Complementary and alternative medicine for allergic rhinitis in Japan.

BACKGROUND: Complementary and alternative medicine (CAM) is extensively used in patients with allergic diseases worldwide. The purpose of this study was to investigate the actual situation of CAM practice in the treatment of allergic rhinitis. METHODS: We distributed questionnaires to otolaryngologists at 114 facilities in Japan. The subjects who participated in this study included children <16 years of age and adults ≥16 years of age diagnosed with allergic rhinitis by otolaryngologists. The survey was performed in the period from September 2007 to August 2009. Furthermore, we performed the same investigation out of the hospital setting, such as during general health examinations. All questionnaires were returned to Chiba University and analyzed. RESULTS: The proportions of patients who had ever experimented with CAM in the hospital survey were 7.1% (225/3170) and 19.2% (1416/7363) of children and adults, respectively. Approximately 36.2% of the adult patients thought that the treatments were effective. The main reasons for CAM use were safety, convenience and low price. However, the group who spent more than $1000 on CAM felt more dissatisfaction and anxiety related to treatment at the hospital. The situation of CAM practice was not consistent and was instead influenced by the backgrounds of the subjects. CONCLUSIONS: Many patients who receive CAM report feeling that the effects of treatment provided by hospitals are insufficient and have concerns about the side effects of such treatments. Information regarding standard treatments, as described in the guidelines, should become widely known and diffused, and strong communication with patients should be considered.

Guiding principles of sublingual immunotherapy for allergic rhinitis in Japanese patients.

OBJECTIVE: Sublingual immunotherapy (SLIT) appears to offer practical advantages for the treatment of allergic rhinitis (AR). Based on a review of the scientific literature, we present recommendations as guiding principles to administer SLIT safely. METHODS: Clinical questions concerning SLIT were prepared. Literature published between January 2003 and December 2012 was searched from PubMed, the Cochrane Library, and Japana Centra Revuo Medicina. Qualified studies were analyzed and the results were evaluated, consolidated, and codified. We answered 17 clinical questions and, based on this, presented evidence-based recommendations. RESULTS: Sublingual immunotherapy improved symptoms (e.g., quality of life [QOL]) and reduced medication scores in seasonal AR and perennial AR. Most SLIT-induced adverse effects were local oral reactions, although systemic adverse effects such as gastrointestinal symptoms, urticaria, and asthma are occasionally reported. There have been no reports of lethal anaphylactic reactions by SLIT. When SLIT is continued for 3-4 years, its effect persists long after discontinuation. CONCLUSION: A correct diagnosis of AR and sufficient informed consent from patients are required before initiating SLIT. Sublingual immunotherapy should be continued for 3 years or longer. The initial administration of SLIT during the uptitration of an allergen vaccine and the general condition of patients are critical for the safe performance of SLIT.

Characteristics of the Chiba environmental challenge chamber.

BACKGROUND: An environmental challenge chamber (ECC), which we refer to as the α-chamber, was built at Chiba University in 2008. The aim of this study was to validate the functionality of the ECC. METHODS: The stability of the pollen distribution and concentration in the ECC and symptoms of patients with Japanese cedar pollinosis induced by cedar pollen exposure were examined. Carryover effects of symptoms induced by different exposure protocols and correlations between symptoms induced in the ECC and those in the natural cedar pollen season were also determined. All the studies using the α-chamber were conducted out of the cedar pollen season. RESULTS: The severity of symptoms in the chamber reached a peak about 2 hours after the start of pollen exposure and plateaued thereafter. After subjects left the chamber, the symptoms persisted for several days. There was no significant difference between the severity of symptoms at exposure levels of 8000 and 12000 grains/m3. The symptoms were significantly increased by exposure for 3 consecutive days; however, there were no carryover effects in a study performed with a two-week interval. The total nasal symptom score (TNSS) in the natural pollen season showed a weak correlation with the mean TNSS on the day of exposure and the following 3 days. Symptoms in the ECC also had weak correlations with those in the early natural pollen season. CONCLUSIONS: The ECC under well-controlled conditions is suitable for clinical studies and might accelerate development of treatment for seasonal allergic rhinitis. A complete evaluation requires inclusion of the persistent reaction after subjects leave the ECC.

Guiding principles of subcutaneous immunotherapy for allergic rhinitis in Japan.

OBJECTIVE: In anticipation of the development of guidelines for antigen-specific subcutaneous immunotherapy (SCIT), we present recommendations that can serve as guiding principles based on a review of the scientific literature. METHODS: Clinical questions (CQs) concerning SCIT were prepared. Literature searches for publications between January 1990 and February 2011 were performed in PubMed, the Cochrane Library, and Japana Centra Revuo Medicina Web version 4. Qualified studies were analyzed and the results were evaluated, consolidated, and codified. RESULTS: We present answers for 13 CQs on the indications, methods, effectiveness and mechanisms of SCIT, with evidence-based recommendations. CONCLUSION: The guiding principles are intended to be applied to children (≤15 years old) and adults (≥16 years old) with allergic rhinitis (AR). These principles can be used by otorhinolaryngologists for diagnosis of AR, evaluation of severity and rhinoscopic findings, performance of antigen challenge tests, and management of systemic anaphylactic reactions associated with SCIT.

Comparison of nasal steroid with antihistamine in prophylactic treatment against pollinosis using an environmental challenge chamber.

Environmental challenge chambers (ECC) have been used to expose people to pollen allergens within a stable atmosphere and to examine the efficacy of treatment. Although pollinosis is one of the typical IgE-mediated type I allergic diseases, allergic inflammation is thought to contribute to the fundamental pathogenesis and prophylactic treatment may reduce exacerbations of pollinosis. The purpose of this study was to compare the efficacy of prophylactic treatment with nasal steroid (mometasone furoate nasal spray) or an antihistamine (fexofenadine) in the control of cedar pollinosis using the ECC. In a randomized, double-blind two-way crossover study, 48 patients received nasal steroid or antihistamine for 7 consecutive days (days 1-7). On day 8, patients were exposed to cedar pollen (8000 grains/m(3)) in the ECC for 3 hours. Nasal symptoms induced by pollen exposure were assessed. Total nasal symptom scores (TNSSs) during the exposure in the ECC were not significantly different between the antihistamine and the nasal steroid groups. Nasal symptoms induced by pollen exposure using the ECC persisted for up to 3 days. TNSSs after pollen exposure on days 8-11 were significantly lower in the nasal steroid group compared with the antihistamine group. Prophylactic treatment with nasal steroid is more effective than antihistamine against pollinosis, particularly in the late phase. Clinical trial registration JAPIC CTI 101182 (www.clinicaltrials.jp/user/ctiMain_e.jsp).

The onset of allergic rhinitis in Japanese atopic children: a preliminary prospective study.

CONCLUSION: This preliminary prospective study suggests that background factors may differ among allergic diseases. The beneficial interventions for reducing development of allergic rhinitis (AR) are also effective for the prevention of subsequent onset of bronchial asthma (BA). OBJECTIVE: To determine the risk factors associated with onset of AR in atopic children in a prospective study. METHODS: All patients with atopic dermatitis (AD) or food allergy with or without BA who visited the Pediatric Unit of Chiba University Hospital from 2005 to 2006 were enrolled in the study and received allergy examinations every 3-6 months. RESULTS: A total of 100 patients were followed up for more than 2 years. Among the 60 patients without BA at entry to the study, 12 developed BA during the follow-up period. Development of AR preceded BA in 10 of the 12 patients (83.3%). In the background factors at the entry, positive sensitization to house dust mite (HDM) was significantly related to development of BA. Among the 48 patients without AR, 20 developed AR. High titers of serum HDM-specific IgE and high eosinophil counts in blood, and detection of eosinophils in nasal smears at the entry were significantly related to development of AR.

Immunological parameters associated with the development of allergic rhinitis: a preliminary prospective study.

BACKGROUND: Many subjects are sensitized to Japanese cedar pollen but do not develop allergic rhinitis (AR). The aim of this study was to examine the immunologic parameters related to the development of AR in sensitized subjects. METHODS: The subjects were 33 adults who were sensitized to Japanese cedar pollen, but had not developed as of 2007. Cedar pollen-specific IgE (sIgE) and total IgE (tIgE) in serum, cedar pollen antigen (Cry j 1) Cry j-specific memory Th2 cell clone size, and the Cry j-specific induced regulatory T cell (iTreg) level were examined before and after the season in 2008. RESULTS: Eight of the 33 subjects developed cedar pollinosis. The sIgE titers before the season in these eight subjects did not differ from those in the subjects who did not develop pollinosis, but the titers after the season were significantly higher in the group that developed pollinosis. The sIgE/tIgE ratio increased in almost all subjects, but the ratio was significantly higher before the season in the subjects who developed pollinosis. Cry j-specific Th2 cells were detected in all subjects, but the clone size only increased in those that developed pollinosis. The Cry j-specific iTreg population did not differ between the two groups. CONCLUSION: A high sIgE/tIgE ratio before the season may be predictive of development of pollinosis, and an increase in the allergen-specific Th2 clone size during the pollen season could be a biomarker for pollinosis. The role of allergen-specific iTreg cells in the development of pollinosis could not be clarified in this preliminary study.

Sublingual administration of Lactobacillus paracasei KW3110 inhibits Th2-dependent allergic responses via upregulation of PD-L2 on dendritic cells.

Lactic acid bacteria have potential in immunomodulation therapy, but their clinical efficacy and underlying mechanisms are unclear. We aimed to clarify the anti-allergic immune responses induced by intragastric and sublingual administration of heat-killed Lactobacillus paracasei KW3110 and Lactobacillus acidophilus L-92. The KW3110 strain (but not the L-92 strain) enhanced ovalbumin (OVA)-induced expression of CCR-7 and PD-L2 in murine dendritic cells (DCs), and strongly inhibited IL-5 and IL-13 production in vitro in co-cultures with Th2-skewed CD4(+) T cells from DO11.10 transgenic mice. Sublingual administration of low-dose KW3110 (but not L-92) to OVA-sensitized mice selectively suppressed serum IgE production and Th2 cytokine expression in cervical lymph nodes, and significantly improved symptoms after OVA provocation in vivo. KW3110 probably accelerates DC migration into the regional lymph nodes and inhibits Th2 cytokine production through enhanced CCR-7 and PD-L2 expression. Thus, sublingual KW3110 administration may be effective in reducing allergic inflammation.

Association of the MMP9 gene with childhood cedar pollen sensitization and pollinosis.

Matrix metalloproteinase 9 (MMP9) gene has been shown to be involved in the pathogenesis of allergic rhinitis (AR) and asthma. Previous studies suggested that single-nucleotide polymorphisms (SNPs) of the MMP9 gene conferred a risk for childhood asthma. However, whether the SNPs confer a risk for AR has not been previously investigated. The objective of this study was to investigate whether SNPs of the MMP9 gene are associated with risk of seasonal AR (pollinosis), perennial AR and allergen sensitization. A total of 670 school children were recruited in Japan and genotyped for functional polymorphism in the promoter (-1590C/T: rs3918242) and three amino-acid substitutions (R297Q: rs17576; P574R: rs2250889; R668Q: rs17577). Serum levels of total and specific IgE were determined. Disease status and other clinical characteristics of the subjects were investigated using a questionnaire. Associations between the MMP9 SNPs and both AR and serum IgE levels were evaluated. -1590C/T showed significant association with cedar pollinosis (corrected P (Pcor)=0.039). R668Q was in strong linkage disequilibrium (LD) with -1590C/T and showed significant association with cedar pollinosis (Pcor=0.023) and serum cedar pollen-specific IgE level (Pcor=0.022). A haplotype associated with -1590T and 668Q showed a significant association with cedar pollinosis, orchard grass pollinosis and cedar pollen-specific IgE (Pcor=0.0012, Pcor=0.0059 and Pcor=0.0041, respectively). R297Q and P574R were in weak LD with the rest of the SNPs and did not show significant association with disease. Compared with wild-type MMP9 protein (279R-574P-668R), a variant enzyme (279R-574P-668Q) that showed association with pollinosis had lower activity. However, lower enzyme activity was not associated with disease risk because another variant (279Q-574R-668R) showed lower enzyme activity but was not associated with pollinosis. The -1590T allele and its corresponding haplotype was associated with higher promoter activity and with pollen-specific IgE levels and pollinosis, suggesting that -1590C/T may have more impact on sensitization and disease development than R668Q. Our results suggest that the MMP9 gene confers susceptibility to cedar pollinosis in Japanese children. The MMP9 gene may be associated with pollinosis through sensitization processes.

Effects of aging on the natural history of seasonal allergic rhinitis in middle-aged subjects in South chiba, Japan.

BACKGROUND: The natural history of allergic rhinitis has been examined in a few longitudinal studies. The purpose of the study was to investigate the course, development and remission of seasonal allergic rhinitis (SAR) over 10 successive years in middle-aged subjects. METHODS: An annual questionnaire survey on allergic rhinitis symptoms combined with an examination of specific IgE has been undertaken in a rural town in south Chiba since 1995. The analyzed subjects were 703 residents who underwent every examination in 1995, 2004 and 2005. In the last 15 years, the annual pollen count in Chiba was highest in 2005. RESULTS: The sensitization rates to cedar pollen decreased with age in the same subject groups over 10 years, but the prevalence of SAR was higher in 2005 compared with 1995. Of the 52 subjects with SAR in 1995, the symptoms had disappeared in 10 subjects in 2005. Specific IgE had converted to negative or borderline in 4 of these patients, had decreased but was still positive in 4 and was increased or unchanged in 2. During the 10-year period, 22 subjects developed SAR, of whom 12 had increased specific IgE and 10 had similar or decreased specific IgE in 2005. CONCLUSION: SAR induced by cedar pollen takes a chronic course in the majority of middle-aged patients in south Chiba, Japan. The prevalence of SAR increased over 10 years due to a high level of pollen exposure. Changes in specific IgE were not directly associated with the development or remission of SAR.

Nasal submucosal administration of antigen-presenting cells induces effective immunological responses in cancer immunotherapy.

Human NKT cells are known to have strong antitumor activities and to be activated by specific ligand, α-galactosylceramide (αGelCer). We examined the migration pattern of αGalCer-pulsed DCs and the immune responses after administration by different routes. DCs injected into nasal submucosa quickly migrated to the lateral neck lymph rather than the lateral lymph nodes. The absolute number of NKT cells and the IFN-γ-producing cells increased in peripheral blood after injection of the DCs into nasal submucosa. We conducted a phase I study with αGalCer-pulsed DCs administered in nasal submucosa of patients with head and neck cancer, and evaluated safety and feasibility. The results showed that nasal submucosal administration of α-GalCer-pulsed DCs was safe and a smaller number of these DCs could exhibit significant immune responses and some positive clinical effects. In additional study, the use of the intra-arterial infusion of activated NKT cells and the submucosal injection of α-GalCer-pulsed DCs has been shown to induce significant antitumor immunity and had beneficial clinical effects in the management of advanced head and neck squamous cell carcinoma. The NKT cell-based cancer immunotherapy may be helpful in management of head and neck cancer and needs to be explored in further detail.

The influence of environmental exposure to formaldehyde in nasal mucosa of medical students during cadaver dissection.

BACKGROUND: Environmental exposure to formaldehyde is commonly associated with clinical symptoms such as mucosal irritation and olfactory disorders. However, the impact of such exposure on the development of mucosal inflammation and its outcome has not been carefully evaluated. METHODS: The observational non-comparative study was planned. The study population consisted of group of 41 medical students who had signed up for a cadaver dissection course as part of their gross anatomy teaching at the school of medicine Chiba University in Japan. During such dissection course, the students are exposed to variable levels of environmental formaldehyde routinely employed for the preservation the cadavers. The subjects were evaluated by a detailed medical examination. We measured their serum IgE levels. In addition, an olfaction test and nasal mucosal sensitivity to histamine was serially determined, immediately before and after the course and 6 months after the completion of the course. RESULTS: Olfactory abnormalities were observed in 13/41 (32%) subjects and increased nasal mucosal hypersensitivity to histamine was observed in 17/41 (41%) during and immediately after completion of the course. These subjects had evidence of preexisting allergic rhinitis. 6/41 (15%) other students with no prior evidence of allergic rhinitis also exhibited formaldehyde associated clinical symptoms during the dissecting course. However, the symptoms disappeared upon completion of the course in all subjects studied. CONCLUSIONS: Temporary abnormalities in the olfaction test and increased nasal mucosal hypersensitivity to histamine were observed in a few students with preexisting allergic rhinitis after environmental exposure of high concentrations of formaldehyde. These effects appeared to be transient.

Increase of regulatory T cells and the ratio of specific IgE to total IgE are candidates for response monitoring or prognostic biomarkers in 2-year sublingual immunotherapy (SLIT) for Japanese cedar pollinosis.

The aims of this study were to examine the therapeutic effects of sublingual immunotherapy (SLIT) and to identify potential biomarkers that would predict the therapeutic response in a randomized, double-blind, placebo-controlled clinical trial. The trial was carried out over two pollinosis seasons in 2007 and 2008. Carry-over therapeutic effects were analyzed in 2009. SLIT significantly ameliorated the symptoms of pollinosis during the 2008 and 2009 pollen seasons. Cry j 1-specific cytokine production in a subgroup of patients with mild disease in the SLIT group was significantly attenuated. The ratio of specific IgE to total IgE before treatment correlated with the symptom-medication score in the SLIT group in 2008. Patients with increased Cry j 1-iTreg in the SLIT group had significantly improved QOL and QOL-symptom scores. In summary, the specific IgE to total IgE ratio and upregulation of Cry j 1-iTreg are candidates for biomarker of the clinical response to SLIT.

A randomized, double-blind, placebo-controlled study of ten-cha (Rubus suavissimus) on house dust mite allergic rhinitis.

OBJECTIVE: Self-care with ten-cha is the most common complementary alternative medicine for allergic rhinitis in Japan, but evidence for an actual therapeutic effect is lacking. The purpose of the study was to investigate the effect of ten-cha (Rubus suavissimus) on house dust mite allergic rhinitis. METHODS: The study was performed in the otolaryngology departments of 5 facilities (Chiba University, Kagoshima University, Fukui University, Okayama University, and Nippon Medical School) from July to December 2009. A randomized double-blind study was performed with central enrollment and allocation. The subjects ingested 400mg of ten-cha extract or placebo (3 capsules/day) daily for 4 weeks as a food intervention. The number of subjects was chosen with anticipation of an effect equivalent to that of mast cell-stabilizing drugs. A nasal allergy diary-based symptom score and a QOL score were used for evaluation. RESULTS: The ten-cha and placebo groups included 47 and 42 subjects, respectively. The improvement rates for sneeze, nasal discharge, nasal obstruction, and symptom scores were greater in the ten-cha group than in the placebo group throughout the intervention period, and the effect tended to increase with time in the ten-cha group. However, the differences between the groups were not significant. QOL was not significantly improved in either group. CONCLUSION: Ingestion of ten-cha had an effect on allergic rhinitis, but the effect of Ten-Cha was limited and did not differ significantly from placebo. These results suggest that ten-cha does not exhibit an effect equivalent to mast cell-stabilizing drugs at the dose used in this study.

Migration and immunological reaction after the administration of αGalCer-pulsed antigen-presenting cells into the submucosa of patients with head and neck cancer.

BACKGROUND: Antigen-presenting cells (APCs) play a crucial role in the induction of immune responses. However, the optimal administration route of tumor-specific APCs for inducing effective immunological responses via cancer immunotherapy remains to be elucidated. Human NKT cells are known to have strong anti-tumor activities and are activated by the specific ligand, namely, α-galactosylceramide (αGalCer). METHODS: Seventeen patients with head and neck squamous cell carcinoma (HNSCC) were enrolled in this study. Patients received an injection of αGalCer-pulsed APCs into the nasal, or the oral floor submucosa. Then total body image and single photon emission computed tomography (SPECT) images were examined. The immunological responses including the number of peripheral blood NKT cells, anti-tumor activities and the CD4(+) CD25(high) Foxp3(+) T cells (Tregs) induced following APCs were also compared. RESULTS: APCs injected into the nasal submucosa quickly migrated to the lateral lymph nodes and those injected into the oral floor submucosa dominantly migrated to the submandibular nodes rather than the lateral lymph nodes. An increase in the absolute number of NKT cells and the IFN-γ producing cells was observed in peripheral blood after injection of the APCs into the nasal submucosa, however, these anti-tumor activities were not detected and the increased frequency of Treg cells were observed after administration into oral floor. CONCLUSIONS: These results indicate that a different administration route of APCs has the potential to bring a different immunological reaction. The submucosal administration of αGalCer into the oral submucosa tends to induce immunological suppression.

Induction of NKT cell-specific immune responses in cancer tissues after NKT cell-targeted adoptive immunotherapy.

Vα24 natural killer T (NKT) cells have potent anti-tumor activity. We performed a phase II clinical study in patients with head and neck squamous cell carcinoma (HNSCC) using ex vivo expanded Vα24 NKT cells and α-galactosylceramide (αGalCer; KRN7000)-pulsed antigen-presenting cells (APCs) to investigate the efficacy and induction of NKT cell-specific immune responses. The subjects were 10 patients with locally recurrent and operable HNSCC. One course of nasal submucosal administration of αGalCer-pulsed APCs and intra-arterial infusion of activated NKT cells via tumor-feeding arteries was given before salvage surgery. Anti-tumor effects, NKT cell-specific immune responses in extirpated cancer tissue and peripheral blood, safety, and pathological effects were evaluated. Five cases achieved objective tumor regression. The number of NKT cells increased in cancer tissues in 7 cases and was associated with tumor regression. The combination therapy induced NKT cell-specific immune responses in cancer tissues that were associated with beneficial clinical effects.

Glutathione S-transferase P1 (GSTP1) suppresses cell apoptosis and its regulation by miR-133α in head and neck squamous cell carcinoma (HNSCC).

The glutathione S-transferase P1 (GSTP1) protein plays several critical roles in both normal and neoplastic cells, including phase II xenobiotic metabolism, stress responses, signaling and apoptosis. Overexpression of GSTP1 has been observed in many types of cancer, including head and neck squamous cell carcinoma (HNSCC). However, the role of GSTP1 in HNSCC is not well understood. We investigated the role of GSTP1 in two HNSCC cell lines, HSC3 and SAS. Silencing of GSTP1 revealed that cancer cell proliferation was significantly decreased in both cell lines. In addition, the frequency of apoptotic cells increased following si-GSTP1 transfection of HSC3 and SAS cell lines. Growing evidence suggests that microRNAs (miRNAs) negatively regulate gene expression and can function as oncogenes or tumor suppressors in human cancer. Based on the results of web-based searches, miR-133α is a candidate miRNA targeting GSTP1. Down-regulation of miR-133α has been reported in many types of human cancer, including HNSCC. Transient transfection of miR-133α repressed the expression of GSTP1 at both the mRNA and protein levels. The signal from a luciferase reporter was significantly decreased at one miR-133α target site at the 3'UTR of GSTP1, suggesting that miR-133α directly regulates GSTP1. Our data indicate that GSTP1 may have an oncogenic function and may be regulated by miR-133α, a tumor suppressive miRNA in HNSCC. The identification of a novel oncogenic pathway could provide new insights into potential mechanisms of HNSCC carcinogenesis.

Reevaluation of pollen quantitation by an automatic pollen counter.

Accurate and detailed pollen monitoring is useful for selection of medication and for allergen avoidance in patients with allergic rhinitis. Burkard and Durham pollen samplers are commonly used, but are labor and time intensive. In contrast, automatic pollen counters allow simple real-time pollen counting; however, these instruments have difficulty in distinguishing pollen from small nonpollen airborne particles. Misidentification and underestimation rates for an automatic pollen counter were examined to improve the accuracy of the pollen count. The characteristics of the automatic pollen counter were determined in a chamber study with exposure to cedar pollens or soil grains. The cedar pollen counts were monitored in 2006 and 2007, and compared with those from a Durham sampler. The pollen counts from the automatic counter showed a good correlation (r > 0.7) with those from the Durham sampler when pollen dispersal was high, but a poor correlation (r < 0.5) when pollen dispersal was low. The new correction method, which took into account the misidentification and underestimation, improved this correlation to r > 0.7 during the pollen season. The accuracy of automatic pollen counting can be improved using a correction to include rates of underestimation and misidentification in a particular geographical area.

Sublingual immunotherapy with house dust extract for house dust-mite allergic rhinitis in children.

BACKGROUND: House dust extract is used in conventional immunotherapy for house dust-mite (HDM) allergic rhinitis in Japan. However, an alternative administration route is desired. The aims of the present double blind, placebo-controlled trial were to evaluate the therapeutic efficacy and safety of sublingual immunotherapy (SLIT) with house dust extract in pediatric patients with HDM allergic rhinitis. METHODS: The study population comprised 31 subjects (21 males and 10 females) aged from 7 to 15 years old. Twenty patients (the active group) received house dust extract and 11 received placebo via sublingual administration. Extract or placebo (1 ml) was administered at 10-fold dilution once weekly for 40 weeks. During the study period, the subjects recorded their daily nasal symptoms and use (dose and frequency) of other medications in a nasal allergy diary. RESULTS: The symptom scores in the active group began to decrease about 24 weeks after initiation of treatment and significant differences between the active and placebo groups were observed after 30 weeks. The average scores for the last four weeks of the study were significantly lower than those for the first four weeks in the active group but not in the placebo group. The only local adverse effect was a bitter taste reported by one patient. There were no other local or systemic adverse effects associated with SLIT. CONCLUSIONS: Our results suggest that SLIT with house dust extract for more than 30 weeks is safe and effective treatment for HDM allergic rhinitis in children.