteins from coconut are described, and in vitro cross-reactivity with other nuts is investigated. METHODS: The IgE-binding profile of coconut endosperm tissue extract was analyzed by SDS-PAGE followed by immunoblotting. Immunoblot inhibition studies with walnut, almond, peanut, and coconut were performed. RESULTS: Sera IgE from both patients recognized reduced coconut allergens with molecular weights of 35 and 36.5 kd. IgE from 1 patient also bound a 55-kd antigen. Preabsorption of sera with nut extracts suppressed IgE binding to coconut proteins. Preabsorption of sera with coconut caused the disappearance of IgE binding to protein bands at 35 and 36 kd on a reduced immunoblot of walnut protein extract in 1 patient and suppression of IgE binding to a protein at 36 kd in the other patient. CONCLUSION: The reduced coconut protein at 35 kd was previously shown to be immunologically similar to soy glycinin (legumin group of seed storage proteins). The clinical reactivity in these 2 patients is likely due to cross-reacting IgE antibodies primarily directed against walnut, the original clinical allergy reported, and most likely to a walnut legumin-like protein. Coconut allergy in patients with tree nut allergy is rare; these are the first 2 patients ever reported, and therefore there is no general indication to advise patients with tree nut allergy to avoid coconut.

Cocos nucifera pollen inducing allergy: sensitivity test and immunological study.

Among the heterogeneous population (n = 975) in greater Calutta, sensitization to Cocos nucifera pollen accounts to be 2.65% and for atopic patients (n = 204) 47.06%. Out of 24 patients who had C. nucifera pollen sensitivity and suffered from asthma and allergic rhinitis, 16 showed sensitivity also to other allergens. All were skin test positive and 19 of them were phadezym RAST positive to C. nucifera pollen extract. Bronchial provocation test appeared to be positive in 7 out of 8 patients included in the test and no late response or non-specific reactions were observed. C. nucifera pollen extract on fractionation by ion-exchange chromatography following gel filtration yielded two major allergenic protein fractions, CnII (M(r) 158,000) and CnVII (M(r) 2900) as evidenced by skin prick test, ELISA-inhibition and immunoblot analysis. Hence, C. nucifera pollen should be considered to be a relevant allergen and thus included in the panel of allergens for routine clinical use.

[A case of coconut oil allergy in an infant: responsibility of "maternalized" infant formulas]. / Un cas d'allergie à l'huile de noix de coco chez un nourrisson: responsabilité des laits maternisés.

The case is presented here of a baby of 8 months fed from her birth with maternal milks. The first milk induced a severe gastro-intestinal disorder which disappeared when a second milk was used. A third milk caused a relapse. The only common allergen was coconut, which was physico-chemically modified in the second milk. Demonstration of the responsibility of coconut oil was based on positive re-introduction tests, positive skin tests for coconut and maternal milk that were negative for cow's milk and peanut and by specific IgE tests which were positive in comparison with negative controls.