IgE-mediated reactivity to non-specific lipid transfer protein (nsLTP): clinical implications and management ‒ consensus document of the Association of Italian Territorial and Hospital Allergists and Immunologists (AAIITO)

Summary

The primary cause of adult-onset food allergy in Mediterranean countries is IgE-mediated reactivity to non-specific Lipid Transfer Protein (nsLTP), with a prevalence of 9.5% in Italy. nsLTP is heat- and pepsin-stable due to its 3D structure, causing severe allergic reactions, even anaphylaxis. It's conserved across plants and a "panallergen" due to homologous forms in various vegetable foods. Found in Rosaceae fruits' skin, it's categorized into nsLTP1 (9 kDa) and nsLTP2 (7 kDa), representing 93% and 7% of the molecules described to date, respectively. Pru p 3 (nsLTP1) from peach is a primary sensitizer, binding more epitopes than other homologs. Cross-reactivity varies in sensitized patients, influenced by IgE levels. Clinical manifestations range from none to various symptoms. Managing patients sensitized to nsLTP without clinical allergy is a challenge. Sensitization hierarchy usually starts with peach, then expands through Prunoideae, Rosaceae, and other foods. Clinical symptoms don't always expand across LTPs. Patients can tolerate some nsLTP-containing foods and consuming them may maintain tolerance. The absence of guidelines led to the Associazione Allergologi Immunologi Italiani Territoriali e Ospedalieri (AAIITO) creating a consensus-based document. Strategies involve avoidance, self-injectable adrenaline, verification through in vivo and in vitro testing, considering cofactors, and peeling fruits. In localized reactions, abstinence is recommended if specific IgE is high. Concurrent pollinosis may complicates diagnosis, but may help management since symptoms are often less severe. Asymptomatic patients are advised to continue normal diets while considering cofactors and total IgE levels. Management strategies should be case-specific, based on expert Consensus Document.

Clinical severity of LTP syndrome is associated with an expanded IgE repertoire, FDEIA, FDHIH, and LTP mono reactivity

Summary

Background. LTP allergy is often a challenge for clinicians. We evaluated a multiplex diagnostic approach with diverse cofactors to stratify LTP syndrome risk. Methods. Of the 1,831 participants screened with 'Allergy Explorer-ALEX-2', 426 had reactions to at least one LTP. Data was gathered and recorded via an electronic database. Results. Reactivity to peach Pru p 3 was found in 77% of individuals with LTP allergy. Higher levels of specific IgE and concurrent sensitization to more than 5 molecules (50% of all LTP-sensitised participants, 62% of symptomatic cases) were significantly associated with an increased risk of severe reactions (p = 0.001). Several cofactors, either alone or in combination, also influenced patients' clinical outcomes. Some cofactors increased the risk of severe reactions, such as mono reactivity to LTP in 44.6% of cases (p = 0.001), FDEIA in 10.8% of patients (p = 0.001), and FDNIH in 11.5% (p = 0.005). On the other hand, reactivity to PR10 (24.2%; p = 0.001), profilin hypersensitivity (10.3%; p = 0.001), and/or atopic dermatitis (16.7%; p = 0.001) had a mitigating effect on symptom severity. Conclusions. Clinical severity of LTP syndrome is associated with an expanded IgE repertoire in terms of the number of LTP components recognized and increased IgE levels in individual molecules. Ara h 9, Cor a 8, and Mal d 3 showed the strongest association with clinical severity. In addition, several cofactors may either exacerbate (FDEIA, FDHIH, and LTP monoreactivity) or ameliorate (atopic dermatitis and co-sensitization to profilin and/or PR10) individual patient outcomes. These factors may be utilized for the daily clinical management of LTP syndrome.

Why lipid transfer protein allergy is not a pollen-food syndrome: novel data and literature review

Summary

Background.Based on the cross-reactivity between pollen lipid transfer proteins (LTPs) and the peach LTP, Pru p 3, it has been suggested that the pollen might initiate the LTP sensitization process. Objective. To establish whether LTP allergy can be considered as a pollen-food syndrome. Methods. The literature was reviewed and new data of component-resolved diagnosis from Italy obtained by both ISAC immunoassay and ImmunoCAP on large populations of LTP hypersensitive patients were provided and analyzed. Results. Among Pru p 3 reactors, patients positive for Art v 3 and Pla a 3 largely exceeded those sensitized to the respective major pollen allergens, Art v 1 and Pla a 1/Pla a 2. Pru p 3 reactivity remained stable around 80-90% at all ages, whereas Art v 3 and Ole e 7 recognition was missing in younger patients. Pru p 3 IgE exceeded IgE specific for pollen LTP at all ages. Inhibition studies carried out on LTP reactors showed that commercial extracts of mugwort and plane pollen were unable to inhibit significantly Pru p 3 IgE reactivity. In follow-up studies, baseline Pru p 3 IgE levels exceeded Art v 3 IgE levels in 84% of those sensitized to both allergens, and all patients positive to only one LTP allergen at baseline were sensitized to Pru p 3. Further, most of the patients who did not show any LTP reactivity at baseline became exclusive Pru p 3 reactors. On ImmunoCAP singleplex Pru p 3 IgE levels exceeded Art v 3 IgE levels in 89% of cases (p less than 0.0001). Most literature data were in keeping with these new observations. Conclusions. The evidence for LTP syndrome being a pollen-food syndrome is presently very thin. Our data do not rule out the possible sensitization to the protein, via the airways or the skin.

Evaluation and predictive value of IgE responses toward a comprehensive panel of house dust mite allergens using a new multiplex assay: a real-life experience on an Italian population

Summary

Background. House dust mites (HDM) are among the most important allergen sources worldwide, representing a major cause of perennial allergic rhinitis and asthma. Aim. To evaluate the prevalence of IgE responses towards a comprehensive panel of HDM allergens and to evaluate the implications of molecular sensitization profiles on respiratory symptoms. Methods. 155 consecutive HDM-allergic patients (mean age: 27.5 years; range: 1-62; female: 63), 86 affected by rhinitis and 68 by asthma, were enrolled. Specific IgE reactivity to Der f 1, Der p 1, Der f 2, Der p 2, Der p 5, Der p 7, Der p 10, Der p 11, Der p 20, Der p 21 and Der p 23 was tested in patients' sera using the last version of the multiparametric assay Allergy Explorer (ALEX). Results. In all, major and minor allergens were positive, respectively, in 96.8% and 50.9% of the patients. Prevalence and IgE levels of Der f 1, Der f 2, Der p 1 and Der p 20 were significantly higher in asthmatic patients (p less than 0.05), whereas subjects negative for minor allergens resulted more frequently suffering from rhinitis (p = 0.0001). Asthmatic patients had IgE reactivity to a larger number of HDM allergens (mean 5.4; SD ± 2.3) than patients with only rhinitis (mean 4.2; SD ± 2.5) (p = 0.003), whereas no differences in the number of HDM positive molecules and in the specific IgE levels were found among different ages. Conclusions. This study confirms that the assessment of IgE to a comprehensive panel of HDM allergens defines different serological reactivity profiles that seem associated with different clinical presentations.

Comparison of the performance of Skin Prick and ISAC Tests in the diagnosis of allergy

Summary

The recent European Union and Italian regulations in the matter of in vivo test could strongly impact on current diagnostic approach, increasing the usage of in vitro tests in daily clinical practice. We evaluated 506 patients with both skin prick test and a microarray system (ImmunoCAP ISAC 112). The overall evaluation between ImmunoCAP^® ISAC vs SPT showed a moderate agreement (k=0.509, 95% C.I. 0.480-0.540, SE: 0.016) considering both aeroallergens and food allergens. When we considered the concordant results (double-positive plus double-negatives), the agreement ranged from 69% to 80% for pollen allergens, between 74% and 76% for dust mites, and between 74% and 93% for animal epithelia. In the case of food allergens, the accordance was pretty lower, accounting values ranging from 67% to 86%. ISAC testing identified from 22% to 26% more cases than SPTs in peach and nuts hyper-sensitivity. In 2.8% of the control group, the ISAC-test failed to detect an allergy sensitization caused by dust mite, shrimp, Anisakis, or seed storage proteins. Multiplex testing is more than a promising tool for more precise and comprehensive profiling of allergic patients and can be considered as a second-line approach, after the anamnesis, in the diagnosis of allergic diseases.

House dust mite allergy and shrimp allergy: a complex interaction

Summary

Background and Objective. Sensitization and allergy to shrimp among Italian house dust mite allergic patients are not well defined and were investigated in a large multicenter study. Methods. Shrimp sensitization and allergy were assessed in 526 house dust mite (HDM)-allergic patients submitted to the detection of IgE to Der p 10 and 100 atopic control not sensitized to HDM. Results. Shrimp allergy occurred in 9% of patients (vs 0% of 100 atopic controls not sensitized to HDM; p minor 0.001). Shrimp-allergic patients were less frequently hypersensitive to airborne allergens other than HDM than crustacean-tolerant subjects (35% vs 58.8%; p minor 0.005). Only 51% of tropomyosin-sensitized patients had shrimp allergy, and these showed significantly higher Der p 10 IgE levels than shrimp-tolerant ones (mean 22.2 KU/l vs 6.2 KU/l; p minor 0.05). Altogether 53% of shrimp-allergic patients did not react against tropomyosin. Conclusions. Shrimp allergy seems to occur uniquely in association with hypersensitivity to HDM allergens and tropomyosin is the main shrimp allergen but not a major one, at least in Italy. Along with tropomyosin-specific IgE levels, monosensitization to HDM seems to represent a risk factor for the development of shrimp allergy among HDM allergic patients.

Evaluation of two commercial peach extracts for skin prick testing in the diagnosis of hypersensitivity to lipid transfer protein. A multicenter study

Summary

The clinical usefulness of two commercial peach extracts for SPT (by Lofarma SpA and ALK-Abellò, respectively) was compared in a multicenter study carried out in Italy. Peach allergic patients were tested with the two extracts in parallel and underwent the detection of IgE specific for all three peach allergens currently available (Pru p1, Pru p3, and Pru p4, respectively). The two extracts were almost identical in terms of sensitivity and specificity, being able to detect virtually all patients sensitized to stable peach allergens (lipid transfer protein (LTP) and, presumably, peamaclein) but scoring negative in patients exclusively sensitive to labile allergens (either PR-10 and/or profilin). Thus, the two extracts represent an excellent tool to carry out a preliminary component-resolved diagnosis of peach allergy at the first patient visit.

Recommendations for the Use of Tryptase in the Diagnosis of Anaphylaxis and Clonal Mastcell Disorders

Summary

Tryptase is a serin-protease produced and released by mast cells after IgE-mediated or non-IgE mediated stimuli. We here review the various aspects related to the molecular characteristics of the enzyme and its biological effects, the genetic basis of its production and the release kinetics. Recommendations for the clinical use of tryptase measurement developed by a task force of Società Italiana di Patologia Clinica e Medicina di Laboratorio and Associazione Allergologi Immunologi Italiani Territoriali e Ospedalieri are given on the best procedure for a correct definition of the reference values in relation to the inter-individual variability and to the correct determination of tryptase in blood and other biological liquids, in the diagnosis of anaphylaxis (from drugs, food, insect sting, or idiophatic), death from anaphylaxis (post mortem assessment) and cutaneous or clonal mastcell disorders.

Galactose-α-1,3-galactose syndrome: an Italian survey

Summary

Background. The term of α-Gal syndrome, which includes the delayed allergy to red meat and the allergic reactions following the administration of cetuximab, is associated to the presence of specific IgE to α-Gal. In Italy, only anecdotal cases were reported so far. The Association of Italian Allergists (AAITO) carried out a survey with the aim of evaluating presence, characteristics, clinical features, and distribution of the syndrome in Italy. Methods. A web structured questionnaire was made available on the website of AAIITO from July 2016 to January 2017. It included 31 multiple-choice questions concerning different items, including the site of physicians, the number of patients diagnosed as having cetuximab allergy and/or delayed red meat allergy, recall of tick bites, symptoms, time to reactions, elicitor foods, reactions with foods other than meat, and in-vivo and in-vitro tests used for the diagnosis. Results. Seventy-nine physicians completed the questionnaire. Nine cases of allergy to cetuximab and 40 cases of delayed red meat allergy were recorded across Italy. 22.5% of patients with cetuximab allergy and 62.5% of those with delayed red meat allergy recalled a tick bite. 75% of patients with delayed red meat allergy experienced symptoms after eating beef (butcher's cut in 72.5%). Urticaria was the most frequent clinical manifestation (65% of cases). In 60.6% of cases symptoms appeared 2 - 4 hours after meat ingestion, while in 7.9% symptoms appeared after > 4 hours. The most used diagnostic methods were the intradermal test for cetuximab allergy (88.9%) and the detection of IgE to α-Gal (55.5%) for red meat allergy. Most case reports came from Northern Italy. Conclusions. α-Gal syndrome is present in Italy and beef is the most frequent offending food. In most cases symptoms were not severe.

Frequency of allergic sensitization to Can f 5 in North East Italy. An analysis of 1403 ISACs 112 (Component Resolved Diagnosis) collected retrospectively

Summary

Recent studies have shown the increasing relevance of allergic sensitization to Can f 5, a prostatic kallicrein expressed in the prostate and detectable only in male dogs. The aim of the present study was to establish the frequency, level of sensitization and association with other dog allergens of Can f 5, as assessed by Component Resolved Diagnosis (CRD- ISAC 112, ThermoFisher Scientific, Uppsala, Sweden), in North East Italy. A total of 1403 CRD ISAC 112 were examined retrospectively. Five-hundred twenty subjects (37 %) had a positive IgE response to at least one of the available animal allergens. Among these 520 subjects, 268 (51.5 %) showed at least one sensitization to dog allergens. Among dog-sensitized individuals, 183 (69.02%) showed IgE against Can f 5, and 106 (57.92%) were sensitized exclusively against Can f 5. The average Can f 5 specific IgE was 8.810 ISU-E, with 77.6 % of individuals showing medium or high values of specific IgE according to manufacturer's specifications. In conclusions, our data confirmed that there is a high number of sensitized patients to Can f 5, which have a high degree of allergic sensitization. These results should be taken into account by allergists managing dog allergic patients. In fact, clinical consequences of this sensitization regard respiratory allergy (burden of rhinitis/asthma), systemic reactions (anaphylaxis during sexual intercourse from cross-reaction with human prostatic antigen), allergen immunotherapy-AIT (likely ineffective in patients with exclusive sensitization), and preventive measures (possibility to own a female dog and a likely reduction of allergen passive transport). Further studies are needed to better explore these aspects in "real life".

Molecular diagnostics improves diagnosis and treatment of respiratory allergy and food allergy with economic optimization and cost saving

BACKGROUND

Component resolved diagnosis (CRD) allows to precisely identify the sensitization to specific molecules of a given allergenic source, resulting in an important improvement in clinical management, particularly of polysensitized subjects. This will end in the correct prescription of allergen immunotherapy (AIT) for respiratory allergy and in adequate avoidance diets or prescription of self-injectable adrenaline in food allergy.

OBJECTIVE

The aim of this multicenter, real life study is to evaluate the percentage change of the diagnostic-therapeutic choice in polysensitized patients with respiratory allergy and in patients with food allergy, after using CRD compared to a first level diagnosis, along with an economic analysis of the patient's overall management according to the two different approaches.

METHODS

An overall number of 462 polysensitized patients, as suggested by skin prick tests (SPT), and with clinical symptoms related to a respiratory (275 pts) or food (187 pts) allergy, were recruited. All patients underwent CRD for specific IgE against food or inhalant recombinant molecules, which were chosen according to medical history and positivity to SPT. The first diagnostic-therapeutic hypothesis, based only on medical history and SPT, was recorded for each patient while the final diagnostic-therapeutic choice was based on the results from CRD. The rate of change of the diagnostic-therapeutic choice from the first hypothesis to the final choice was statistically evaluated. The economic impact of CRD on the overall management of the allergic patients was analyzed to evaluate whether the increase in the diagnostic costs would be compensated and eventually exceeded by savings coming from the improved diagnostic-therapeutic appropriateness.

RESULTS

An approximate 50% change (k index 0.54) in the prescription of AIT for respiratory allergy as well as a change in the prescription of self-injectable adrenaline (k index 0.56) was measured; an overall saving of financial resources along with a higher diagnostic-therapeutic appropriateness was also detected.

CONCLUSION

There is moderate agreement concerning prescription of AIT and self-injectable adrenaline before and after performing CRD: this highlights the usefulness of CRD, at least in polysensitized patients, in indicating the risk assessment and therefore the correct therapy of respiratory and food allergy, which results in a cost-saving approach.

An atlas of IgE sensitization patterns in different Italian areas. A multicenter, cross-sectional study

Summary

Background. The development of recombinant technology supported the allergy diagnostic work-up in the daily clinical practice, representing a useful tool for epidemiological studies. Methods. An atlas of the IgE sensitization profiles found throughout Italy was prepared from a nationwide, multicenter, cross-sectional study. Results. 6052 unselected consecutive individuals, belonging to North-West [NW], North-East [NE], Centre [C], South [S], and Islands subset [Is] were evaluated by means of the ImmunoCAP ISAC test. The top-ranked sensitizations found were Cup a 1 in [C] (58.1%) and [S] (53.6%), Phl p 1 in the North (from 46.1% to 49%), and Cyn d 1 in [Is] (44.2%). High frequency of house dust mite group 2 molecules sensitization was found in [C] (36.9%) and [S] Italy (40.8%), whilst low level of reactivity was recorded in [NW] (20%). Pellitory hypersensitivity was mainly found in [C], [S], and [Is], whilst ragweed Amb a 1 sensitivity was particularly found in [NW] Italy. IgE recognition of PR-10, Profilin, and nsLTP was mutually exclusive in 69.1% of cases, PR-10 reactivity mostly occurring in [NE], Profilin in [NW], and nsLTP molecules recognition mainly recorded in [C] and [S]. Conclusions. Divergent IgE sensitization patterns were found along Italy, possibly linked to the distinct geographical locations, indicating multiplex system IgE analysis as a reliable approach for epidemiological evaluation even in small geographical areas.

Storage molecules from tree nuts, seeds and legumes: relationships and amino acid identity among homologue molecules

Summary

The families of seed storage proteins, together with profilins, oil-bodies-associated oleosins, and pathogenesis-related (PR) proteins like PR-10 (Bet v 1-like), PR-12 (defensins) and PR-14 (non-specific lipid transfer protein), are the main causes of IgE sensitization to tree nuts, legumes and seeds. All these allergens, with the exclusion of profilins and of PR-10, are heat-stable and possibly responsible for fatal or almost fatal adverse reactions to such foods. In this short review, we will discuss the relationship and amino acid identities among some of the seed storage homologue molecules identified to date from tree nuts, seeds and legumes.

Definition of the upper reference limit for thyroglobulin antibodies according to the National Academy of Clinical Biochemistry guidelines: comparison of eleven different automated methods

Purpose

In the last two decades, thyroglobulin autoantibodies (TgAb) measurement has progressively switched from marker of thyroid autoimmunity to test associated with thyroglobulin (Tg) to verify the presence or absence of TgAb interference in the follow-up of patients with differentiated thyroid cancer. Of note, TgAb measurement is cumbersome: despite standardization against the International Reference Preparation MRC 65/93, several studies demonstrated high inter-method variability and wide variation in limits of detection and in reference intervals. Taking into account the above considerations, the main aim of the present study was the determination of TgAb upper reference limit (URL), according to the National Academy of Clinical Biochemistry guidelines, through the comparison of eleven commercial automated immunoassay platforms.

Methods

The sera of 120 healthy males, selected from a population survey in the province of Verona, Italy, were tested for TgAb concentration using eleven IMA applied on as many automated analyzers: AIA-2000 (AIA) and AIA-CL2400 (CL2), Tosoh Bioscience; Architect (ARC), Abbott Diagnostics; Advia Centaur XP (CEN) and Immulite 2000 XPi (IMM), Siemens Healthineers; Cobas 6000 (COB), Roche Diagnostics; Kryptor (KRY), Thermo Fisher Scientific BRAHMS, Liaison XL (LIA), Diasorin; Lumipulse G (LUM), Fujirebio; Maglumi 2000 Plus (MAG), Snibe and Phadia 250 (PHA), Phadia AB, Thermo Fisher Scientific. All assays were performed according to manufacturers’ instructions in six different laboratories in Friuli-Venezia Giulia and Veneto regions of Italy [Lab 1 (AIA), Lab 2 (CL2), Lab 3 (ARC, COB and LUM), Lab 4 (CEN, IMM, KRY and MAG), Lab 5 (LIA) and Lab 6 (PHA)]. Since TgAb values were not normally distributed, the experimental URL (e-URL) was established at 97.5 percentile according to the non-parametric method.

Results

TgAb e-URLs showed a significant inter-method variability. Considering the same method, e-URL was much lower than that suggested by manufacturers (m-URL), except for ARC and MAG. Correlation and linear regression were unsatisfactory. Consequently, the agreement between methods was poor, with significant bias in Bland–Altman plot.

Conclusions

Despite the efforts for harmonization, TgAb methods cannot be used interchangeably. Therefore, additional effort is required to improve analytical performance taking into consideration approved protocols and guidelines. Moreover, TgAb URL should be used with caution in the management of differentiated thyroid carcinoma patients since the presence and/or the degree of TgAb interference in Tg measurement has not yet been well defined.

Ara h 6 sensitization in peanut allergy: friend, foe or innocent bystander?

The clinical role of Ara h 6 sensitization in peanut allergy is a current matter of debate. We investigated the role of Ara h 6 sensitization patterns in a sample of young adults from different Italian cities. Sera of 33 patients with specific IgE against Ara h 6 were selected. According to clinical symptoms upon peanut ingestion, patients were divided into severe reaction (SR) and mild-tolerant (MT) subgroups. While the SR group mainly showed sensitization patterns involving Ara h 2 and other major allergenic components, a previously undescribed association between Ara h 6 and Ara h 9 was found in the MT group. This pattern seems to be clustered in Mediterranean Italy and associated with Pru p 3 sensitization. This finding might shed a new light on the role of Ara h 6 sensitization in peanut allergy.

Shrimp Allergy: Analysis of Commercially Available Extracts for In Vivo Diagnosis

BACKGROUND AND OBJECTIVE

Skin prick testing (SPT) with commercial extracts is the first step in the diagnosis of shrimp allergy, although its clinical efficiency is unknown. Objective: To analyze the clinical usefulness of all commercial crustacean extracts available for SPT in Italy.

METHODS

We performed a multicenter study of 157 shrimp-allergic patients who underwent SPT with 5 commercial crustacean extracts and with house dust mite (HDM) extract. Commercial extracts were analyzed using SDS-PAGE and compared with a freshly prepared in-house shrimp extract. IgE to Pen a 1/Pen m 1, Pen m 2, and Pen m 4 was determined, and immunoblot analysis was performed on a large number of sera.

RESULTS

The skin reactions caused by commercial crustacean extracts were extremely heterogeneous, resulting in 32 clinical profiles, with marked differences in protein content and missing proteins at molecular weights corresponding to those of major shrimp allergens. Only strong Pen a 1/Pen m 1 reactors reacted to both HDM and all 5 commercial extracts in SPT. Most patients, including those who were tropomyosin-negative, reacted to HDM. Patients reacted to a large and variable array of proteins, and IgE reactivity was common at high molecular weights (>50 kDa).

CONCLUSIONS

The in vivo diagnosis of shrimp allergy must continue to be based on SPT with fresh material. Shrimp-allergic patients frequently react to a number of ill-defined high-molecular-weight allergens, thus leaving currently available materials for component-resolved diagnosis largely insufficient. Mites and crustaceans probably share several allergens other than tropomyosin.

Unusual allergy to soy appeared in adult age

A case of adult onset severe soy allergy is discussed. The allergen protein involved did not correspond to those presently detectable by commercial diagnostic means, but was not identified, possibly due to the insufficient level of specific IgE. Fresh foods and commercial food extracts remain an invaluable tool to support the diagnosis of food allergy, both in-vivo and in-vitro.

Alpha-gal anaphylaxis: the first case report in Italy

We report the case of a 55-year-old man who went into anaphylactic shock six hours after eating a meal containing meat. He reported having had several tick bites in months before the reaction. The serum specific IgE showed strong positivity to alpha-gal. This is clearly alpha-gal anaphylaxis with delayed onset after meat ingestion caused by tick bite, confirmed by alpha-gal IgE positivity.

Shrimp allergy beyond Tropomyosin in Italy: clinical relevance of Arginine Kinase, Sarcoplasmic calcium binding protein and Hemocyanin

BACKGROUND

Little is known about the prevalence and clinical relevance of sensitization to shrimp allergens other than tropomyosin.

OBJECTIVE

We detected the prevalence of arginine kinase and sarcoplasmic calcium binding protein sensitization, and identified a high molecular weight allergen that is frequently recognized by Italian shrimp-allergic patients.

METHODS

Sera from 40 shrimp-allergic patients underwent the detection of IgE specific for arginine kinase (rPen m 2) and sarcoplasmic calcium-binding protein (rPen m 4) by ISAC 112 Microarray platform and immunoblot analysis. A high molecular weight shrimp allergen was identified by N-terminal amino acid sequencing.

RESULTS

IgE to rPen m 2 and rPen m 4 were found in 4/40 (10%) and 6/40 (15%) sera, respectively; two sera reacted to both allergens. Clinically, 6/8 Pen m 2 and/or Pen m 4 reactors experienced severe allergies to shrimp. On immunoblot, 4/6 rPen m 4-positive sera showed IgE reactivity at about 20 kDa, whereas no rPen m 2-positive serum reacted at about 40 kDa. Nineteen (47%) sera showed IgE reactivity at molecular weights > 60 kDa. Such profile was not associated with IgE reactivity to rPen m 2 or rPen m 4. N-terminal amino acid sequencing of the high molecular weight allergen led to the identification of hemocyanin.

CONCLUSION

Shrimp arginine kinase and sarcoplasmic calcium-binding protein are minor allergens sensitizing only 10%-15% of Italian shrimp-allergic patients, but are clinically relevant. Hemocyanin is a clinically relevant high molecular weight shrimp allergen possibly cross-reacting to house dust mite.

Component resolved diagnosis (CRD): how much is it presently used by Italian allergists?

Component resolved diagnosis (CRD) represents an innovative and revolutionary tool in allergy diagnosis. At the same time, some criticisms can be outlined. The present web survey aimed at investigating the role of CRD in daily clinical practice, according to a sample of Italian specialists who manage allergic patients. 127 physicians, mostly allergists, completed the questionnaire, mainly coming from North and Center of Italy. Most of them (80%) were allergists. One physician out of three regularly takes into consideration CRD, that is currently available about in a half of the hospitals where the specialists work. CRD is mostly prescribed in the diagnostic work-up of suspected food allergy, as it can drive risk assessment, epinephrine prescription and dietary advice. Concerning respiratory allergy, CRD is considered useful in investigating cross-reactivity and in defining the best treatment option, even if only 32% of patients treated with immunotherapy had been previously studied with CRD. The present survey points out the need for the specialists to develop a more practical know-how about CRD. Its diagnostic accuracy and its real impact on the clinical management need to be better defined. The lacking of CRD technology in many hospitals limits the possibility for many allergists to directly experience molecular diagnosis.

Heterogenity of IgE response to walnut and hazelnut in Italian allergic patients

BACKGROUND

The prevalence of IgE reactivity against genuine walnut and hazelnut allergens is poorly defined.

OBJECTIVE

The IgE response to walnut and hazelnut was investigated in Italian patients with primary allergy to these nuts.

METHODS

Sera from 36 patients allergic to hazelnut and/or walnut, not reactive to PR-10, profilin, and LTP, underwent immunoblot analysis with extracts of both nuts.

RESULTS

Most patients had a history of systemic symptoms following the ingestion of the offending food(s). Twelve patients were sensitized to both walnut and hazelnut, and 13 were sensitized to other nuts and seeds (cashew, peanut, sesame, pine nut, almond, Brazil nut, and pistachio). On walnut immunoblot, the 7 sera which scored positive showed much variability in their IgE profile. Two reacted uniquely at 10 kDa, and the others at 35 , 40, 45, 50, 67, and > 67 kDa. The profiles obtained under reducing and non-reducing conditions showed several differences. The 7 sera positive on hazelnut immunoblot under reducing conditions recognized sera at 10 kDa and at <10 kDa (n=1), 20 kDa (n=4), at about 22, 24, 30, 40, 43, 58, 60, and 90 kDa, and higher m.w. in other cases. Under non-reducing conditions IgE reactivity at 20, 28, 35, 40, 45, 60, 90, and 100 kDa, was detected. Only two sera scored positive under both conditions and showed an IgE profile that partly changed from one assay to another.

CONCLUSION

The current list of walnut and hazelnut allergens is far from being complete. Both reducing and non-reducing conditions are needed to detect IgE reactivity in individual patients.

Mugwort-fennel-allergy-syndrome associated with sensitization to an allergen homologous to Api g 5

BACKGROUND

The cross-reactive allergen responsible for the so called "mugwort-celery-spice-syndrome", a pollen-food allergy that occurs in a minority of mugwort pollen-allergic patients, is still undefined.

OBJECTIVE

To identify the allergen responsible for the cross-reactivity between mugwort pollen and plant-derived foods.

METHODS

The serum from one index patient with both fennel and mugwort pollen allergy was used to identify IgE-reactive allergens by direct ELISA and Immunoblot analysis. Cross-reactivity between mugwort pollen and fennel was checked by cross-inhibition experiments. Fennel and mugwort allergens selected on the basis of IgE reactivity and inhibition tests were excised from SDS-PAGE gels and microsequenced. The amino acid sequences obtained were used to screen the NCBI database using the protein BLAST software.

RESULTS

On ELISA inhibition experiments, serum absorption with fennel extract completely inhibited the IgE response to mugwort. On immmunoblot analysis periodate treatment caused the disappearance of all bands of IgE reactivity except one at about 60 kDa. The 60 kDa bands from both mugwort and fennel PAGE-SDS gels revealed the presence of distinct proteins. The N-terminal amino acid sequencing gave the same major amino acid sequence corresponding to an Api g 5-like allergen. The MS/MS spectra were analyzed and a provided evidence of a fennel-specific protein with sequence similarity to phosphoglyceromutase from Apium graveolens.

CONCLUSION

A 60 kDa allergen, highly homologous to Api g 5, was recognized in fennel by patient's IgE. Inhibition experiments showed a high degree of cross-reactivity between this fennel allergen and the homologous mugwort pollen allergen. This allergen might be responsible for the mugwort-celery-spice syndrome.

Polarization of TH2 response is decreased during pregnancy in systemic lupus erythematosus

This study evaluated some cytokines involved in the Th1-Th2 shift during pregnancy in patients with systemic lupus erythematosus (SLE) and healthy women. Twenty-seven consecutive successful pregnancies in 26 SLE patients and 28 pregnancies in 28 matched healthy subjects, as controls, were enrolled and prospectively studied. Sera obtained at first and third trimesters of pregnancy were tested for IL-1α, IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, INF-γ, and TNF-α with a highly sensitive, multiplexed sandwich ELISA (SearchLight Human Inflammatory Cytokine Array). Statistics were performed by SPSS package. IL-8 serum levels were higher in the first (P&lt;0.0001) and third (P=0.003) trimesters of pregnancy in SLE patients compared with controls, INF-γ serum levels in the third trimester (P=0.009), and IL-10 serum levels in the first and third trimesters (P=0.055 and P&lt;0.0001, respectively). IL-2 (r=0.524 P=0.010), IL-12 (r=0.549 P=0.007), IFN-γ (r=0.492 P=0.017), and IL-6 (r=0.515 P=0.020) serum levels correlated with disease activity in SLE patients in the first trimester of pregnancy. Cytokine profile was similar in patients with and without lupus nephritis both in the first and in the third trimesters of pregnancy. IL-8 serum levels were lower in patients with a previous diagnosis of antiphospholipid antibody syndrome compared with those without, both in the first and in the third trimesters of pregnancy. In SLE patients, a lower than expected decrease in Th1 cytokine serum levels was observed in the third trimester of gestation which could contribute to a lower Th2 cytokine polarization during pregnancy.

A case of rice allergy in a patient with baker's asthma

A case of rice allergy in a patient with bakers asthma is described. On ISAC 112 IgE reactivity to wheat alpha-amylase/trypsin inhibitor (nTri a aA_TI) and lipid tranfer protein (rTri a 14) was found. We hypothesize that the reaction by oral ingestion was elicited by homologous molecules in rice seeds.

Monosensitization to a novel plane pollen allergen

A patient monosensitized to plane pollen is described On ISAC 103 the patients showed IgE reactivity to both Pla a 1 and Pla a 2, but on immunoblot analysis the serum showed a single IgE reactivity at about 50 kDa allergen.

Are anti-Phl p 12 IgE levels predictive of oral allergy syndrome in profilin hypersensitive patients?

BACKGROUND

In birch pollen-allergic patients the occurrence of clinically relevant crossreactivity to plant-derived foods is clearly related with the level of birch-specific IgE. In profilin-hypersensitive patients this has not been investigated so far.

OBJECTIVE

To investigate whether the levels of profilin IgE are predictive of the development of food allergy in hypersensitive patients.

METHODS

IgE specific for Phl p 12, the grass pollen profilin, were measured in 37 subjects monosensitized to profilin with (n = 11) or without (n = 26) oral allergy syndrome (OAS) following the ingestion of plant-derived foods.

RESULTS

Patients without a history of OAS showed higher levels of IgE specific for Phl p 12 than patients with OAS (median 4.74 [range 0.7-41.6] KU/L vs 2.14 [range 0.32-10.2] KU/L, respectively) although the difference did not reach statistical significance (p = 0.07).

CONCLUSION

Factors causing the onset of OAS in profilin-hypersensitive patients remain presently unclear.

Shrimp allergy in Italian adults: a multicenter study showing a high prevalence of sensitivity to novel high molecular weight allergens

BACKGROUND

Shrimp is a frequent cause of food allergy worldwide. Besides tropomyosin, several allergens have been described recently.

OBJECTIVE

We investigated which allergens are involved in Italian shrimp-allergic adults.

METHODS

Sera from 116 shrimp-allergic patients selected in 14 Italian allergy centers were studied. Skin prick tests with house dust mite (HDM) as well as measurements of IgE to Pen a 1 (shrimp tropomyosin) and whole shrimp extract were performed. All sera underwent shrimp immunoblot analysis, and inhibition experiments using HDM extract as inhibitor were carried out on some Pen a 1-negative sera.

RESULTS

Immunoblots showed much variability. IgE reactivity at about 30 kDa (tropomyosin) was found in <50% of cases, and reactivity at about 67 kDa and >90 kDa was frequent. Further reactivities at 14-18, 25, 43-50, about 60 and about 80 kDa were detected. Most subjects had a history of shrimp-induced systemic symptoms irrespective of the relevant allergen protein. IgE to Pen a 1 were detected in sera from 46 (41%) patients. Skin reactivity to HDM was found in 43/61 (70%) Pen 1-negative subjects and inhibition studies showed that pre-adsorption of sera with HDM extract induced a marked weakening of the signal at >67 kDa.

CONCLUSIONS

Several allergens other than tropomyosin are involved in shrimp allergy in adult Italian patients. Some hitherto not described high molecular weight allergens seem particularly relevant in this population and their cross-reactivity with HDM allergens makes them novel potential panallergens of invertebrates.

Analysis of the allergenic profile of patients hypersensitive to pollen pan-allergens living in two distinct areas of northern Italy

BACKGROUND

The allergenic profile of patients hypersensitive to pollen pan-allergens, profilin and polcalcin, has received little attention so far.

OBJECTIVE

To detect whether hypersensitivity to profilin and polcalcin follows sensitization to specific allergen sources or represents a primary phenomenon, and to examine the sensitization profiles of patients hypersensitive to pollen pan-allergens.

METHODS

IgE reactivity to markers of primary sensitisation to different pollen species including grass, mugwort, ragweed, pellitory, birch, olive, and cypress was detected in sera from 106 pollen-allergic subjects, 86 sensitised to profilin and 29 to polcalcin living in two distinct areas of Northern Italy.

RESULTS

In profilin hypersensitive patients the primary sensitizer was detected in 24/86 (28%) cases: grass (n=15), ragweed (n=7), and birch (n=2). In 62 (72%) cases the primary sensitizing pollen was not detectable. In the polcalcin group the primary sensitizing pollen was detected in 8/29 (28%) cases: grass (n=6), ragweed and pellitory (1 each). All ragweed-allergic subjects were from the Milan area. In the 9 patients hypersensitive to both panallergens the primary sensitizing source could be identified in 2 (23%) cases (grass in both cases).

CONCLUSION

A putative primary sensitizer to pollen pan-allergens can be detected only in 1/4 of cases, as most patients show IgE specific for >1 pollen species. In these patients the prevalence of the primary sensitizer parallels the prevalence of clinical allergy to the different pollen sources in that specific geographic area. Most pollen sources are probably able to cause sensitization to cross-reacting pollen pan-allergens.

Thyrotropin receptor autoantibody measurement following radiometabolic treatment of hyperthyroidism: comparison between different methods

BACKGROUND

TSH receptor antibodies (TRAb) play a crucial role in the pathogenesis of Graves' disease (GD). The use of human recombinant TSH-receptor far improved the analytical performance of TRAb assays (2nd-generation assays). The 3rd-generation assay is based on the inhibition of binding of a human biotin-labeled monoclonal thyroid- stimulating antibody (M22) to TSH-receptor by the autoantibodies present in the serum.

AIM

We aimed to assess the ability of the 2nd- and 3rd-generation assays to detect serum TRAb following radioiodine therapy for hyperthyroidism.

METHODS

Sera from 47 hyperthyroid (25 autoimmune, 22 non-autoimmune) patients were tested using the two different assays before and at different time intervals after radioiodine therapy. The modifications of TRAb were evaluated, as well as the correlation between the two methods.

RESULTS

The results obtained by the two methods proved to be closely correlated. A rise in TRAb was invariably observed in GD patients following radioiodine, with a median peak at 6 months, irrespective of their initial clinical status, presence of ophthalmopathy, smoking habits or other variables. Such a rise was nearly superimposable using both methods. No TRAb appearance was observed in patients with non-autoimmune hyperthyroidism.

CONCLUSIONS

The use of methods of higher sensitivity with respect to that formerly used indicate that nearly all GD patients develop TRAb following radioiodine, and that this phenomenon is transient and not related to baseline conditions and clinical outcome/efficacy of treatment.

Diagnosing systemic lupus erythematosus: new-generation immunoassays for measurement of anti-dsDNA antibodies are an effective alternative to the Farr technique and the Crithidia luciliae immunofluorescence test

The aim of this study was to evaluate the diagnostic performance of four new enzyme immunoassays (EIAs) for anti-double-stranded-DNA (anti-dsDNA) antibodies, in comparison with the Farr assay and the Crithidia luciliae immunofluorescence test (CLIFT). To this purpose, sera from four patient groups were collected: 52 sera from patients with systemic lupus erythematosus (SLE); 28 from patients with other connective tissue diseases (CTD); 36 from patients with hepatitis C virus (HCV) infection; and 24 from those with acute viral infection. All sera were tested for anti-dsDNA antibodies by four EIA methods using a different antigenic DNA source [synthetic oligonucleotide (Method A), circular plasmid (Method B), recombinant (Method C), and purified extracted (Method D)], and by CLIFT and Farr assays. The diagnostic sensitivity of the assays was as follows: 84.6% (Method A), 73% (B), 82.7% (C), 84.6% (D), 55.8% (CLIFT), and 78.8% (Farr). Specificity was 82.9% (A), 97.7% (B), 96.5% (C), 94.3% (D), 96.5% (CLIFT), and 90.9% (Farr). From these data, we can conclude that the new-generation EIA methods evaluated in this study have higher sensitivity than the CLIFT and Farr assays and, with the exception of Method A, have specificity similar to the CLIFT and slightly higher than the Farr assay. These findings suggest that EIA tests may replace CLIFT as a screening test and the Farr assay as a specific test, for anti-dsDNA antibody detection.

Detection of a novel 20 kDa shrimp allergen showing cross-reactivity to house dust mites

BACKGROUND

Allergy to crustacean shellfish is one of the most common IgE-mediated food allergies, and tropomyosin has been identified as the major allergen. However, not all subjects affected by this allergy are IgE-positive to tropomyosin.

AIMS

To evaluate whether sera of patients with shrimp allergy but negative for tropomyosin react to other allergen(s); and to evaluate the role such allergen(s) may play in cross-reactivity between crustaceans and house dust mites (HDMs).

METHODS

Three different pools of sera-one from subjects with shellfish allergy and HDMs positivity, but negative for recombinant and native tropomyosin (rPen a 1 and nPen m 1) (Pool 2); a second from subjects with tropomyosin and HDMs positivity (Pool 1); and the last from subjects allergic only to HDMs (Pool 3) were submitted to immunoblotting. Subsequently, a 20 kDa protein- enriched fraction of shrimp extract was used at two different concentrations (10 and 100 microg/mL) to pre-absorb the Pool 2 serum and to evaluate, by ELISA assay, the level of inhibition on shrimp and HDMs-coated wells, respectively.

RESULTS

The Pool 2 serum showed IgE reactivity against a 20 kDa component. Its pre-absorption with an enriched fraction of 20 kDa protein caused an inhibition of 56% in IgE binding to shrimp extract at a concentration of 100 microg/mL, and of 14% and 35% to HDMs extract at concentrations of 10 and 100 microg/mL, respectively, as measured by ELISA assay.

CONCLUSIONS

The 20 kDa component seems to be a new crustacean allergen and it could play a role in cross-reactivity with HDMs.

Sensitization to the pollen pan-allergen profilin. Is the detection of immunoglobulin E to multiple homologous proteins from different sources clinically useful?

BACKGROUND

Profilin is a highly conserved protein regarded as a pan-allergen in pollen and vegetable food. Homologous proteins from different sources are highly cross-reactive.

OBJECTIVE

To assess whether detecting immunoglobulin (Ig) E to multiple profilins from different sources is clinically more useful than detecting IgE to a single representative profilin.

METHODS

Sera from 43 subjects sensitized to profilin selected in 2 allergy centers in Northern Italy showing a different pollen exposure profile were studied for their IgE reactivity to 5 profilins (Bet v 2, Ole e 2, Hev b 8, Mer a 1, and Phl p 12) using a commercial allergen microarray immunoassay.

RESULTS

All 43 patients (100%) scored positive to at least 1 profilin on ISAC, although reactivity to all 5 profilins was observed in only 37 cases (86%). In approximately half of the reactors, IgE reactivity to Ole e 2 was much weaker than that to other profilins irrespective of the primary sensitizing allergen source, suggesting a low sensitivity of this allergen. Much discrepancy in IgE to Bet v 2 measured by ISAC microarray and ImmunoCAP was observed.

CONCLUSION

Detecting IgE reactivity to a single marker protein (eg, Bet v 2) is sufficient to diagnose or exclude sensitization to profilin. Detecting IgE to multiple homologous, cross-reacting allergen proteins is not clinically more informative and increases the risk of confusion and misinterpretation.

Eosinophilic esophagitis: from the case report to the evidence

Eosinophilic esophagitis (EE) is a rare disease characterized by esophageal symptoms and dense esophageal eosinophilic infiltrate, both of wich persist despite prolonged treatment with proton pump inhibitors. The pathogenesis is poorly understood, but there is an increasing body of clinical and basic evidence that EE is an immune-mediated disease triggered by both food and inhalant allergens. At present there is no consensus statement on the number of eosinophils requiredfor the diagnosis, but generally a number of 20 eosinophils per high power field is considered a significant cut-off point. Therapies considered to be effective in the treatment of EE include: specific elimination diets or elemental diets; either systemic or topical corticosteroids therapy; and therapy with a selective inhibitor of leukotriene D4 receptor.

Recent advances in diagnostic technology: applications in autoimmune and infectious diseases

Biomarkers are used ubiquitously as indicators of biological health. The development of genomic and proteomic multiplex technologies have enormously amplified biomarker discovery and application to diagnostic and therapeutic decisions in clinical practice. New technologies are now available that simultaneously identify a wide spectrum of biomarkers and save time and costs. Multiplexed assays can be coupled to other disease specific indicators (i.e., cytokines, single nucleotide polymorphisms) in order to get more powerful information. However, there is an urgent need for validation/standardization of the new assays before they are adopted into clinical diagnostics. It is worthy to note a new assay, T cell interferon gamma release (TIGRAs), which has recently been introduced in the diagnosis of latent tuberculosis infection. It seems to perform better than tuberculin skin test in patients with inflammatory rheumatic diseases. In this review, we focus on advantages and limits of novel approaches to the detection of autoantibody profiles in autoimmune diseases or pathogen signatures in microbiology.

Diagnostic accuracy of IgA anti-tissue transglutaminase antibody assays in celiac disease patients with selective IgA deficiency

Clinical studies have estimated a 10- to 20-fold increased risk for celiac disease (CD) in patients with selective IgA deficiency (SIgAD). For this reason, screening for CD is mandatory in SIgAD patients, but it represents a special challenge since the specific IgA class antibodies against gliadin (AGA), endomysium (EMA), and tissue-transglutaminase (tTG) are not produced in patients with CD. IgG class counterparts of these antibodies may be informative; in particular IgG EMA has been demonstrated to be a valid marker for diagnosing CD in SIgAD cases, but it is not used much in clinical laboratories, because it is cumbersome and involves some technical difficulties. Even if it was widely used in clinical laboratories, the measuring of IgG AGA has shown a less-than-optimum diagnostic accuracy, so that now it tends to be substituted by tests for anti-tTG IgG, for which the few available studies have shown diagnostic performances superior to AGA. Since it is not known whether various available methods for measuring IgG anti-tTG antibodies offer similar diagnostic performances, we have compared the results obtained from nine second-generation commercial methods (D-tek, Phadia, Immco, Orgentec, Radim, Euroimmun, Inova, Aesku, Generic Assays), measuring IgG anti-tTG antibodies in 20 patients with CD and SIgAD and in 113 controls (9 patients with SIgAD without CD, 54 patients with chronic liver disease, and 50 healthy individuals). Diagnostic sensitivity, calculated by means of ROC plot analysis, ranged between 75% and 95%, and specificity ranged from 94% to 100%. In the same population, the diagnostic sensitivity and specificity of AGA IgG were 40% and 87%, respectively. Even though they perform differently, all IgG anti-tTG methods evaluated are reliable serological assays for the diagnosis of CD in SIgAD patients, with diagnostic accuracy superior to the AGA IgG method. The methods that use a mix of tTG and gliadin peptides as the antigenic preparation have a specificity slightly lower than that of the methods that use only tTG.

Anti-prothrombin antibodies predict thrombosis in patients with systemic lupus erythematosus: a 15-year longitudinal study

OBJECTIVE

To evaluate the role of anti-prothrombin (anti-PT) antibodies in predicting thrombosis in patients with systemic lupus erythematosus (SLE).

METHODS

An inception cohort of 101 SLE patients (12 males, 89 females; mean age 30 +/- 8 years), was considered. Clinical and laboratory evaluations were regularly performed during a 15-year follow-up (median 108 months) with a special focus on thromboembolic events. Serum samples were collected at time of diagnosis and at least once a year thereafter. IgG and IgM anti-PT, anti-cardiolipin (aCL) and anti-beta(2)glycoprotein I (beta(2)GPI) antibodies were measured by enzyme-linked immunosorbent assay (ELISA); lupus anticoagulant (LAC) was assayed by the dilute Russell's viper venom time and activated partial thromboplastin time tests. The analytical specificity of anti-PT ELISA was investigated. The timing of thrombosis occurrence was calculated using the Kaplan-Meier method.

RESULTS

In the 15-year follow-up, thrombosis occurred in 14 out of the 101 patients: venous thrombosis in nine cases and arterial thrombosis in five. IgG and/or IgM anti-PT, anti-beta(2)GPI and aCL antibodies, and LAC activity were detected in ten, nine, seven, and nine cases, with sensitivity for thrombosis of 71.4%, 64.3%, 50% and 64.3%, respectively. Thrombosis-free survival was 90% at 5 years and 85.8% at 10 and 15 years, respectively. Thrombosis was predicted by anti-PT (P = 0.001), anti-beta(2)GPI antibodies (P = 0.002) and LAC activity (P = 0.001). Moreover, the risk of thrombosis progressively increased with the number of positive antiphospholipid antibody tests. The presence of four positive antibody tests was associated with a risk of thrombosis thirtyfold higher than in their absence.

CONCLUSIONS

This longitudinal study shows that IgG anti-PT antibodies are predictors of thrombosis in SLE patients.

Antiprothrombin antibodies: a comparative analysis of homemade and commercial methods. A collaborative study by the Forum Interdisciplinare per la Ricerca nelle Malattie Autoimmuni (FIRMA)

OBJECTIVE

Prothrombin (PT) is a target for antibodies with lupus anticoagulant (LA) activity, suggesting the possible application of anti-prothrombin antibody (aPT) assays in patients with antiphospholipid syndrome (APS). Different methods - both homemade and commercial - for the detection of aPT are available, but they seem to produce conflicting results. The purpose of this study was to compare the performance of different assays on a set of well-characterized serum samples.

PATIENTS AND METHODS

Sera were gathered from 4 FIRMA institutions, and distributed to 15 participating centres. Forty-five samples were from patients positive for LA and/or anticardiolipin antibodies (aCL) with or without APS, and 15 were from rheumatoid arthritis (RA) patients negative for antiphospholipid antibodies. The samples were evaluated for IgG and IgM antibodies using a homemade direct aPT assay (method 1), a homemade phosphatidylserine-dependent aPT assay (aPS/PT, method 2), and two different commercial kits (methods 3 and 4). In addition, a commercial kit for the detection of IgG-A-M aPT (method 5) was used.

RESULTS

Inter-laboratory results for the 5 methods were not always comparable when different methods were used. Good inter-assay concordance was found for IgG antibodies evaluated using methods 1, 3, and 4 (Cohen k > 0.4), while the IgM results were discordant between assays. In patients with thrombosis and pregnancy losses, method 5 performed better than the others.

CONCLUSION

While aPT and aPS/PT assays could be of interest from a clinical perspective, their routine performance cannot yet be recommended because of problems connected with the reproducibility and interpretation of the results.

Low specificity of anti-tissue transglutaminase antibodies in patients with primary biliary cirrhosis

The association between celiac disease (CD) and primary biliary cirrhosis (PBC) is well documented in medical literature; however, a high frequency of false positive results of the anti-transglutaminase (anti-tTG) test has been reported in patients with PBC. To verify if the positive results for anti-tTG autoantibody are false positives due to cross reactivity with mitochondrial antigens, we studied 105 adult patients affected with PBC, positive for anti-mitochondrial M2 antibodies. Anti-tTG IgA antibodies were studied by using six different immunoenzymatic assays that employ the tTG antigen obtained from different sources (human recombinant, placenta, red blood cells, and guinea pig liver). On the whole, 28 out of 105 PBC subjects tested positive for anti-tTG IgA antibodies, but only two were eventually found to be affected by CD; the other 26 were shown to be false positive. The specificity of the various antigenic substrates ranged from 88.5% of the human erythrocytes tTG to 97.1% of the human recombinant tTG. The results of this study showed that a true association between PBC and CD was present in only 2% of the patients and that, in most cases, the false positive results were attributable to the type of substrate utilized in the assay.

A Prospective Study of 1038 Pregnancies on the Predictive Value of Anti-Annexin V Antibodies for Fetal Loss

Retrospective studies have demonstrated that anti-annexin V (anti-AnxV) antibodies are linked to miscarriage. Their predictive value is, however, unknown. We have carried out a prospective study to evaluate the relationship between anti-AnxV antibodies and the pregnancy outcome. A serum sample was taken from 1038 consecutive healthy women at the beginning of pregnancy. IgG and IgM anti-AnxV antibodies were measured by an ELISA method. The cutoff value was set at 5 units for both IgG and IgM. Out of 1038 women, 116 (11.4%) had a miscarriage by the 22nd week; 10 were lost to follow-up, 10 had an induced abortion, 6 had a preterm delivery, and 896 carried their pregnancy through to term. An adverse outcome of the pregnancy proved to be directly related to the number of previous miscarriages (P = .008) and the age of the woman (P = .002). IgG and IgM anti-AnxV were present in 25% and 27% of the women who miscarried, and in 23% and 28% of those who gave birth (mean antibody concentration IgG, 4.2 vs. 4.4 U/mL; IgM, 3.7 vs. 3.5 U/mL). IgG and IgM anticardiolipin and anti-beta(2)GPI, together with antinuclear, antithyroperoxidase, and antithyroglobulin antibodies, were also measured in the 116 sera of the women with miscarriage and in an equal number of women who gave birth. Their positivity or level proved not to be useful in discriminating between the risk of miscarriage and term delivery. This large-scale prospective study demonstrates that the presence of IgG and IgM anti-AnxV antibodies, when measured in healthy women, does not give a positive predictive lead towards the possibility of a miscarriage, and it is not useful in evaluating the risk of miscarriage at the beginning of pregnancy.

Accuracy of semiquantitative immunoenzymatic methods in quantitation of anti-topoisomerase I (Scl-70) antibodies

Reports of a possible correlation between anti-Scl-70 antibody concentration and clinical manifestations in systemic sclerosis patients have recently appeared in the scientific literature. The goal of our study was to evaluate, by means of a multicenter study, the analytical reliability of immunoassay systems in the quantitative measurement of Scl-70 antibodies. Three blind samples (H, M, L) at different anti-Scl-70 antibody concentrations, and a low concentration antibody serum (LPC) used as a common calibrator, were sent three times in a 6-month time span to 39 Italian clinical laboratories. Each laboratory was asked to calculate dosages following the enzyme-linked immunosorbent assay (ELISA) method they used and report the optical density values of each sample (ODs), of the cutoff serum provided by the manufacturer of the kit used (ODco) and of LPC (ODLPC). The overall analytical imprecision (between methods and between laboratories) of the three different determinations of the values respectively expressed in ODs, ODs/ODco and ODs/ODLPCratio was 47.1, 52.8 and 34.0% for sample H, 56.2, 47.4% and 34% for sample M and 84.6, 86.0 and 86.6% for sample L. The average intra-method analytical imprecision was, respectively, 20.7, 29.8 and 18.6% for sample H, 24.6, 26.5 and 19.3% for sample M, and 30.6, 28.1 and 20.2% for sample L. The commercial ELISA methods currently used to determine the presence of anti-Scl-70 autoantibodies show considerable differences in the quantitative determination. The best results for reproducibility analyses have been obtained when the values were expressed as a ratio between the ODs of the sample and of the common calibrator (ODs/ODLPC). Forward-looking clinical studies that can clarify the usefulness of quantitative determination of anti-Scl-70 antibodies in the monitoring of diffuse scleroderma patients can be performed only when standard serum with a known antibody concentration and calibration curves for quantitative ELISA measurements are made available.