Uncovering a Severe Patient Group With Pollen-Related Extrarespiratory Allergic Symptoms: A Year-Long Diary Survey in Japan.

BACKGROUND: The most common symptoms of pollen allergy are rhinitis and conjunctivitis. However, in real-world clinical practice, we sometimes encounter patients with pollen allergy suffering from severe extrarespiratory symptoms including skin, gastrointestinal, or flu-like symptoms in relation to exposure to sensitized pollen. OBJECTIVE: To elucidate the extrarespiratory symptoms in patients with pollen allergy. METHODS: We performed a non-drug-focused prospective study of patients with pollen allergy (n = 384). During the 1-year observational period, they were asked to complete a weekly electronic diary consisting of visual analog scale (VAS) scores to assess all symptoms experienced in various organs over the past week. An association between seasonal pollen levels and seasonal increase in VAS scores was evaluated using a mixed-effects model for repeated measures. A k-means cluster analysis was performed to identify a group of patients experiencing stronger extrarespiratory symptoms. RESULTS: In patients sensitized to grass or birch pollen, higher seasonal levels of these pollen grains were associated with higher VAS scores for headache, gastrointestinal symptoms, skin symptoms, and fatigue. A cluster analysis identified a group of severe pollen-allergic patients with higher extrarespiratory symptoms (n = 42). This group was characterized by a higher frequency of comorbid food allergy/atopic dermatitis, higher rate of IgE sensitization to pollens, and higher impaired activity and work productivity. CONCLUSIONS: This 1-year survey identified a small but nonnegligible group of patients with pollen-related extrarespiratory symptoms. More attention should be paid to this patient group considering their impaired activity and work productivity.

Identification of fungi causing humidifier lung: 2 rare cases and a review of the literature.

Background: Humidifier lung (HL) is a hypersensitivity pneumonitis resulting from exposure to humidifiers, with fungi from the humidifier as one of the etiologic agents. However, identification of the fungal species responsible for each case can be challenging because of difficulties in culturing fungi, their accurate identification, and interpreting the results of specific serum IgG testing. Objective: To clarify the best way to determine the causative fungal species of each HL case. Methods: We report 2 cases with HL in which rare fungi were identified as causative agents. In addition, we searched MEDLINE for previous publications on HL caused by fungi and performed a literature review focusing on clinical testing for the determination of causal fungal species. Results: In our 2 cases, we identified Fusarium oxysporum species complex, Purpureocillium lilacinum, Acremonium sclerotigenum/egyptiacum as the causative fungal species, based on findings that these could be cultured from humidifier water (HW) and precipitins against these fungi were also positive. The literature review identified 31 HL cases in which the causative fungal species had been documented. In more than half of the cases (17 of 31) there was a concordance between the fungal species cultured from HW and the presence of specific IgG in the blood. Conclusion: We recommend performing culture of fungi from HW and specific serum IgG testing for the accurate determination of the causative fungal species in HL, and concordance between them serves as a rationale for the determination of causative fungal species.

Clinical cross-reactivity of wheat and barley in children with wheat allergy.

BACKGROUND: Several studies have reported in vitro cross-reactivity between wheat and barley. However, evidence regarding the clinical cross-reactivity of wheat and barley is limited. This study examined the clinical cross-reactivity of barley and wheat among children with immediate-type wheat allergies. METHODS: We examined the threshold dose of a wheat oral food challenge for wheat-allergic children. We examined the reactivity of barley, and the oral food challenges of barley tea and barley rice were implemented as needed. We measured the specific immunoglobulin E (sIgE) levels in wheat, ω-5 gliadin, and barley. RESULTS: We evaluated 53 children (39 [74%] boys) with a median age of 6.6 years. Among them, 39 (74%) patients had a history of anaphylaxis to wheat. The median wheat-, barley-, and ω-5 gliadin-sIgE levels were 57.3, 12.1, and 3.2 kUA /L, respectively. Twelve patients reacted to barley tea (1.8 mg), 14 reacted to barley rice (220-440 mg), and 27 were tolerant to barley tea and barley rice. Barley-allergic patients had significantly higher wheat- and ω-5 gliadin- and barley-sIgE levels and significantly lower threshold doses of wheat than barley-tolerant patients. Omega-5 gliadin-sIgE was the most useful predictor of barley allergy among wheat-allergic patients; the ω-5 gliadin-sIgE 95% positive predictive value for barley allergy was 4.6 kUA /L. CONCLUSIONS: Half of wheat-allergic children reacted to barley. A lower threshold dose of wheat is related to cross-reactive barley allergies. Omega-5 gliadin-sIgE predicts cross-reactive barley allergy in children allergic to wheat. Clinical cross-reactivity to barley should be considered in the management of wheat-allergic children.

Cross-reactivity of each fraction among cereals in children with wheat allergy.

BACKGROUND: Cross-reactivity between wheat and other cereals is a crucial issue in the management of wheat allergy. Few studies have reported in vitro cross-reactivity in immediate-type wheat allergy. The aim of this study aimed to examine cross-reactivity of the three fractions (albumin/globulin, gliadin, and glutenin fractions) among cereals in children with wheat allergy. METHODS: Sera from 128 children with immediate-type wheat allergy were collected. Specific immunoglobulin E (sIgE) levels against each fraction of wheat, barley, and rye were measured by enzyme-linked immunosorbent assay (ELISA). Cross-reactivities of each fraction among wheat, barley, and rye were examined via inhibition ELISA. RESULTS: All subjects were sensitized to all fractions of wheat, barley, and rye. The wheat sIgE levels were significantly higher than those of barley and rye in all the fractions (p ≤ .001) and were significantly correlated with sIgE levels in each fraction (r = .887-.969, p < .001). Inhibition ELISA revealed that wheat inhibited the IgE binding to most of the solid phases at lower protein levels compared with barley and rye in all fractions. CONCLUSIONS: In children with immediate-type wheat allergy, sensitization to all the three fractions of wheat was observed. In addition, they showed sensitization to barley and rye caused by in vitro cross-reactivity with wheat in each fraction. When managing children with wheat allergy, sensitization to barley and rye caused by the cross-reactivities should be considered.

Optimal Aspergillus fumigatus and Asp f 1 serum IgG cut-offs for the diagnosis of allergic bronchopulmonary aspergillosis.

BACKGROUND: The presence of IgG antibodies (Abs) to Aspergillus fumigatus (Af) is a crucial diagnostic criterion for allergic bronchopulmonary aspergillosis (ABPA). Although precipitation is traditionally used to document IgG Abs, anti-Af serum IgG levels can also be measured by enzyme immunoassay (EIA). However, there are insufficient data on the optimal cut-offs to assess diagnostic performance of the EIA method. This study aimed to determine cut-off levels of IgG binding crude Af extracts or recombinant Asp f 1 (by ImmunoCAP®) and to compare their efficacy for ABPA diagnosis with Af-precipitating Abs. METHODS: The age distribution of levels of IgG to crude extracts of Af (Af-IgG) and recombinant Asp f 1 (Asp f 1-IgG) was established using sera from 694 healthy controls (HC). Receiver operating characteristic analysis for Af-IgG and Asp f 1-IgG levels for the purpose of ABPA diagnosis was performed in 306 Af-sensitized asthma patients (including 49 ABPA), and cut-offs were determined. RESULTS: An age-dependent decline in the levels of Af-IgG was observed in HC. Thus, cut-offs for Af-IgG levels were determined separately by age as 60 mg/L for patients aged <55 years, and 45 mg/L for those aged ≥55 years. For Asp f 1-IgG, 6.6 mg/L was set as the cut-off regardless of age. Although such IgG testing by EIA allowed a sufficiently good diagnostic performance, Af-precipitating Abs had better diagnostic applicability for ABPA. CONCLUSIONS: We determined cut-offs for Af-IgG and Asp f 1-IgG measured by EIA, which can be useful in clinical settings where precipitating Abs are unavailable.

[LONG-TERM RESULTS OF AIRBORNE POLLEN SURVEYS IN THE JAPANESE ARCHIPELAGO FROM THE PERSPECTIVE OF POLLEN ANTIGEN].

BACKGROUND: In 1986, the Ministry of Health and Welfare started an airborne pollen survey as part of measures against JC pollinosis. We reported the important tree pollen antigens in 2016. We have now estimated the longitudinal investigated results for successful prevention and treatment for allergic symptoms related to grass and weed pollen in Japan. METHOD: Since July 1986 we have monitored airborne pollen, year- round, using a gravitational pollen sampler (Durham's sampler), at more than 20 locations across Japan. Specimens were mailed to our facility, where they were stained with Calberla solution, counted under an optical microscope, and converted to the number of pollen per square centimeter. For convenience the number of collected pollen were compiled every six months, with the January to June samples classified as spring pollen and the July to December as autumn pollen even same family. RESULT: Total pollen counts at each location were extremely small compared to tree-pollen, averaging 73~650 pollen grains per year. The Sagamihara location had the greatest count. Unlike cedar and cypress there were no significant annual fluctuations, but grass and Ambrosia pollen counts are increasing in some regions. Spring grass pollen gave the largest count, at 30% of the total collected. CONCLUSION: This indicated we need to examine the rinoconjuctivitis and oral allergy syndrome related to herbaceous pollen carefully.The importance of airborne pollen surveys for the treatment of the patients with pollen allergies was suggested.

Concordance between Aspergillus-specific precipitating antibody and IgG in allergic bronchopulmonary aspergillosis.

BACKGROUND: Several serological tests for specific precipitin or IgG are available to demonstrate type III hypersensitivity reactions to Aspergillus species and are essential for infectious fungal disease diagnosis. These assays are also important for allergic bronchopulmonary aspergillosis (ABPA) diagnosis; however, their concordance in ABPA was not well studied. METHODS: Fifty-two ABPA patients diagnosed based on ISHAM criteria were enrolled. Precipitins and IgG specific to Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, or Aspergillus terreus were measured using Ouchterlony double immunodiffusion tests and ImmunoCAP method, respectively. A. fumigatus-specific IgG was also determined using complement-fixation (CF) method. RESULTS: Forty-eight percent of cases were double-positive for A. fumigatus-specific precipitin and IgG (ImmunoCAP), whereas 3 (6%) and 14 (28%) cases were positive for precipitin or IgG alone, respectively. Kappa coefficient between these measurements was 0.32, suggesting poor concordance. Double-positive cases were more likely to present: Aspergillus sp. in sputum culture, lower pulmonary functions, peripheral blood eosinophilia, higher total IgE and A. fumigatus-specific IgG titer than precipitin-negative cases. A. fumigatus-specific IgG (CF) was positive only in 8 (15%) cases. The presence of A. fumigatus-specific precipitin or IgG was associated with antibodies specific for other Aspergillus spp., suggesting cross-reactivity. CONCLUSIONS: Positive rate of A. fumigatus-specific precipitin or IgG (ImmunoCAP) was superior to IgG (CF), but relatively poor concordance was noted between precipitin and IgG (ImmunoCAP). Positive precipitin for A. fumigatus suggests more active diseases. Cross-reactivity may exist between antibodies to different Aspergillus spp. Therefore, the type III hypersensitivity results in ABPA diagnosis should be carefully evaluated.

Allergic Bronchopulmonary Mycosis due to Exposure to Eurotium herbariorum after the Great East Japan Earthquake.

BACKGROUND: Indoor mold levels typically increase after natural disasters, flooding, and water damage. Eurotium herbariorum is the sexual stage of Aspergillus glaucus. Case Presentation A 66-year-old, Japanese male, ex-smoker had been diagnosed with bronchial asthma when he was five years old; he achieved remission at the age of 13 years. He was displaced from his home during the Great East Japan Earthquake on March 11, 2011 and moved to temporary housing in Miyagi Prefecture in June 2011. He experienced the first episode of chest tightness, coughing, and wheezing in February 2012, when he again was diagnosed as having bronchial asthma. Mycofloral surveillance detected high counts of Eurotium in the air of his bedroom, kitchen, and living room, with a maximal fungal count of 163,200 colony-forming units per cubic meter (CFU/m3). Although Cladosporium and Penicillium typically predominate in the indoor air of residential dwellings, only low levels of these organisms were present in the patient's home. Morphologic identification confirmed the isolates as E. herbariorum. The patient had positive reactions to E. herbariorum in skin prick testing and the presence of antigen-specific precipitating antibodies to E. herbariorum. Computed tomography of the chest in August 2013 revealed central bronchiectasis and bronchial wall thickening. The patient experienced late reactions after provocation testing with E. herbariorum. CONCLUSION: This report presents the rare case of a patient who developed allergic bronchopulmonary mycosis (ABPM) due to exposure to E. herbariorum during temporary housing after the Great East Japan Earthquake. Oshikata C , Watanabe M , Saito A , Ishida M , Kobayashi S , Konuma R , Kamata Y , Terajima J , Cho J , Yanai M , Tsurikisawa N . Allergic bronchopulmonary mycosis due to exposure to eurotium herbariorum after the Great East Japan Earthquake. Prehosp Disaster Med. 2017;32(6):688-690.

LONGITUDINAL MONITORING OF TREE AIRBORNE POLLEN IN JAPAN.

RATIONAL: In Japan patients with Japanese Cedar (JC) pollinosis have increased nation widely since the latter of 1970's. The Ministry of Health and Welfare of Japanese Governments has begun to take preventive measures against JC pollinosis and airborne pollen monitoring has begun to investigate as a causative agent since 1986. We have estimated the longitudinal investigation result for successful prevention and treatment against pollinosis in Japan. METHOD: We have monitored airborne pollen all year around since July 1986 by gravitational pollen sampler, Durham's sampler, at more than 20 locations in the Japanese Islands. Pollen samples were sent to our hospital and counted pollen number per cm2 after stained by Calberla solution and then classified main pollen grains as a causative agent of pollinosis. RESULT AND DISCUSSION: JC pollen number was the most of all, more than 40%, next cypress family, about 20%. They were occupied of more than 60% of all and they increased with the remarkable annual fluctuation as the allergen of JC pollinosis. Beech family pollen counting were also increasing and occupied about 10% of all pollen counts. In Hokkaido the prevalence of birch family pollen count was larger than that in other districts. There is cross-reactivity between beech and birch family which related with oral allergic syndrome.Perspective and Conclusion: In future new occurrences of oral allergy syndrome due to increasing allergic tree pollen grains would be appeared. The contentious pollen research should be important for patients with pollinosis in Japan.

Weight loss in the early stage of progressive supranuclear palsy.

OBJECTIVES: To clarify whether weight change in patients with Parkinson's disease (PD) or progressive supranuclear palsy (PSP) is caused by the disease itself or secondarily by other factors. MATERIALS AND METHODS: We conducted a retrospective analysis of 51 patients with PD and 14 patients with PSP, especially during the early stage of their diseases. All patients were independent in terms of their activities of daily living and did not have any feeding difficulty. RESULTS: The body mass index measured within 3 years after the disease onset did not show a significant difference between the two diseases. However, the subsequent weight was stable in patients with PD and significantly decreased in patients with PSP. CONCLUSIONS: Weight loss begins in the early stage of PSP, whereas dopaminergic treatment may contribute to keep weight in the early stage of PD through reduction of energy expenditure and/or improvement in appetite.

Allergic bronchopulmonary mycosis caused by Penicillium luteum.

A 65-year-old Japanese male had severe bronchial asthma had increased mold-containing sputum. Serum total IgE level had increased to 798 IU/mL and antigen-specific precipitating antibodies to P. luteum and P. notatum were present but not those reactive toward any species of Aspergillus. Chest computed tomography revealed central bronchiectasis and bronchial wall thickness. After antigen-specific provocation with 10 mg/mL of P. luteum, the patient developed asthma exacerbation, but not with A. fumigatus. We present a rare case of Penicillium-induced allergic bronchopulmonary mycosis caused by P. luteum.

Effective allergen avoidance for reducing exposure to house dust mite allergens and improving disease management in adult atopic asthmatics.

OBJECTIVE: We investigated the best strategy for adult asthmatics to avoid exposure to Dermatophagoides group (Der-1) allergens. METHODS: Adult atopic asthmatics (n = 111) followed a 32-item checklist for avoiding Der-1 allergen exposure. Twenty-five patients were excluded through incomplete sampling; 50 remaining patients encased their pillows/futons/mattresses in microfine-fiber covers, 13 used vacuum cleaners with dust-mite-collection nozzles, and 23 acted as non-intervention controls. During August-October 2010 and August-October 2011, dust samples were collected in Petri dishes placed in bedrooms for 2 weeks and from mattresses/futons by using adhesive tape on one morning. A Der-1 level decrease was defined as a mean 2011 Der-1 level of <1 as a ratio of the 2010 level on tape or Petri dish samples. We analyzed the associations between Der-1 level change (by ELISA) and % weekly variability in peak expiratory flow (PEF) or fraction of exhaled nitric oxide (FeNO) after intervention. RESULTS: Der-1 levels decreased significantly in the covers group but not the vacuuming group. FeNO levels and PEF variability were unchanged in both groups. In patients whose Petri dish or tape samples showed decreased Der-1 levels, the % PEF variability was lower in 2011 than in 2010, but FeNO levels were unchanged. Three interventions (vacuuming all family members' mattress/futon surfaces at least weekly or after exposure of the futons to sunlight, and floor wiping before vacuuming), plus using covers, were the most effective management strategy in reducing Der-1 levels. CONCLUSIONS: This environmental and bedding maintenance program may help manage adult atopic asthma.

Cross-reactivity between major IgE core epitopes on Cry j 2 allergen of Japanese cedar pollen and relevant sequences on Cha o 2 allergen of Japanese cypress pollen.

BACKGROUND: Cry j 2 and Cha o 2 are major allergens in Japanese cedar (Cryptomeria japonica; CJ) and Japanese cypress (Chamaecyparis obtusa; CO) pollen, respectively. Here, we assessed the epitopes related to the cross-reactivity between Cry j 2 and Cha o 2 using in vitro analyses. METHODS: Peptides were synthesized based on Cry j 2 sequential epitopes and relevant Cha o 2 amino acid sequences. Four representative monoclonal antibodies (mAbs) against Cry j 2 were used according to their epitope recognitions. Serum samples were collected from 31 patients with CJ pollinosis. To investigate cross-reactivity between Cry j 2 and Cha o 2, ELISA and inhibition ELISA were performed with mAbs and sera from patients with CJ pollinosis. RESULTS: Two of four mAbs had reactivity to both Cry j 2 and Cha o 2. Of these two mAbs, one mAb (T27) recognized the amino acid sequence (169)KVVNGRTV(176) on Cha o 2. This is related to the core epitope (169)KWVNGREI(176) on Cry j 2, which is an important IgE epitope. In addition, we found that these correlative sequences and purified allergens showed cross-reactivity between Cry j 2 and Cha o 2 in IgE of CJ patients. CONCLUSIONS: We demonstrated the importance of (169)KVVNGRTV(176) in Cha o 2 for cross-reactivity with the Cry j 2 epitope (169)KWVNGREI(176), which plays an important role in allergenicity in CJ pollinosis. Our results are useful for the development of safer and more efficient therapeutic strategies for the treatment of CJ and CO pollen allergies.

Japanese Society of Allergology task force report on standardization of house dust mite allergen vaccines - secondary publication.

BACKGROUND: In the 1990s, the Japanese Society of Allergology (JSA) standardized Japanese cedar pollen allergen vaccines. In the present study, the task force for house dust mite (HDM) allergen standardization of the Committee for Allergens and Immunotherapy of JSA reports the standardization of HDM allergen vaccines in Japan. METHODS: In vivo allergenic potency was determined by intradermal testing of 51 Japanese adults with positive serum specific IgE to HDM allergens. In vitro total IgE binding potency was analyzed by competition ELISA using a pooled serum, with sera obtained from 10 allergic patients. The amounts of HDM group 1 (Der 1) and group 2 major allergens in eight HDM allergen extracts were measured by sandwich ELISAs. Correlation between the in vitro total IgE binding potency and major allergen levels was analyzed. RESULTS: We selected a JSA reference HDM extract and determined its in vivo allergenic potency. The in vitro total IgE binding potency significantly correlated with Der 1 content, group 2 allergen content, and their combined amount, indicating that measurement of major allergen contents can be used as a surrogate in vitro assay. CONCLUSIONS: The task force determined the in vivo allergenic potency (100,000 JAU/ml) and Der 1 content (38.5 µg/ml) of the JSA reference HDM extract, selected the measurement of Der 1 content as the surrogate in vitro assay, and decided that manufacturers can label a HDM allergen extract as having a titer of 100,000 JAU/ml if it contains 22.2-66.7 µg/ml of Der 1.

IgE Abs to Der p 1 and Der p 2 as diagnostic markers of house dust mite allergy as defined by a bronchoprovocation test.

BACKGROUND: Limited information is available regarding the clinical usefulness of measuring the levels of IgE to allergen components from house dust mites (HDMs) in the diagnosis of genuine HDM allergy. METHODS: To evaluate the diagnostic usefulness of measuring levels of serum IgE antibodies (Abs) to allergen components from Dermatophagoides pteronyssinus (DP) as a predictor of immediate asthmatic response (IAR) to bronchoprovocation, we studied 55 DP-sensitized asthmatic patients who underwent a bronchoprovocation test using crude DP extract. The levels of IgE Abs to crude DP, nDer p 1, rDer p 2, and rDer p 10 in patients who showed IAR (n = 41) were compared with those in patients who showed no IAR (n = 14). RESULTS: While the frequencies of positivity for IgE Abs to nDer p 1 and rDer p 2 among the entire study population were 89 and 86%, respectively, all patients with IAR tested positive for both of them with high IgE concentrations. The areas under the receiver operating characteristic curves for IgE to nDer p 1 and rDer p 2 as predictors of IAR were 0.913 and 0.906, respectively. The specificity of IgE to nDer p 1 and rDer p 2 was higher than IgE to crude DP even at low cut-off points. CONCLUSIONS: IgE to nDer p 1 and/or rDer p 2 was highly predictive of allergen-induced IAR. These findings validate the clinical usefulness of measuring the levels of IgE to nDer p 1 and rDer p 2 as a diagnostic tool for genuine HDM allergy.

[TRANSITION OF AIRBORNE FUNGI DURING 20-YEARS FROM 1993 TO 2013 IN SAGAMIHARA].

BACKGROUND: Airborne fungi have been surveyed every week during the 20 years from 1993 to 2013 in Sagamihara. This is a follow up of 1983 to 1992 survey at the same sampling station, using the same methods. OBJECTIVE: We analyzed the transition of airborne fungi of 20-years. METHODS: Using a settle plate method, air sampling was performed by exposing 90 mm settle plates containing potato dextrose agar to the air for 10 min. The plates were incubated at 25℃ for 7-14 days. The fungi were identified and counted. RESULTS: The average of number total fungi colonies during 20 years were 507 colony forming units (CFU)/5 plate every year. The most common fungi found, except for yeasts and sterile mycelium, were Cladosporium, Alternaria, Penicillium, Ulocadium, Fusarium, Arthrinium, Epicoccum, Aureobasidium, Curvularia, Nigrospora and Aspergillus. A significant correlation was observed between the number total fungi clonies and number of Cladosporium colonies. Although Alternaria, Arthrinium, Epicoccum and Curvularia were significantly reduced as compared 10 years from 1983 to 1992, Cladosporium and Penicillium were comparable. CONCLUSION: Cladosporium was most predominant fungi during the 20 years. This study is very valuable in that the transition of airborne fungi revealed by long-term measurement.

Occupational asthma from exposure to rye flour in a Japanese baker.

Three years after beginning employment at a bakery, a 32-year-old Japanese man began experiencing acute asthma exacerbations after exposure to rye flour. Antigen-specific serum IgE antibodies were detected to the albumin and globulin, gliadin, prolamin, and glutenin protein fractions of rye flour purified from the crude antigen, but only to the albumin and globulin fraction of wheat flour. The histamine concentration producing one-half maximal effect was lower for all four rye flour fractions than for the wheat flour fractions. After inhalation of the albumin and globulin fraction of rye flour, forced expiratory volume in 1 sec decreased to 77.7% of that pre-provocation. To our knowledge, this is the first report of baker's asthma due to rye flour in Japan.

[Japanese Society of Allergology Task Force Report on standardization of house dust mite allergen vaccines].

BACKGROUND: In the 1990s, the Japanese Society of Allergology (JSA) standardized Japanese cedar pollen allergen vaccines. In the present study, the task force for house dust mite (HDM) allergen standardization of the Committee for Allergens and Immunotherapy of JSA reports the standardization of HDM allergen vaccines in Japan. METHODS: In vivo allergenic potency was determined by intradermal testing of 51 Japanese adults with positive serum specific IgE to HDM allergens. In vitro total IgE binding potency was analyzed by the competitive ELISA using a pooled serum, with sera obtained from 10 allergic patients. Concentrations of HDM group 1 (Der 1) and group 2 major allergens in eight HDM allergen extracts were measured by sandwich ELISAs. Correlation between the in vitro total IgE binding potency and major allergen levels was analyzed. RESULTS: We selected a JSA reference HDM extract and determined its in vivo allergenic potency. The in vitro total IgE binding potency significantly correlated with Der 1 content, group 2 allergen content, and their combined amount, indicating that measurement of major allergen contents can be used as a surrogate in vitro assay. CONCLUSIONS: The task force determined the in vivo allergenic potency (100000 JAU/ml) and Der 1 content (38.5 µg/ml) of the JSA reference HDM extract, selected the measurement of Der 1 content as the surrogate in vitro assay, and decided that manufacturers can label a HDM allergen extract as having a titer of 100000 JAU/ml if it contains 22.2-66.7 µg/ml of Der 1.