Position paper of the EAACI: food allergy due to immunological cross-reactions with common inhalant allergens

In older children, adolescents, and adults, a substantial part of all IgE-mediated food allergies is caused by cross-reacting allergenic structures shared by inhalants and foods. IgE stimulated by a cross-reactive inhalant allergen can result in diverse patterns of allergic reactions to various foods. Local, mild, or severe systemic reactions may occur already after the first consumption of a food containing a cross-reactive allergen. In clinical practice, clinically relevant sensitizations are elucidated by skin prick testing or by the determination of specific IgE in vitro. Component-resolved diagnosis may help to reach a diagnosis and may predict the risk of a systemic reaction. Allergy needs to be confirmed in cases of unclear history by oral challenge tests. The therapeutic potential of allergen immunotherapy with inhalant allergens in pollen-related food allergy is not clear, and more placebo-controlled studies are needed. As we are facing an increasing incidence of pollen allergies, a shift in sensitization patterns and changes in nutritional habits, and the occurrence of new, so far unknown allergies due to cross-reactions are expected.

Cupressus arizonica pollen: a new pollen involved in the lipid transfer protein syndrome?

BACKGROUND

Lipid transfer proteins (LTP) are responsible for systemic manifestations in food allergy. Their relationship with pollinosis is not clear. In our area, many patients allergic to multiple LTP-containing foods present pollinosis due to Cupressus arizonica.

METHODS

We selected 6 patients with cypress pollinosis and food allergy to peach. Skin prick tests (SPT) were performed for pollens (grass, cypress, wall pellitory, plane tree, and olive tree) and plant foods (hazelnut, kiwifruit, peach peel, maize, wheat, peanut, lettuce, apple, mustard, and melon). In vitro assays included specific immunoglobulin (Ig) E to C arizonica and peach LTP (Pru p 3), enzyme allergosorbent test (EAST) inhibition, immunoblotting, immunoblotting-inhibition, and immunocytochemical techniques for the detection of Pru p 3-like LTP in cypress pollen grains.

RESULTS

SPT were positive for C arizonica, peach, lettuce, mustard, and hazelnut in all patients. Specific IgE to C arizonica and Pru p 3 was positive in all but 1 patient, whose Pru p 3 IgE was negative. Immunoblotting under nonreducing conditions with C arizonica extract and patients' sera showed a band at 14-15 kDa that was inhibited by Pru p 3. Pru p 3 partially inhibited the C arizonica pollen extract in EAST-inhibition. Pru p 3-like LTP was localized in the cytoplasm and walls of C arizonica pollen grains.

CONCLUSION

A 15-kDa allergen in C arizonica pollen was found in a group of patients presenting peach allergy and respiratory symptoms to cypress. In vitro tests and immunocytochemical techniques indicate that this protein is an LTP.

The non-specific lipid transfer protein, Ara h 9, is an important allergen in peanut

BACKGROUND

Plant food allergy in the Mediterranean area is mainly caused by non-specific lipid transfer proteins (nsLTP). The aim of this study was to characterize peanut nsLTP in comparison with peach nsLTP, Pru p 3, and assess its importance in peanut allergy.

METHODS

Peanut-allergic patients from Spain (n=32) were included on the basis of a positive case history and either a positive skin prick test or specific IgE to peanut. For comparison, sera of 41 peanut-allergic subjects from outside the Mediterranean area were used. Natural Ara h 9 and two isoforms of recombinant Ara h 9, expressed in Pichia pastoris, were purified using a two-step chromatographic procedure. Allergen characterization was carried out by N-terminal sequencing, circular dichroism (CD) spectroscopy, immunoblotting, IgE inhibition tests and basophil histamine release assays.

RESULTS

Compared with natural peanut nsLTP, the recombinant proteins could be purified in high amounts from yeast supernatant (> or =45 mg/L). The identity of the proteins was verified by N-terminal amino acid sequencing and with rabbit nsLTP-specific antibodies. CD spectroscopy revealed similar secondary structures for all preparations and Pru p 3. The Ara h 9 isoforms showed 62-68% amino acid sequence identity with Pru p 3. IgE antibody reactivity to rAra h 9 was present in 29/32 Spanish and 6/41 non-Mediterranean subjects. Recombinant Ara h 9 showed strong cross-reactivity to nPru p 3 and similar IgE-binding capacity as nAra h 9. The two Ara h 9 isoforms displayed similar IgE reactivity. In peanut-allergic patients with concomitant peach allergy, Ara h 9 showed a weaker allergenic potency than Pru p 3 in histamine release assays.

CONCLUSIONS

Ara h 9 is a major allergen in peanut-allergic patients from the Mediterranean area. Ara h 9 is capable of inducing histamine release from basophils, but to a lesser extent than Pru p 3.

An observational study on outgrowing food allergy during non-birch pollen-specific, subcutaneous immunotherapy

BACKGROUND

Birch pollen-specific immunotherapy (SIT) decreases allergy to foods containing birch pollen-homologous allergens. Cross-reactivity was also observed between plane tree pollen and some vegetable foods.

OBJECTIVE

The aim of this study was to evaluate the outgrowing of food allergy by patients suffering from vegetable food allergy associated with plane tree pollinosis (rhinoconjunctivitis and/or asthma) during plane tree pollen SIT.

METHODS

An observational and prospective study was conducted in 16 adult patients suffering from vegetable food allergy (hazelnut, walnut, lettuce, peach and cherry) and from plane tree pollinosis receiving plane tree pollen SIT for 1 year. Open oral challenges with the implicated food were performed before and after SIT. Blood samples were drawn for measurement of pollen- and food-specific IgE and IgG4 before and after treatment.

RESULTS

Plane tree SIT resulted in a significant decrease in food allergy, since the mean food quantity provoking objective symptoms increased from 2.19 to 13.74 g (p < 0.05), and 6 of the 11 patients tolerated the highest level (25 g) of the challenged food after plane tree SIT. Laboratory data also showed a decrease in IgE levels and an increase in IgG4 levels after immunotherapy.

CONCLUSION

SIT with plane tree pollen has a positive impact on food allergy in plane tree pollen-allergic subjects.

Purified allergens vs. complete extract in the diagnosis of plane tree pollen allergy

BACKGROUND

Plane tree pollen allergy is a clinical disorder affecting human population in cities of Europe, North America, South Africa, and Australia.

OBJECTIVE

To compare IgE-reactivity of the natural and recombinant forms of two major plane allergens, Pla a 1 and Pla a 2, with the reactivity of Platanus acerifolia pollen extract.

METHODS

Forty-seven patients with P. acerifolia allergy, 15 of them monosensitized, and 24 control subjects were included in the study. Natural Pla a 1 and Pla a 2 were purified by standard chromatographic methods and recombinant proteins were expressed in Escherichia coli. Skin prick test and determination of specific IgE were performed with commercial P. acerifolia extract and natural and recombinant purified allergens.

RESULTS

Pla a 1 and Pla a 2 were responsible for 79% of the IgE-binding capacity against P. acerifolia pollen extract. A high correlation has been found between the IgE response to nPla a 1 (R = 0.80; P < 0.001) or nPla a 2 (R = 0.79; P < 0.001) vs. P. acerifolia extract as well as between natural and recombinant Pla a 1 (R = 0.89; P < 0.001). Skin testing showed no significant differences between extract and nPla a 2, whereas a higher reactivity was found with nPla a 1. In contrast, rPla a 1 revealed markedly reduced sensitivity in comparison with extract by skin prick test and specific IgE. The sensitivity of the mix Pla a 1+Pla a 2 was 100% and 87.5% for monosensitized and polysensitized patients, respectively, with no false-positive reactions detected. Conclusion Pla a 1 and Pla 2 are sufficient for a reliable diagnosis of P. acerifolia in most patients and induce comparable skin test reactivity as a whole extract.

A critical assessment of allergen component-based in vitro diagnosis in cherry allergy across Europe

BACKGROUND

Food allergy to cherry occurs throughout Europe, typically with restricted oral reactions in the central and northern parts but with frequent systemic reactions in the Mediterranean region. Previous studies have demonstrated insufficient sensitivity of commercially available cherry extract reagents in the diagnosis of cherry allergy.

OBJECTIVE

To assess the diagnostic performance of specific IgE tests based on recombinant cherry allergens in comparison with an extract-based assay and to skin prick test (SPT). A secondary objective was to analyse the frequency of systemic reactions in cherry-allergic subjects across Europe, including the largest population of LTP-sensitized subjects from central Europe studied to date.

METHODS

A total of 186 subjects from central Europe and Spain were studied. Serum IgE was analysed with ImmunoCAP tests carrying rPru av 1, 3 and 4, combined and separately, and cherry extract.

RESULTS

Among the central European cherry allergics, the mix of rPru av 1, 3 and 4 had a sensitivity of 95%, compared with 65% for cherry extract, and the IgE binding capacity of the recombinant mix was considerably higher. The sensitivity of the two tests was more comparable in the Spanish population, 95% and 86%, respectively. The recombinant allergen ImmunoCAP equalled SPT in terms of sensitivity and specificity. Consistent with previous reports, major geographic differences in sensitization pattern and prevalence of systemic reactions were found. A significantly higher rate of systemic reactions was found in Spanish patients sensitized to Pru av 3 whereas German patients sensitized to LTP only had oral allergy syndrome.

CONCLUSIONS

The recombinant cherry allergen ImmunoCAP is a highly sensitive diagnostic tool, clearly superior to any diagnostic method based on cherry extract. Three cherry allergens are sufficient for detecting sensitization in 95% of cherry-allergic subjects. Systemic reactions are common in LTP-sensitized individuals but seem to require at least one additional causative factor.

Double-blind, placebo-controlled study of immunotherapy with Parietaria judaica: clinical efficacy and tolerance

Allergy to Parietaria causes significant morbidity in most Mediterranean areas. The aim of this study is to investigate the efficacy and tolerance of Parietaria depot extract at 25 BU/mL (1.5 microg/mL Par j 1). We performed a multicenter double-blind, placebo-controlled study in rhinitic patients with/without asthma, sensitized to Parietaria. 42 patients followed 20-month immunotherapy. Clinical efficacy was based on symptom and medication scores and the percentage of healthy days (days without symptoms or medication). Severity of asthma/rhinitis scales, visual analogue scale, evaluation of the treatment by doctors and patients, immediate and delayed cutaneous response and quality of life questionnaires were also studied. The active group showed a sustained decrease in symptoms (p = 0.008), medication (p = 0.009) and both (p = 0.001), and an increase in healthy days (p = 0.001) throughout the study, with a threefold increase of healthy days and almost a three time reduction in medication only after one year of treatment. Asthma and rhinitis severity scales also decreased after immunotherapy, and blinded clinical evaluation by physicians confirmed efficacy in 85% and 77% of the active patients. Patient's self-evaluation returned similar results. None of these changes were observed with placebo. Immediate cutaneous response was significantly reduced at the maintenance phase in the active group and remained reduced throughout the study. Late-phase response after intradermal testing also showed a statistical decrease in actively treated patients. Immunotherapy was well tolerated and every systemic reaction reported was mild. In conclusion, immunotherapy with Parietaria 25 BU/mL is an effective and safe treatment for patients with respiratory allergies.

Tolerance and effects on skin reactivity to latex of sublingual rush immunotherapy with a latex extract

BACKGROUND

Specific immunotherapy could be a therapeutic tool for the increasing problem of sensitisation to Natural Rubber Latex (NRL).

OBJECTIVE

To investigate the tolerability of SLIT for Latex and its effects on skin reactivity.

METHODS

Twenty-six patients (mean age 35.5 years) with an average history of 7.5 years of cutaneous symptoms plus respiratory symptoms (23/26) due to NRL were studied. All underwent rush sublingual therapy (4 days) with a standardized NRL extract followed by a 9-week maintenance treatment. Local and systemic adverse reactions were monitored throughout the treatment. Skin reactivity to NRL extract was evaluated before, during and at the end of the treatment by latex glove-use test, rubbing test and skin prick test.

RESULTS

All patients reached the maintenance dose. Out of 1044 administered doses, 257 (24.6%) produced adverse reactions from which 21.4% were local. Only 10.1% of cases required treatment, mainly with antihistamines alone (5.8%), with 2-agonists alone (0.8%) or associated to antihistamines and/or corticosteroids (2.7%). One patient was precautionary treated twice with adrenaline but completed the treatment without further problems. The glove-use test improved significantly after 5 days and 10 weeks of treatment (p = 0.003, p = 0.0004 respectively), whereas the rubbing test improved significantly only after 10 weeks of treatment. Doctor's assessments confirmed the results obtained with the glove-use test (p = 0.003 after 5 days, and p = 0.004 after 10 weeks) but not those obtained with the rubbing test. No change was detected for SPTs.

CONCLUSION

SLIT for NRL allergy is able to modify skin reactivity to NRL in days as assessed with methods reproducing HCWs normal exposure to the allergen. Tolerance of SLIT is better than tolerance reported for injective therapy with NRL, but the build up phase should be administered under medical surveillance until sufficient experience has been accumulated. The long-term effect of the treatment deserves further investigation.

IgE reactivity to profilin in Platanus acerifolia pollen-sensitized subjects with plant-derived food allergy

BACKGROUND

The presence of profilin-specific IgE antibodies is a cause of cross-reactivity between botanically-unrelated allergen sources. Recently, the association between Platanus acerifolia pollinosis and plant-derived food allergy has been described. The aim of this study was to ascertain whether the P. acerifolia profilin is involved in such cross-reactivity.

METHODS

Twenty-three patients suffering from Platanus acerifolia pollinosis and plant-derived food allergy were evaluated in an allergy department. Specific IgE levels to P. acerifolia pollen, P. acerifolia profilin and food extracts were measured. Molecular masses of IgE-binding proteins were calculated by Western blotting and cross-reactivity studies among P. acerifolia profilin and different food extracts were evaluated by Enzyme AllergoSorbent Test (EAST)-inhibition assays. Also, EAST-inhibition assays with the two known P. acerifolia allergens, Pla a 1 and Pla a 2, were performed.

RESULTS

Surprisingly, a high IgE-binding prevalence (90%) of P. acerifolia profilin was found. EAST-inhibition showed high inhibition values when Platanus acerifolia pollen extract was used as free phase and plant-derived food extracts as solid phase, whereas the other way round showed low inhibition values. IgE reactivity to profilin was studied using a pool of patient sera, by EAST-inhibition assays with hazelnut, apple peel, peanut, chickpea and peanut extracts as solid phase and no inhibition was obtained when P. acerifolia profilin was used as inhibitor phase. The same results were obtained when purified Pla a 1 and Pla a 2 were also used as inhibitor phase.

CONCLUSIONS

The clinical association observed between Platanus acerifolia pollen and plant-derived food could be explained by the in vitro IgE cross-reactivity detected by EAST-inhibition. However, it appears that neither P. acerifolia profilin nor the two major allergens described (Pla a 1 and Pla a 2) can explain such a strong cross-reactivity.

Lettuce anaphylaxis: identification of a lipid transfer protein as the major allergen

BACKGROUND

Allergy to plant-derived foods is associated with birch pollinosis in central and northern Europe. Symptoms elicited are usually limited to the oropharyngeal system. By contrast, in the Mediterranean area, allergy to the same foods manifests more frequently with systemic reactions caused by nonspecific lipid transfer proteins (nsLTP), independently of an associated pollinosis.

OBJECTIVE

We sought to investigate the pattern of immunoglobulin E (IgE) binding protein bands implicated in lettuce allergy, in particular the presence of an nsLTP.

METHODS

Consecutive lettuce allergic patients were selected. Determination of serum-specific IgE, immunoblot, and inhibition experiments were performed in order to study the pattern of IgE binding proteins and the potential cross-reactivity to pollens. Inhibition studies with recombinant allergens were conducted to identify the lettuce allergens. The major allergen was subjected to N-terminal amino acid sequencing.

RESULTS

Fourteen patients were diagnosed as being allergic to lettuce. All were sensitized to Platanus pollen. Ten of them showed specific IgE to a lettuce protein of 9-kDa. The IgE binding to this protein was completely inhibited by the cherry-LTP and peach extract. The N-terminal sequence of the 9-kDa protein showed a high degree of amino acid sequence identity to other nsLTPs. A clear partial cross-reactivity was observed between lettuce-LTP and Platanus-pollen extract.

CONCLUSIONS

An LTP has been demonstrated to be a major allergen in patients suffering from lettuce allergy.

Recurrent urticaria as a rare manifestation of familial Mediterranean fever

Familial Mediterranean fever (FMF) is a genetic disorder characterized by acute episodes of fever with some combination of severe abdominal pain, pleurisy, arthritis, and skin rash. The case of a patient with recurrent urticaria referred for study of drug allergy is presented. After allergy had been ruled out, the urticaria was attributed to previously undiagnosed symptoms of an underlying systemic disease: FME. Urticaria is the least frequent cutaneous manifestation of this disease, and genetic analysis was required to confirm the diagnosis.

Efficacy of the eradication of Helicobacter pylori infection in patients with chronic urticaria. A placebo-controlled double blind study

Helicobacter pylori has been involved in the pathogenesis of chronic idiopathic urticaria (CIU) in patients suffering both CIU and H. pylori infection. We selected 49 patients with 13C urea breath test positive, long-lasting CIU and H. pylori infection; 20 remained symptomatic, had positive urease test or H. pylori histologic identification in gastric biopsy material and accepted to participate in a pacebo-controlled treatment trial. They were randomized for a 7-day, double-blind, placebo-controlled H. pylori eradication treatment with amoxicillin, clarithromycin and omeprazol or placebo. H. pylori eradication was assessed by a second 13C urea breath test six weeks after the end of treatment. We observed a significant improvement of more than 70 % of CIU; baseline clinical score was seen in 4 of the 9 (44 %) patients who eradicated H. pylori after active treatment and in 1 of the 7 (12,3 %) of those who did not (p = 0.19). No clinical differences in CIU characteristics were found between patients with and without improvement. No serious adverse effects were observed in either treatment group. We conclude that the eradication of H. pylori may be useful for patients suffering long-lasting CIU and H. pylori infection, although theses results did not reach statistical significance probably owing to the strict conditions of the recruitment.

Platanus acerifolia pollinosis and food allergy

BACKGROUND

In Mediterranean areas, oral allergy syndrome (OAS) occurs independently of an associated birch pollinosis; moreover, on occasions it presents with no other associated pollinosis. The aim of this study was to assess the possible association of OAS with Platanus acerifolia pollinosis.

METHODS

We evaluated consecutive patients seen for pollinosis in an allergy department. Seven hundred and twenty patients were selected on the basis of seasonal or perennial rhinitis, or asthma, or both. Respiratory and food allergies were studied in all patients. Clinical history was recorded and examinations and skin prick tests were performed with a battery of available common inhalant allergens and plant-derived food allergens. Specific IgE levels to P. acerifolia pollen extract and food allergens tested were measured. Molecular masses of the IgE-binding proteins and cross-reactivity among the P. acerifolia pollen and different food extracts were also determined.

RESULTS

Of the 720 patients evaluated, 61 (8.48%) were sensitized to P. acerifolia pollen. Food allergy was observed in 32 (52.45%) of the 61 patients sensitized to P. acerifolia pollen. Food allergens most frequently implicated were hazelnuts, peach, apple, peanuts, maize, chickpea and lettuce. Enzyme allergosorbent (EAST)-inhibition showed high inhibition values when P. acerifolia pollen extract was used as free phase. On the contrary low inhibition was observed when plant-derived food allergens were used as free phase and P. acerifolia pollen extract as solid phase.

CONCLUSIONS

Cross-reactivity was observed among P. acerifolia pollen and plant-derived foods. OAS in these patients may have been caused by primary respiratory sensitization.

Allergy to Diplotaxis erucoides pollen: occupational sensitization and cross-reactivity with other common pollens

BACKGROUND

Diplotaxis erucoides is a common weed of the Brassicaceae family widespread in southern and central Europe.

METHODS

A total of 410 consecutive patients referred for allergy study of rhinoconjunctivitis and/or asthma were skin tested with D. erucoides pollen, 14 proving positive. A purified D. erucoides pollen extract was prepared to perform quantitative skin tests, provocation tests, immunoblotting, and EIA inhibition in the 14 sensitized patients.

RESULTS

Three patients, directly involved in viniculture, had rhinoconjunctivitis related to D. erucoides pollen. No D. erucoides-related symptoms were observed in most patients, who were also sensitized to Artemisia pollen. RAST was positive in 12/14 patients and nasal provocation tests in 9/12. The molecular masses of the most prevalent IgE-binding proteins ranged from 26 to 27.5 and from 31 to 34 kDa. D. erucoides pollen inhibited the IgE-binding of other sensitizing pollens in the three viniculture workers, whereas both Artemisia and D. erucoides pollen produced similar heterologous inhibition in the pooled serum of the remaining, nonclinically affected, D. erucoides-sensitized patients.

CONCLUSION

D. erucoides pollen may be an important prevalent aeroallergen, particularly in rural areas. It may act as an occupational allergen in vineyard workers, in whom it seems to be the primary sensitizing agent, playing a secondary cross-reactive role in other sensitized patients.

Successful treatment of chronic idiopathic urticaria associated with thyroid autoimmunity

The prevalence of thyroid autoimmunity is high in patients with chronic idiopathic urticaria (CIU), but in few selected patients the possible clinical benefit of levothyroxine sodium or antithyroid drugs has been studied. The objective of the present study was to confirm the prevalence of antithyroid antibodies in patients with CIU and to investigate the clinical response to levothyroxine sodium or methimazole. Antithyroglobulin and antiperoxidase antibodies were measured in 170 consecutive patients with CIU. Twenty-five (14.7%) had an antithyroglobulin or antiperoxidase antibody levels > 180 lU/ml and all but three were women. Twenty patients with CIU and thyroid autoimmunity were treated with levothyroxine sodium if hypothyroidism or normal thyroid function were present (18 patients) and with methimazole if hyperthyroidism was detected (two patients). Clinical response was evaluated by a clinical score. Autologous serum skin test before treatment was performed in 18 patients with thyroid autoantibodies. Urticaria resolved rapidly in two patients with Graves' disease. The clinical response of urticaria to levothyroxine sodium treatment was good in 15 patients and partial in two, whereas only one patient showed no improvement in clinical score (p < 0.0005). No changes in the antithyroglobulin or antiperoxidase levels were detected. Five patients reported adverse effects. The autologous serum skin test was positive in 10 patients and negative in eight. After successful treatment the test was repeated in six patients, proving negative in four and significantly diminished in two. We concluded that patients with CIU and thyroid autoimmunity benefit from treatment with levothyroxine sodium or antithyroid drugs. Antithyroid antibodies and positive autologous serum skin test in these patients could be markers of autoimmune disease with several target organs.

Chronic urticaria associated with chronic myelomonocytic leukemia

Although chronic urticaria is usually idiopathic, in rare cases it may be a sign of underlying malignancy. We describe the first case of chronic urticaria associated with chronic myelomonocytic leukemia. The urticarial lesions healed successfully with etoposide, an antineoplastic agent. This case demonstrates that cases of chronic urticaria should not to be labeled as idiopathic until diligent evaluation has failed to reveal a cause.

Disseminated and recurrent sarcoid-like granulomatous panniculitis due to bovine collagen injection

Three to five percent of patients treated with injectable collagen implants have adverse local reactions. Systemic signs or symptoms are infrequent. We describe the case of a 53-year-old woman who developed local and general complaints 2 months after receiving two collagen injections in both nasolabial folds. She presented asthenia, malaise, polyarthralgia and inflammatory nodular panniculitis in the places of injection as well as on the forearms and lower extremities. Skin testing was compatible with hypersensitivity to collagen. This case raises the question as to whether the injection of animal-derived collagen induces manifestations similar to those observed in connective autoimmune diseases or human adjuvant disease.

Usefulness of UniCAP-Tryptase fluoroimmunoassay in the diagnosis of anaphylaxis

BACKGROUND

Serum tryptase level measured by RIA is the main in vitro tool to confirm the diagnosis of anaphylaxis.

METHODS

Serum tryptase levels were determined by UniCAP-Tryptase fluoroimmunoassay (Pharmacia & Upjohn, Uppsala, Sweden), in 30 consecutive patients who presented at the emergency room with a clinical allergic reaction of less than 6-h duration to assess the value of this method in the diagnosis of anaphylaxis. Anaphylaxis was established by clinical criteria and by immunoallergic study. Baseline tryptase levels were determined 1 month later in 21 patients. The receiver operating curve (ROC) was used to establish the best cutoff point of tryptase levels to confirm the diagnosis of anaphylaxis.

RESULTS

Seventeen patients were diagnosed with anaphylaxis. In this group, tryptase levels were higher than in the nonanaphylaxis group, composed mostly of patients with urticaria or angioedema (P<0.001). ROC established the best cutoff of tryptase levels at 8.23 ng/ml with a 94.12% sensitivity and 92.31% specificity, whereas the 13.5 ng/ml cutoff recommended by the manufacturers showed 35.29% sensitivity and 92.31% specificity. The reaction-tryptase/baseline-tryptase ratio was 2.85 in the anaphylaxis group and 1.29 in the nonanaphylaxis group.

CONCLUSIONS

Serum tryptase levels of >8.23 ng/ml by UniCAP-Tryptase fluoroimmunoassay identify anaphylaxis in patients with symptoms of less than 6-h duration. The usefulness of this determination is higher if baseline tryptase levels are available.

Asthma, mite sensitization, and sleeping in bunks

BACKGROUND

Mattresses and bedding are the main reservoirs of house dust mites.

OBJECTIVE

Subjects sleeping in the bottom bunk may be exposed to house dust particles detached from bedding of the top bunk. Our aim was to ascertain whether this exposure could influence the development of mite sensitization and/or allergic symptoms in these individuals.

METHODS

Symptoms of allergic respiratory disease were recorded and mite skin tests performed in 94 consecutive bunk-sleeping subjects (47 pairs of siblings) from an outpatient allergy clinic. Levels of Der p I, Der f I, and Der II were determined by enzyme-immunoassay in 16 randomly selected bedding dust samples (8 pairs of bunks).

RESULTS

Mite sensitization rate and prevalence of allergic respiratory disease were similar for the top-bed and bottom-bed groups, whereas prevalence of asthma was significantly higher in the latter. Mite sensitization was significantly associated with family atopy background, whereas other factors such as house pets, indoor smoke exposure or types of mattress or bunks were not. Der p I levels higher than 2 microg/g dust were found in 12 of the 16 mattresses and the median of the 8-bed-bottom group was over 10 microg/g.

CONCLUSIONS

Sleeping in bunks constitutes a greater risk of developing asthma for subjects sleeping in the bottom bed. Bunk sleeping should be discouraged in families with an atopic background and sensitized subjects should use the top bed.

Serum sickness-like syndrome due to mosquito bite

Local inflammatory reactions at the site of a mosquito bite are frequent. Immediate systemic reactions have occasionally been reported. The first case of a patient with relapsing episodes of a serum sickness-like syndrome following mosquito bites is reported herein. A 62-year-old patient came to the emergency room complaining of sudden malaise, chills, fever, headache, cervical lymph node enlargement, arthromyalgia, generalized purpura and leukopenia 6 h after a mosquito bite. He had experienced multiple similar episodes in the last 20 years, also following mosquito bites. Infectious and autoimmune diseases were ruled out. Serum IgE was 9,102 kU/l. Prick test of whole-body Culex pipiens extract was positive. Specific IgE to Aedes communis was 2.25 kU/l. SDS-PAGE immunoblotting of the patient's serum with whole-body C. pipiens extract revealed 43 and 17 kDa IgG-binding proteins and 22 and 17 kDa IgE-binding proteins, neither of which were found with control sera. Skin biopsy was consistent with leukocytoclastic vasculitis. The presence of both mosquito-specific IgE and IgG in the patient's serum suggest a possible cooperative immune response leading to clinical manifestations of serum sickness.

Evaluation of the left ventricular performance through equilibrium radionuclide angiocardiography

In patients with severe heart failure due to acute myocardial infarction (AMI) breathing with PEEP can be of additional therapeutic value. This study was designed to assess the effects of CPAP through face mask with 15 cm H2O on left ventricular performance in AMI patients, using equilibrium radionuclide angiocardiography (ERA). In response to lung inflation, high levels of PEEP have been shown to decrease heart rate and stroke volume. The sum of the TPF pathological prolongation and the Mean-FR reduction suggests a decrease in the left ventricular compliance determined by the restriction imposed by the positive pressure. The global systolic performance is preserved.

[Acute respiratory failure in chronic obstructive lung disease. Effective weaning and excess base]

To establish whether the weaning from assisted mechanical ventilation (AMV) should be accompanied by continuous respiratory support (synchronized intermittent mandatory ventilation [SIMV]) or discontinuous support (O2 in T) in patients affected by chronic obstructive lung disease (COLD) who are recovering from acute respiratory failure (ARF), and also to identify any possible predictive value of gasometric measurements. Sixteen patients with COLD and ARF were studied prospectively during their stay in the intensive care unit. Ten had acute bronchitis, 3 had left ventricular failure and 2 had pneumonia. In 1 case the etiology was unknown. The following protocol was used for the first attempt at weaning: 1) SIMV for 30 min, 2) return to rest period with AMV for 2 hours, 3) O2 in T-tube for 30 min. After 30 min both SIMV and O2 in T had produced a rise in PaCO2 to 55.1 and 54.6 mmHg, respectively (p < 0.001), with a subsequent lowering of pH to 7.32 and 7.36 (p < 0.001). When weaning was well tolerated, pH decreased significantly due to an increase in PaCO2 with both techniques, while base excess (BE) remained stable. Values of pH also decreased significantly when weaning was poorly tolerated, and the fall was greater with SIMV; increases in PaCO2 were similar, but decreases in BE were significant. When pH is kept within normal range by a high BE, the withdrawal of AMV, accompanied by either support system, is usually well-tolerated.

Modifications of tissular oxygenation and systemic hemodynamics after the correction of hypocapnia induced by mechanical ventilation

The modifications of systemic hemodynamics, oxygen transport and tissular oxygenation in mechanically-ventilated critical ARF (acute respiratory failure) patients, after the correction of its hypocapnia by addition of dead space (VD) are determined. The prospective and randomized study was carried out in a multidisciplinary ICU. Fifteen ARF patients were studied within the first 48 hours of evolution. All the patients were intubated and mechanically ventilated. Three stages were delimited: I) 30 min after the beginning of anesthesia; II) 30 min after adding 30 cm of VD; III) 30 min after replacing the previous VD with a VD of 60 cm. Similar steady states had been reached when the measurements were taken. Ventilation parameters and FiO2 were kept stable. In stage I the patients presented a pure respiratory alkalosis and, with respect to hemodynamics, a hyperdynamic situation. In stage II the acid-base balance was normalized with a continuation of the hyperdynamic situation and an increase in mixed venous oxygen tension and saturation (PvO2 and SvO2) (p < 0.001). Stage III was characterized by a pure hypercapnic acidosis and an increase in capillary wedge pressure (CWP) (p < 0.05), right atrial pressure (RAP) (p < 0.001) and cardiac output (Qt) (p < 0.001); simultaneously, the systemic vascular resistances (SVR) decreased (p < 0.01), the PvO2, SvO2 and oxygen delivery (DO2) increased (p < 0.001); oxygen utilization coefficient (OUC) decreased (p < 0.01). The results suggest that the variations in PvO2 and SvO2 are a direct consequence of the modifications in blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)