The skin prick test.

The skin prick test (SPT) is the most common test for the diagnosis of allergy. SPT is performed by pricking the skin, usually in the volar surface of the forearm, with a lancet through a drop of an allergen extract and is usually the first choice test in the diagnostic workup for allergic diseases because of its reliability, safety, convenience and low cost. SPT is minimally invasive and has the advantage of testing multiple allergens in 15 to 20 min. In children, SPT is far less disturbing than venipuncture and is used to obtain a sample of serum to measure specific IgE through in vitro tests. There is a good correlation (about 85-95%) between SPT and in vitro tests. Globally, SPT is an excellent diagnostic tool, with a positive predictive value ranging from 95-100%. SPTs can identify sensitivity to inhalants, foods, some drugs, occupational allergens, hymenoptera venom and latex. However, the relevance of such sensitivity to allergens should always be carefully interpreted in the light of the clinical history, because sensitization and clinical allergy may not coincide. In regards to safety, though the reports of systemic reactions, and particularly anaphylaxis, are very rare, in vitro IgE tests should be preferred if previous severe reactions emerge from the patient’s clinical history.

Seroepidemiology of HEV and HAV in two populations with different socio-economic levels and hygienic/sanitary conditions.

The epidemiological scenarios of hepatitis E virus (HEV) and hepatitis A virus (HAV) infections have changed in the last few decades, but precise epidemiological data on the prevalence of anti-HEV and anti-HAV, alone or in combination, in the general population are scanty. We investigated HEV and HAV seroprevalence comparing two population samples living in Northern (Abbiategrasso, Milan) and Southern Italy (Cittanova, Reggio Calabria), the latter being characterized by a poorer socio-economic level and hygienic/sanitary conditions. Based on census records, we randomly enrolled and tested 3,365 subjects (Abbiategrasso, n = 2,489; Cittanova, n = 876) aged 18-75 years for anti-HAV and anti-HEV. Anti-HAV (71.3 % vs 52.5 %) and anti-HEV (17.8 % vs 9.0 %) prevalence rates were higher in Southern Italy (both p < 0.001). Most anti-HEV-positive subjects also had anti-HAV. Subjects testing positive for anti-HAV, alone or with anti-HEV, were older (p < 0.001 in both populations) and showed a trend toward declining prevalence in the youngest birth cohorts. The prevalence of subjects with a positive result for anti-HEV alone did not change in birth cohorts in the two towns. Detection of anti-HEV was independently associated with anti-HAV, town, birth cohort, and education level in multivariate analysis. Low socio-economic level and hygienic/sanitary conditions are associated with high HAV and HEV seroprevalence rates in Italy. Recent improvements, especially in the South, have led to a declining prevalence of anti-HAV, alone or with anti-HEV. Seroprevalence of HEV alone is uniformly low and does not change in birth cohorts born between 1938 and 1993.

Hyponatremia is a predictor of hospital length and cost of stay and outcome in cancer patients.

PURPOSE: Hyponatremia is the most common electrolyte disorder in hospitalized patients, and it might be an indicator of poor prognosis and might have negative effects on hospitalization length and quality of life in non-malignant as well as in malignant diseases. The aim of this study is to determine the impact of hyponatremia on the length and on the cost of hospitalization as well as on outcome in cancer patients. METHODS: The present study includes 105 consecutive cancer patients hospitalized at our institution from June 2013 to December 2013. Data regarding age, sex, staging, histology, chemotherapy, and serum sodium levels at admission, during hospitalization, and at discharge were recorded and statistically analyzed. Impact of hyponatremia on length and cost of hospitalization and on outcome was evaluated. RESULTS: A significant difference in overall survival since the date of admission was observed between eunatremic and hyponatremic patients (p = 0.0255). A statistically significant correlation was also found between the length of stay and the detection of hyponatremia. At multivariate analysis, hyponatremia at admission, severity of hyponatremia, and stage of disease resulted independent prognostic factors. Furthermore, a patient with moderate or severe hyponatremia cost, in rate terms, 128 and 299 % more than a normonatremic patient, respectively. CONCLUSIONS: The occurrence of hyponatremia at the admission or during the hospitalization may represent a significant factor influencing the outcome and the length of hospitalization. Acting effective and timely on the normalization of sodium levels might have a positive effect on prognosis in this setting of patients, as well as on the length of stay in hospital, thus potentially resulting in savings.

Increased rates of local complication of central venous catheters in the targeted anticancer therapy era: a 2-year retrospective analysis.

PURPOSE: Totally implantable central venous accesses (port-a-cath) are often used for chemotherapy administration or prolonged intravenous infusions in cancer patients. Local and systemic complications may occur both during and after placement of port-a-cath despite the well-established techniques for its placement and care. Out of other catheter-related local complications, thrombosis and infections represent the most common. Complications related to central venous catheter may be associated with infusion of both conventional chemotherapy and molecularly targeted therapy. Incidence and nature of complications of central venous catheter have been well established for long-term chemotherapy. However, very sparse data exists on the incidence of complications of molecularly targeted therapies administered through a central venous catheter. Hence, we decided to retrospectively analyze the local complications of a central venous catheter in patients receiving molecularly targeted therapy and conventional chemotherapy, respectively. METHODS: Over a 2-year period, 459 devices were placed in two academic Italian institutions. Patients' characteristics, catheter-related complications, and their relationship with targeted therapy administration were retrospectively assessed. RESULTS: Catheter-related complications occurred in 30 out of the 459 analyzed cancer patients (7 %). Local complications occurred in 12 (40 %) and 18 (60 %) patients receiving standard chemotherapy and biological drugs, respectively. Eighteen (72 %) out of 25 patients developing biological complications (BC) were receiving biological drugs. Infusion of a biological drug through a central venous catheter has been shown to increase the risk of central venous catheter complications (p = 0.02). No difference between the incidence of complication between anti-angiogenic and anti-epidermal growth factor receptor (EGFR) agents was observed in our study despite the statistically significant early development of port-a-cath complication in the anti-EGFR group. Treatment with a biological drug and the stage of disease, in univariate analysis, had independent effect on the duration for development of catheter-related complications. CONCLUSIONS: Molecularly targeted therapy may influence the occurrence of BCs, i.e., infection and dehiscence. Onset of BCs occurred earlier in patients receiving biological drugs (more frequently with bevacizumab than with anti-EGFR therapy) than those undergoing traditional chemotherapy. Further studies are needed to ascertain the findings of our study and to elucidate the reason for the higher incidence of catheter-related complications.

Which allergen extract for grass pollen immunotherapy? An in vitro study.

BACKGROUND: Grass pollen is a major cause of allergy throughout the world. The only treatment targeting the causes and not only the symptoms of allergy is specific immunotherapy (IT). A number of controlled trials demonstrated the efficacy of IT in grass pollen allergic subjects, most using extracts of multiple grasses but some using extracts of a single grass. The optimal grass extract for IT has not yet been established. METHODS: This study is aimed at investigating the IgE-binding pattern in sera from IT-naïve patients from central Italy with allergic rhinitis and/or asthma caused by grass pollen. A 5-grass extract was used (containing Dactylis glomerata, Poa pratensis, Lolium perenne, Antoxanthum odoratum and Phleum pratense) and compared to Phleum pratense alone, which is the most frequently used single grass extract, by the RAST-inhibition technique. RESULTS: The 5-grass extract showed, by RAST-inhibition, a significantly higher binding compared to the Phleum pratense extract for Antoxanthum odoratum and Poa pratensis, while the two extracts for immunotherapy showed similar binding affinity for Phleum pratense and the non-Pooideae grass, Cynodon dactylon. CONCLUSIONS: The use of a mixed-grass pollen extract seems to be the optimal choice when applying specific IT in grass pollen-allergic subjects from the Mediterranean area.

Infant swimming in chlorinated pools and the risks of bronchiolitis, asthma and allergy.

Recent studies suggest that swimming in chlorinated pools during infancy may increase the risks of lower respiratory tract infection. The aim of the present study was to assess the influence of swimming in chlorinated pools on the risks of bronchiolitis and its late consequences. A total of 430 children (47% female; mean age 5.7 yrs) in 30 kindergartens were examined. Parents completed a questionnaire regarding the child's health history, swimming practice and potential confounders. Attendance at indoor or outdoor chlorinated pools ever before the age of 2 yrs was associated with an increased risk of bronchiolitis (OR 1.68; 95% CI 1.08-2.68; p = 0.03), which was exposure-dependent for both types of pool (p-value for trend <0.01). Associations persisted, and were even strengthened, by the exclusion of other risk factors. Among children with no parental antecedents of atopic disease or no day-care attendance, odds ratios for bronchiolitis amounted to 4.45 (1.82-10.9; p = 0.001) and 4.44 (1.88-10.5; p = 0.007) after >20 h spent in chlorinated pools during infancy. Infant swimmers who developed bronchiolitis also showed higher risks of asthma and respiratory allergies later in childhood. Swimming pool attendance during infancy is associated with a higher risk of bronchiolitis, with ensuing increased risks of asthma and allergic sensitisation.

The future of sublingual immunotherapy.

Sublingual immunotherapy (SLIT) is currently the most prescribed form of allergen immunotherapy in many European countries. Its use has been accepted in the international consensus publications, and recently also the scepticism of USA scientists is attenuated. Still, this treatment may be improved, and the possible developments consist of modification of the materials, use of adjuvants and use of recombinant allergens. Moreover, new applications of SLIT, such as food allergy, seem promising. Concerning materials, the future form of SLIT is likely to be represented by tablets, which were already tested for efficacy and safety with grass pollen extracts, and are likely to increase the convenience for the patient by the use of no-updosing schedule. Adjuvants fitting with the characteristics of SLIT seem to be CpG oligodeoxynucleotides (CpG), able to interact with the Toll-like receptor 9 (TLR9) whose activation induces a Th1-like pattern of cytokine release, combination of 1,25-dihydroxyvitamin D3 plus dexamethasone (VitD3-Dex), and Lactobacillus plantarum. The approach with recombinant allergens, named component-resolved diagnosis, offers the possibility to tailor immunotherapy, which was found to be effective in two randomized trials of subcutaneous SIT (16-17), while studies with SLIT are not yet available. Regarding food allergy, an important controlled study demonstrated that SLIT with hazelnut is able to increase patients tolerance over possible reactions from inadvertent assumption of the culprit food, and warrants for further trials with other foods.

Lack of inflammatory cells in the oral mucosa of subjects undergoing sublingual immunotherapy.

The cells involved in allergic inflammation, such as mast cells, basophils, and eosinophils, have been thoroughly studied in the nose, the lungs and the skin, demonstrating an evident increase in response to the introduction of the specific allergen, while little is known in the mucosal system and particularly in the oral mucosa. We investigated such tissue by using the model of sublingual immunotherapy (SLIT), by which high doses of the specific allergen enter the mouth. Oral biopsies were carried out on seven subjects allergic to grass pollen and treated with SLIT by a grass extract. In biopsies carried out before SLIT there was a very low number of mast cells and eosinophils both in the epithelium and subepithelium layers, and insignificant changes were detected after SLIT. These findings show the lack of allergic inflammation in the oral mucosa upon contact with the specific allergen and confirm the role of the mouth as a tolerogenic site, which is conceivable considering the different attitude of the mouth, where the antigens transit to undergo digestion, in respect to the airways or the skin, where the antigen absorption is potentially dangerous.

Allergy and the gastrointestinal system.

The gastrointestinal system plays a central role in immune system homeostasis. It is the main route of contact with the external environment and is overloaded every day with external stimuli, sometimes dangerous as pathogens (bacteria, protozoa, fungi, viruses) or toxic substances, in other cases very useful as food or commensal flora. The crucial position of the gastrointestinal system is testified by the huge amount of immune cells that reside within it. Indeed, gut-associated lymphoid tissue (GALT) is the prominent part of mucosal-associated lymphoid tissue (MALT) and represents almost 70% of the entire immune system; moreover, about 80% of plasma cells [mainly immunoglobulin A (IgA)-bearing cells] reside in GALT. GALT interacts strictly with gastrointestinal functions in a dynamic manner; for instance, by increasing intestinal permeability in replay to particular stimulations, or orientating the immune response towards luminal content, allowing either tolerance or elimination/degradation of luminal antigens, or sometimes provoking damage to the intestinal mucosa, such as in coeliac disease or food allergy. The immune mechanisms implicated in these actions are very complex and belong to both innate and adaptive immunity; innate immunity supplies an immediate non-specific response that is indispensable before specific adaptive immunity, which needs 7-10 days to be efficacious, takes place. The results of their interactions depend upon different contexts in which contact with external agents occurs and may change according to different genetic settings of the hosts.

Allergen specific nasal challenge to latex in children with latex allergy: clinical and immunological evaluation.

There are no data concerning the significance of allergen specific nasal challenge to latex (ASNCL) in the pediatric population and the effect of mometasone furoate nasal spray (MFNS), topic corticosteroid exerting a potent anti-inflammatory activity in children with latex allergic rhinitis. The aims of this study are: to investigate the clinical and immune pathological effects of ASNCL in children with latex allergy; to study the effects of MFNS pre-medication on the clinical and immune pathological effects of ASNCL in children with latex allergy. Thirteen children: 6 male and 7 female, mean (SD) age 9.6 (2.9) years, with latex allergy and seven children: 3 male and 4 female, mean (SD) age 9.9 (3.8) years, without latex allergy underwent ASNCL. Nasal symptoms were recorded, nasal lavage fluid was collected to measure tryptase, eosinophil cationic protein (ECP), interleukin-5, interferon-gamma levels, and spirometric test was performed for each patient without or with premedication with MFNS. ASNCL induced a clinical allergic response and increased tryptase levels only in children with latex allergy. No serious adverse events occurred after ASNCL. MFNS premedication reduced both tryptase and ECP levels only in children with latex allergy. ASNCL is a simple, reliable and useful tool to make or confirm the diagnosis of nasal symptoms due to latex; it allows us to study both clinical symptoms and local immunological changes. MFNS premedication before an ASNCL may prevent some immunological responses induced by ASNCL without clinical allergic modifications.

Comparison between continuous or intermittent schedules of sublingual immunotherapy for house dust mites: effects on compliance, patients satisfaction, quality of life and safety.

Sublingual immunotherapy (SLIT) is indicated in the treatment of allergic rhinitis and asthma. However, an issue scantly investigated is the patients satisfaction and the consequent compliance. This study is aimed at evaluating the possible differences of SLIT administered continuously or intermittently on several parameters: clinical efficacy, Quality of Life (QoL), satisfaction, compliance and safety. Forty allergic patients were treated for 12 months. The treatment was carried out by sublingual administration of an allergen extract of a 50% mixture of Dermatophagoides pteronyssinus and Dermatophagoides farinae at 10 and 300 IR/ml concentrations. Patients were randomly treated continuously or intermittently (i.e. 2 month treatment alternate to 2 month suspension). Both schedules were significantly effective in reducing allergic symptoms and improving QoL. Compliance and satisfaction were good in both groups. Local and systemic reactions were few, self-resolving, and mild in both schedules. Intergroup analysis did not reveal any difference between the two groups regarding these parameters. In conclusion, this preliminary study provides the evidence that also intermittent SLIT is as effective and safe as traditional continuous treatment. In addition, compliance and satisfaction are super-imposable in the two groups.

Sublingual immunotherapy: from safety to mechanism of action.

Allergen specific immunotherapy is an important option for the treatment of respiratory allergy and its clinical efficacy has been clearly demonstrated by several studies. However, the injective route of administration and the possibility of severe side effects has limited its use in children and led to the introduction of new forms of administration. Sublingual immunotherapy (SLIT) has proven to be an effective and safe treatment for respiratory allergy. However, its mechanism of action is still debated. Pharmacokinetic studies showed that, differently from nasal mucosa, allergen extracts administered by SLIT are not immediately adsorbed but are long retained before being drained to local lymph nodes. This difference may be responsible of the absence of severe side effects and instead of short-lasting local symptoms. Studies by biopsies of the oral mucosa should greatly help in defining the presence and the role of cells involved in the mechanisms of oral tolerance.

Lower airway inflammation before and after house dust mite nasal challenge: an age and allergen exposure-related phenomenon.

BACKGROUND: Upper and lower airways allergic disease is currently considered unitarily. Allergic inflammation in one site can extend to other sites of the respiratory tract. OBJECTIVE: To evaluate bronchial inflammation before and after allergen-specific nasal challenge (ASNC) in rhinitic and asthmatic children, considering the different levels of allergen exposure, i.e. summer (low) and winter (high). METHODS: Fourteen children with rhinitis and 15 with rhinitis and asthma, all monosensitized to mites and 10 healthy controls were studied. Nasal IgE were measured before ASNC in summer and in winter season. Nasal clinical score, eosinophil cationic protein (ECP), nasal tryptase, bronchial clinical score, FEV(1), PEF, sputum ECP, sputum tryptase and exhaled nitric oxide (eNO) were evaluated before and after ASNC in summer and winter season. RESULTS: Nasal scores significantly increased after ASNC in rhinitic and asthmatic children in both seasons. Nasal IgE were significantly higher in summer compared to winter. Bronchial symptoms, FEV(1) and PEF showed no mean differences in rhinitic and asthmatic children after ASNC, with an increase of bronchial symptoms and a decrease of FEV(1) and PEF occurring in 3/15 asthmatic children. In both groups nasal tryptase and ECP after ASNC significantly increased in summer and winter, while sputum tryptase was undetectable before or after ASNC in both groups. Sputum ECP and eNO at baseline were significantly higher in patients than in controls (summer P=0.002, winter P=0.001). Sputum ECP significantly increased after ASNC in 3/15 asthmatics in summer and in 11/15 in winter, as well as in 3/14 rhinitics in summer and in 4/14 in winter. eNO significantly increased after ASNC in 3/15 asthmatics in summer and in 10/15 in winter, and in 1/14 rhinitics in summer and in 4/14 in winter. A significant median increase of sputum ECP (P=0.0007) and eNO (P=0.0012) after ASNC in asthmatic and of eNO (P=0.013) in rhinitic children was also found in winter. CONCLUSIONS: Basal sputum ECP and eNO values, significantly higher before ASNC in rhinitic patients compared to control subjects, confirm the inflammatory link of upper and lower airways. The more frequent detection of inflammatory changes induced by ASNC in winter suggests that allergen exposure favours the transfer of nasal inflammation to lower airways.

Pharmacoeconomics of subcutaneous allergen immunotherapy.

The current burden of allergic diseases, estimated by both direct and indirect costs, is very relevant. In fact the cost estimation for rhinitis amount globally to 4-10 billion dollars/year in the U.S. and to an average annual cost of 1089 euros per child/adolescent and 1543 euros per adult in Europe. The estimated annual costs in Northern America for asthma amounted to 14 billion dollars. Consequently, preventive strategies aimed at reducing the clinical severity of allergy are potentially able to reduce its costs. Among them, specific immunotherapy (SIT) joins to the preventive capacity the carryover effect once treatment is discontinued. A number of studies, mainly conducted in the US and Germany demonstrated a favourable cost-benefit balance. In the nineties, most surveys on patients with allergic rhinitis and asthma reported significant reductions of the direct and indirect costs in subjects treated with SIT compared to those treated with symptomatic drugs. This is fully confirmed in recent studies conducted in European countries: in Denmark the direct cost per patient/year of the standard care was more than halved following SIT; in Italy a study on Parietaria allergic patients demonstrated a significant difference in favor of SIT plus drug treatment for three years versus drug treatment alone, with a cost reduction starting from the 2nd year and increasing to 48% at the 3rd year, with a highly statistical significance which was maintained up to the 6th year, i.e. 3 years after stopping immunotherapy, corresponding to a net saving for each patient at the final evaluation of 623 euros per year; in France a cost/efficacy analysis comparing SIT and current symptomatic treatment in adults and children with dust mite and pollen allergy showed remarkable savings with SIT for both allergies in adults and children.

Economic evaluation of sublingual immunotherapy: an analysis of literature.

Allergic rhinitis and asthma constitute a global health problem because of their very high prevalence and the consequent burden of disease, concerning medical and economical issues. Among the treatments of allergy, specific immunotherapy has the capacity to favourably alter the natural history of the disease both during and after its performance and thus to reduce the direct and indirect costs of allergic rhinitis and asthma. A number of studies reported such cost reduction for traditional, subcutaneous immunotherapy and recent data demonstrate that also sublingual immunotherapy (SLIT) is associated to economic advantages and/or monetary savings, specifically in terms of reduction of disease economic burden. Only few formal economic assessments of SLIT have been carried out so far, this article will present and discuss the published studies addressed to this issue. The data obtained, although the number of studies is still limited, provide preliminary evidence supporting a SLIT effect on sparing costs for respiratory allergy.

Dose dependence of efficacy but not of safety in sublingual immunotherapy.

Sublingual immunotherapy (SLIT) currently represents, as indicated by meta-analysis of its efficacy and safety, a valid option to the generally used traditional subcutaneous immunotherapy (SCIT) for treating respiratory allergy. Regarding efficacy, recent studies demonstrated that, similar to what has already been observed in SCIT as well as in experimental and clinical studies about the magnitudo of allergen exposure, the effectiveness on both clinical symptoms and immunologic changes depends on the amount of allergen administered during treatment. In addition, in vitro studies addressed with the role of dendritic cells, currently considered to be of pivotal importance in orienting toward tolerance the immune response to allergens, showed that the internalisation of allergen molecules, which is followed by tolerogenic presentation to T cells, depends on the amount of allergen. However, such dose dependence is not apparent concerning the safety. In fact, the comparison of studies respectively conducted with high and low allergen doses did not show differences in the rate of systemic reactions, which in any case never had the presentation of anaphylaxis, and instead a significant difference in the rate of local reactions, following the oral and gastrointestinal contact with the allergen extract, in favour of high dose studies.

Practice parameters for sublingual immunotherapy.

The efficacy and safety of sublingual immunotherapy (SLIT) are currently supported by clinical trials, meta-analysis and post-marketing surveys. Practice parameters for clinical use of SLIT are proposed here by a panel of Italian specialists, with reference to evidence based criteria. Indications to SLIT include allergic rhinoconjunctivitis, asthma, and isolated conjunctivitis (strength of recommendation: grade A). As to severity of the disease, SLIT is indicated in moderate/severe intermittent rhinitis, persistent rhinitis and mild to moderate asthma (grade D). SLIT may be safely prescribed also in children aged three to five years (grade B), and its use in subjects aged more than 60 years is not prevented when the indications and contraindication are ascertained (grade D). The choice of the allergen to be employed for SLIT should be made in accordance with the combination of clinical history and results of skin prick tests (grade D). Polysensitisation, i.e. the occurrence of multiple positive response does not exclude SLIT, which may be done with the clinically most important allergens (grade D). As to practical administration, co-seasonal, pre co-seasonal, and continuous schedules are available, being the latter recommended for perennial allergens or for pollens with particularly prolonged pollination, such as Parietaria (grade D). For pollens with relatively short pollination, such as grasses and trees (cypress, birch, alder, hazelnut, olive) the pre co-seasonal and perennial schedules are preferred (grade C). The build-up phases suggested by manufacturers can be safely used (grade A), but they can be modified according to the patient's tolerance (grade C). A duration of SLIT of 3-5 years is recommended to ensure a long-lasting clinical effect after the treatment has been terminated (grade C).

Sublingual reactivity to rBET V1 and rPHL P1 in patients with oral allergy syndrome.

Oral Allergy Syndrome (OAS) in patients with pollen-induced rhinoconjunctivitis is caused by specific IgE recognizing cross-reacting epitopes of fruits and plants, which were clearly shown in vitro, but failed to be demonstrated in vivo by cross-challenges in the target organs. Considering the hypothesis of degradation of such epitopes in natural extracts, challenges with recombinant pollen allergens were done to evaluate the reactivity of the oral mucosa in OAS patients. Seventeen patients with OAS and rhinitis from birch (10) and grass pollen (7) and 10 non-atopic controls were studied by skin prick tests (SPT), allergen specific nasal challenges (ASNC) and allergen specific sublingual challenges (ASSC) with birch and timothy extracts and with rBet v1 and rPhl p1 at increasing concentrations from 1 to 1000 mcg/ml. None of the healthy subjects in the control group had any positive test for birch and timothy extracts or for recombinant allergens. In the OAS group the following results were observed: SPTs with recombinant allergens were positive in all patients, mostly at 10 mcg/ml concentration; ASNC with rBet v1 were positive in all patients, mostly at 100 mcg/ml; ASSC with natural pollen extracts were positive in only 2 of 17 patients, but in 15 of 17 with rBet v1 and rPhl p1, mostly at 500 mcg/ml and 1000 mcg/ml. ASSC with rBet v1 and rPhl p1 were positive with a mean concentration of 677 and 533 mcg/ml, respectively. The results of sublingual challenges with rBet v1 and rPhl p1 showed the in vivo cross-reactivity between pollens and foods in patients with OAS, but high concentrations of the recombinant allergens were needed to reproduce oral symptoms, thus explaining the failure of challenges performed with natural extracts, which have concentrations of major allergens lower than 50 mcg/ml. This indicates that sublingual mucosa is much less reactive to allergens than other surfaces, such as skin and nasal mucosa, probably because of its anatomic and immunologic peculiarity.