Anaphylaxis: guidelines from the European Academy of Allergy and Clinical Immunology

Anaphylaxis is a clinical emergency, and all healthcare professionals should be familiar with its recognition and acute and ongoing management. These guidelines have been prepared by the European Academy of Allergy and Clinical Immunology (EAACI) Taskforce on Anaphylaxis. They aim to provide evidence-based recommendations for the recognition, risk factor assessment, and the management of patients who are at risk of, are experiencing, or have experienced anaphylaxis. While the primary audience is allergists, these guidelines are also relevant to all other healthcare professionals. The development of these guidelines has been underpinned by two systematic reviews of the literature, both on the epidemiology and on clinical management of anaphylaxis. Anaphylaxis is a potentially life-threatening condition whose clinical diagnosis is based on recognition of a constellation of presenting features. First-line treatment for anaphylaxis is intramuscular adrenaline. Useful second-line interventions may include removing the trigger where possible, calling for help, correct positioning of the patient, high-flow oxygen, intravenous fluids, inhaled short-acting bronchodilators, and nebulized adrenaline. Discharge arrangements should involve an assessment of the risk of further reactions, a management plan with an anaphylaxis emergency action plan, and, where appropriate, prescribing an adrenaline auto-injector. If an adrenaline auto-injector is prescribed, education on when and how to use the device should be provided. Specialist follow-up is essential to investigate possible triggers, to perform a comprehensive risk assessment, and to prevent future episodes by developing personalized risk reduction strategies including, where possible, commencing allergen immunotherapy. Training for the patient and all caregivers is essential. There are still many gaps in the evidence base for anaphylaxis.

Food allergy in Alergológica-2005

BACKGROUND

Alergológica-2005 is a cross-sectional study carried out in Spain in 4991 new patients prospectively recruited in allergy clinics.

OBJECTIVE

To describe the characteristics of food allergic patients included in Alergológica-2005.

RESULTS

Food allergy was diagnosed in 369 subjects (7.4%, 95% CI, 6.7%-8.1%). The most common offending foods were fruits (33.3% of cases), nuts (26%), shellfish (22%), egg (16%), milk (13.9%) and fish (9.8%). Rosaceae fruits and crustaceans elicited 23.6% and 18.7% of the reactions, respectively. Milk and egg were the most common foods in patients < 5 years of age, whereas fruits and nuts were the most prevalent foods in patients over 5 years. The most frequent manifestations included skin reactions (65.3%), oral allergy syndrome (33.6%), digestive symptoms (24.7%) and anaphylaxis (17.9%). The clinical presentation differed among foods. Prick-tests were carried out more frequently than serum immunoglobulin E (IgE) determinations (95.9% vs. 65%). Oral challenges were performed in 13% of patients, and 72.3% of these were open. Food allergy was diagnosed on the basis of medical history and positive IgE in 60.2% of the patients, ranging from 13.7% for milk to 75% for cereals. The self perception of patients' quality of life was lower than that of the 75% of Spanish reference population.

CONCLUSION

Food allergy is diagnosed in 7.4% of the patients seen in allergy clinics across Spain, and has an important impact on the quality of life of patients. The foods involved in reactions change with age. The clinical presentation changes with the food, although the skin is the most frequently affected organ.

The role of profilin and lipid transfer protein in strawberry allergy in the Mediterranean area

BACKGROUND

In contrast to other Rosaceae fruit, only few cases of patients with adverse reactions to strawberry are listed in literature. OBJECTIVE To identify allergenic proteins in strawberry and to express and characterize recombinant strawberry lipid transfer protein (LTP; rFra a 3).

METHODS

Established apple-allergic patients were recruited on the basis of a reported allergic reaction to strawberry (n=28, confirmed by double-blind placebo-controlled food challenge in four patients) or on the basis of IgE reactivity to LTP (n=34). Sensitization to purified natural and recombinant allergens was assessed by RAST, immunoblot (inhibition) and basophil histamine release (BHR). A strawberry cDNA library was screened for genes homologous to known fruit allergens. Fra a 3 was cloned and expressed in the yeast Pichia pastoris and compared with peach and apple LTP by RAST, immunoblot-inhibition and BHR tests.

RESULTS

Genes homologous to Bet v 1, Bet v 6, profilin and LTP were identified in a strawberry cDNA library. In BHR the rFra a 3 induced histamine release at a 100-fold higher concentration than peach LTP. RAST inhibition showed high cross-reactivity to peach and apple LTP, although IgE reactivity was lower by a factor 5. On strawberry immunoblot, patients' IgE showed reactivity to a Bet v 1 homologue, profilin, LTP and high-molecular weight bands.

CONCLUSION

In addition to a Bet v 1 homologue, strawberry also contains IgE-binding profilin and LTP. The rFra a 3 has less allergenic potency than peach and apple LTP, and therefore is an interesting tool for future immunotherapy. Fra a 3 does not seem to be clinically relevant.

Retrospective study of tolerance to short initiation schedules in subcutaneous immunotherapy

With the aim of evaluating tolerance to new shorter initiation schedules in subcutaneous immunotherapy everyday clinical practice, a study was carried out using Pangramin Plus with initiation periods between 3 (Cluster) and 6 (Plus) weeks. All the information was processed retrospectively and both systemic (SR) and local (LR) adverse reactions occurring between September 2002 and February 2003 were recorded. A total of 353 patients (261 Plus and 91 Cluster) were included and 2,886 doses were administered (2,166 in initiation and 720 in maintenance). Of these, 800 were with Grass mix extract, 1,141 Grass mix + Olea, 273 Olea, 73 Dermatophagoides mix and 599 Dermatophagoides pteronyssinus. As regards adverse reactions (AR), 2.8% of patients showed SR and 4.8% LR, 1.2% of doses caused some type of reaction (SR and LR in 0.3% and 0.9%, respectively). The initiation schedule, first dose or allergens resulted in no significant differences in the frequency of adverse reactions. The Grass mix extract showed the highest frequency of AR. Sixty-seven percent of SR and 68% of LR were delayed. 64% of these reactions resolved spontaneously while the rest responded favourably to treatment. Adrenaline was administered on one occasion for immediate asthma. There were no cases of anaphylactic shock, hospitalisation or life-threatening situations. Pangramin Plus tolerance, therefore, can be classified as good, similar to conventional schedules, but with the benefits of shorter initiation schedules.

[Cross-reactivity between fruit and vegetables]

Vegetable foods are the most frequent cause of food allergy after the age of 5 years. The most commonly implicated foods are fruit and dried fruits, followed in Spain by legumes and fresh garden produce. In patients allergic to fruit and garden produce, multiple sensitizations to other vegetable products, whether from the same family or taxonomically unrelated, are frequent, although they do not always share the same clinical expression. Furthermore, more than 75 % of these patients are allergic to pollen, the type of pollen varying in relation to the aerobiology of the area. The basis of these associations among vegetable foods and with pollens lies in the existence of IgE antibodies against "panallergens", which determines cross-reactivity. Panallergens are proteins that are spread throughout the vegetable kingdom and are implicated in important biological functions (generally defense) and consequently their sequences and structures are highly conserved. The three best-known groups are allergens homologous to Bet v 1, profilins, and lipid transfer proteins (LTP). Allergens homologous to Bet v 1 (major birch pollen allergen) constitute a group of defense proteins (PR-10), with a molecular weight of 17 kDa, which behave as major allergens in patients from northern and central Europe with allergy to vegetables associated with birch pollen allergy. In these patients, the primary sensitization seems to be produced through the inhalation route on exposure to birch pollen. The symptomatology characteristically associated with sensitization to this family of allergens is oral allergy syndrome (OAS). Profilins are highly conserved proteins in all eukaryotic organisms and are present in pollen and a wide variety of vegetable foods. They have a molecular weight of 14 kDa and present a high degree of structural homology as well as marked cross-reactivity among one another. The presence of anti-profilin IgE broadens the spectrum of sensitizations to vegetable foods detected through skin tests and/or in vitro tests but whether it correlates with the clinical expression of food allergy is unclear.LTPs are the most commonly implicated allergens in allergy to Rosaceae fruits in patients from the Mediterranean area without birch pollen sensitization. LTPs are a family of 9kDA polypeptides, widely found in the vegetable kingdom and implicated in cuticle formation and defense against pathogens (PR-14). They are thermostable and resistant to pepsin digestion, which makes them potent food allergens and explains the frequent development of systemic symptoms (urticaria, anaphylaxis) in patients allergic to Rosaceae fruits in Spain. LTPs have also been identified in other vegetable foods and in pollens and a marked degree of cross-reactivity among them has been demonstrated, which may explain (together with profilin) the frequency of individuals sensitized to vegetable foods in the Mediterranean area.

Effect of nifedipine on skin prick tests

The immediate skin test due to interaction between allergen and mast cell bound IgE is one of the cornerstones in the clinical allergy workup. The release of histamine and other mediators from basophils and mast cells depends on the influx of Ca2+ into these cells when stimulated. The aim of this study was to evaluate the effect of common therapeutic doses of nifedipine (NFD), one of the calcium channel blockers, on the allergen skin tests. We prick tested 23 grass sensitive individuals with 7 different grass pollens at three times: at basal conditions (T0), 30 min. after having taken 20 mg of NFD s. l. (T1), and 17 of them after a week of receiving twice a day 20 mg of a NFD retard form (T2). The wheal surface obtained for each substance (allergen, histamine) at T0 was considered as basal value and compared with the one obtained at T1 and T2 for the same substance by the Wilcoxon's test. We found a significant increase in the wheal surfaces, both with allergen and histamine, at T1 and T2. In contrast to what could be expected, common therapeutic doses of NFD produce a discrete but statistically significant increase of the PT. Factors such as arteriolar vasodilation could be implicated. The increase of the allergen prick test and the increase of the histamine prick test both at T1 and T2 were not statistically different. Therefore, we do not think it necessary to stop NFD before allergen skin testing.

Stinging insect allergy: sensitization to vespids in Madrid and surroundings. Cross-reactivity study

The study comprised 28 patients from the centre of Spain (Madrid and surroundings) who had suffered systemic reactions when stung by vespids. Specific IgE antibodies to Vespula spp. and Polistes spp. venoms were measured by RAST. All patients had positive RAST to Vespula venom and half of them also had positive RAST to Polistes venom. A patient can be sensitive to both venoms due to either a clinical sensitization to both venoms, or common antigenic determinants. To differentiate these states we used a RAST inhibition assay. We could inhibit Polistes RAST with either Polistes or Vespula venom to a similar degree. Inhibition of Vespula RAST was possible with Vespula venom, but only to a limited degree with Polistes venom. Direct RAST and RAST inhibition studies indicate that in our geographic region sensitization to Vespula venom is more common than to Polistes venom and Polistes might have cross-reactivity in our patients.

Housewives with raw potato-induced bronchial asthma

Allergy to white potato has rarely been described. We report two cases of atopic patients, housewives, in whom peeling raw potatoes precipitated rhinoconjunctivitis and asthmatic attacks, and, in one of them, contact urticaria. Type I hypersensitivity to raw potato antigens was demonstrated by means of immediate skin test reactivity, specific IgE determination by RAST, basophil degranulation, histamine release test and an immediate bronchial provocation test response to raw potato extract. The controls did not react to any of these tests. Potato allergenic constituent is currently being investigated but, as far as we know, it is heat-labile and has an MW of more than 10 Kd.

Effect of insulin administration on water drinking in children

The effect of insulin administration on water intake, was studied in children submitted to standard protocols for stimulation of secretion of hypophyseal hormones by i.v. treatment with several different drugs: insulin, insulin plus TRH and LH-RH; and propranolol, clonidine or LH-RH. Drinking was measured from 0 to 90 min after drug administration; from blood samples taken at 60 min for hypophyseal hormones analysis, microhaematocrit values were measured, as well as plasma renin activity (PRA) and glycaemia. Water intake was significantly higher in both groups of patients receiving insulin than in the control group (no insulin). Haematocrit values did not change after 60 min. There was a significant correlation of glycaemia of individuals from all three groups and water intake at 60 min. PRA was significantly higher in insulin treated individuals.