Grass pollen allergoids conjugated with mannan for subcutaneous and sublingual immunotherapy: a dose-finding study.

Background: Polymerized allergoids conjugated with mannan represent a novel approach of allergen immunotherapy targeting dendritic cells. In this study, we aimed to determine the optimal dose of mannan-allergoid conjugates derived from grass pollen (Phleum pratense and Dactylis glomerata) administered via either the subcutaneous or sublingual route. Methods: A randomized, double-blind, placebo-controlled trial with a double-dummy design was conducted, involving 162 participants across 12 centers in Spain. Subjects were randomly allocated to one of nine different treatment groups, each receiving either placebo or active treatment at doses of 500, 1,000, 3,000, or 5,000 mTU/mL over four months. Each participant received five subcutaneous (SC) doses of 0.5 mL each, every 30 days, and a daily sublingual (SL) dose of 0.2 mL. Participants who received active treatment through SC, received placebo through SL. Participants who received active treatment through SL, received placebo SC. One Group, as control, received bot SC and SL placebo. The primary efficacy outcome was the improvement in titrated nasal provocation tests (NPT) at the end of the study compared to baseline. Secondary outcomes included specific antibody (IgG4, IgE) and cellular (IL-10 producing and regulatory T cell) responses. All adverse events and side reactions were recorded and assessed. Results: Post-treatment, the active groups showed improvements in NPT ranging from 33% to 53%, with the highest doses showing the greatest improvements regardless of the administration route. In comparison, the placebo group showed a 12% improvement. Significant differences over placebo were observed at doses of 3,000 mTU/mL (p=0.049 for SL, p=0.015 for SC) and 5,000 mTU/mL (p=0.011 for SL, p=0.015 for SC). A dose-dependent increase in IgG4 was observed following SC administration, and an increase in IL-10 producing cells for both routes of administration. No serious systemic or local adverse reactions were recorded, and no adrenaline was required. Conclusion: Grass pollen immunotherapy with mannan-allergoid conjugates was found to be safe and efficacious in achieving the primary outcome, whether administered via the subcutaneous or sublingual routes, at doses of 3,000 and 5,000 mTU/mL. Clinical trial registration: https://www.clinicaltrialsregister.eu/ctr-search (EudraCT), identifier 2014-005471-88; https://www.clinicaltrials.gov, identifier NCT02654223.

Reducing Recurrent Urinary Tract Infections in Women with MV140 Impacts Personal Burden of Disease: Secondary Analyses of a Randomized Placebo-controlled Efficacy Study.

Background: Recurrent urinary tract infection (rUTI) remains a major health burden for women. A randomized, double-blind, placebo-controlled trial (RCT; NCT02543827) reported that female patients with rUTI receiving a sublingual vaccine, MV140, had a reduction in rUTI and increase in UTI-free rate compared with placebo. Objective: To determine the impact of MV140 on the personal burden of disease in women with rUTI using secondary endpoint data from the pivotal RCT evaluating MV140. Design setting and participants: In the primary RCT, female patients with rUTI enrolled in Spain and UK (from October 2015 to April 2019) were randomized to placebo (6 mo) or MV140 (3 or 6 mo), and followed for 12 mo. Individuals analyzed in this secondary analysis included those in the placebo and 3-mo (recommended dose) groups. Intervention: A polybacterial sublingual vaccine, MV140 (four inactivated whole-cell bacteria-Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, and Enterococcus faecalis), or placebo. Outcome measurements and statistical analysis: Symptom severity scoring, antibiotic use, safety, and multiple aspects of quality of life (QoL; Short-Form Questionnaire [SF-36]) were assessed. Results and limitations: Compared with the placebo group (n = 76), the 3-mo vaccinated group (n = 74) experienced fewer overall UTI symptoms (mean symptom score 102.2 ± 222.9 vs 194.2 ± 178.8; p = 0.0002), fewer days on antibiotics (12.4 ± 17.7 vs 28.7 ± 25.2; p = 0.0001), and improved total, general, and physical SF-36 QoL improvement (differences in means for total SF-36 score 15.7; 95% confidence interval [CI] 8.80, 22.64; p < 0.0001), with only social function QoL showing no impact (4.07; 95% CI -4.93, 13.08; p = 0.3744). Conclusions: Three months of MV140 is associated with a reduction of the personal burden of UTI by reducing overall UTI symptoms and antibiotic use, improving QoL in women with rUTI. Patient summary: Three months of MV140 vaccine, which has previously been shown to reduce the risk of urinary tract infection safely, is associated with a reduction in the personal burden of disease.

MV130 in the Prevention of Recurrent Respiratory Tract Infections: A Retrospective Real-World Study in Children and Adults.

Respiratory tract infections (RTIs) are among the most common and important problems in clinical medicine, making antibiotics the gold standard therapeutic option regardless of their frequent viral etiology. Their excessive and inappropriate use contributes to the rapid rise of antibiotic resistance and underscores the need for alternative strategies, especially when dealing with recurrent RTIs. Prevention is the ideal alternative, but specific vaccines targeting a wide range of respiratory pathogens are scarce. MV130 is a sublingual bacterial vaccine that induces trained immunity and provides non-specific protection against respiratory pathogens in various clinical settings according to the concept of TIbV (Trained Immunity-based Vaccine). A retrospective real-world study (RWS) was conducted to evaluate the annual incidence of RTIs and the consumption of antibiotics before and after the administration of MV130, using data sourced from the medical records of 599 patients (186 children and 413 adults) who suffered from recurrent RTIs. The median number of infectious episodes in children was significantly reduced by more than 70% from 5 episodes (interquartile range (IQR) 4.0-6.0) to 1 (IQR, 0.0-2.0) (p < 0.001) after MV130. Similarly, in adults, the median number of episodes before MV130 immunization was 5 (IQR, 4.0-6.0), which dropped by more than 80% to 1 (IQR, 0.0-1.0) during the year following MV130 immunization (p < 0.001). The median number of antibiotic courses also significantly decreased for both children and adults by over 80% (p < 0.001). This RWS showed that MV130 is an effective strategy for the prevention of respiratory infections and the reduction of associated antibiotic consumption.

A randomized, double-blind, placebo-controlled trial with mannan-conjugated birch pollen allergoids.

BACKGROUND: There is still great need to develop new strategies to improve the efficacy of allergen immunotherapies with optimal safety standards for patients. A new promising approach is to couple allergoids to mannan. The objective of this phase IIa/IIb study was to identify the optimal dose of mannan-conjugated birch pollen allergoids for the short-course treatment of birch pollen-induced allergic rhinoconjunctivitis. METHODS: For this prospective, randomized, double-blind, placebo-controlled, dose-finding study, 246 birch pollen-allergic adults received 0.5 mL placebo or 1000, 3000 or 10,000 mTU/mL of mannan-conjugated birch pollen allergoids at five pre-seasonal visits. Efficacy was assessed by comparing allergic rhinoconjunctivitis symptoms and use of anti-allergic medication during the peak of the birch pollen season 2020. Immunologic, tolerability and safety effects were also analysed. RESULTS: The highest dose of mannan-conjugated birch pollen allergoids reduced the combined symptom and medication score during the peak birch pollen season by a median of 24.7% compared to placebo. The production of Bet v 1 specific IgG4 significantly increased in a dose-dependent manner (3.6- and 4.5-fold) in the 3000 and 10,000 mTU/mL groups. The Bet v 1 specific IgE/IgG4 ratio was also strongly reduced (up to -70%). No fatalities nor serious adverse events were reported, and no adrenaline was used. In total, four systemic reactions occurred (two grade I and two grade II). CONCLUSION: All doses of mannan-conjugated birch pollen allergoids can be considered as safe. Since the application of 10,000 mTU/mL resulted in the highest efficacy, this dose qualifies for further investigation.

First-in-human phase 2 trial with mite allergoids coupled to mannan in subcutaneous and sublingual immunotherapy.

BACKGROUND: Polymerized allergens conjugated to non-oxidized mannan (PM-allergoids) are novel vaccines targeting dendritic cells (DCs). Previous experimental data indicate that PM-allergoids are readily taken up by DCs and induce Treg cells. This first-in-human study was aimed to evaluate safety and to find the optimal dose of house dust mite PM-allergoid (PM-HDM) administered subcutaneously (SC) or sublingually (SL). METHODS: In a randomized, double-blind, double-dummy, placebo-controlled trial, 196 subjects received placebo or PM-HDM at 500, 1000, 3000, or 5000 mannan-conjugated therapeutic units (mTU)/mL in 9-arm groups for 4 months. All subjects received 5 SC doses (0.5 ml each) every 30 days plus 0.2 ml SL daily. The primary efficacy outcome was the improvement of titrated nasal provocation tests (NPT) with D. pteronyssinus at baseline and at the end of the study. All adverse events and reactions were recorded and assessed. Secondary outcomes were the combination of symptom and medication scores (CSMS) and serological markers. RESULTS: No moderate or severe adverse reactions were reported. Subjects improving the NPT after treatment ranged from 45% to 62% in active SC, 44% to 61% in active SL and 16% in placebo groups. Statistical differences between placebo and active groups were all significant above 500 mTU, being the highest with 3000 mTU SL (p = 0.004) and 5000 mTU SC (p = 0.011). CSMS improvement over placebo reached 70% (p < 0.001) in active 3000 mTU SC and 40% (p = 0.015) in 5000 mTU SL groups. CONCLUSIONS: PM-HDM immunotherapy was safe and successful in achieving primary and secondary clinical outcomes in SC and SL at either 3000 or 5000 mTU/ml.

Trained immunity induction by the inactivated mucosal vaccine MV130 protects against experimental viral respiratory infections.

MV130 is an inactivated polybacterial mucosal vaccine that confers protection to patients against recurrent respiratory infections, including those of viral etiology. However, its mechanism of action remains poorly understood. Here, we find that intranasal prophylaxis with MV130 modulates the lung immune landscape and provides long-term heterologous protection against viral respiratory infections in mice. Intranasal administration of MV130 provides protection against systemic candidiasis in wild-type and Rag1-deficient mice lacking functional lymphocytes, indicative of innate immune-mediated protection. Moreover, pharmacological inhibition of trained immunity with metformin abrogates the protection conferred by MV130 against influenza A virus respiratory infection. MV130 induces reprogramming of both mouse bone marrow progenitor cells and in vitro human monocytes, promoting an enhanced cytokine production that relies on a metabolic shift. Our results unveil that the mucosal administration of a fully inactivated bacterial vaccine provides protection against viral infections by a mechanism associated with the induction of trained immunity.

Sublingual MV140 for Prevention of Recurrent Urinary Tract Infections.

BACKGROUND: Recurrent urinary tract infections (UTIs), which consist of three or more episodes in 1 year or two or more infections in 6 months, affect 5% to 10% of women. MV140, a sublingual preparation of whole-cell inactivated bacteria, has shown clinical benefit in observational studies. This trial examined treatment with MV140 to prevent recurrent UTI. METHODS: In this multicenter, randomized, double-blind, placebo-controlled, parallel-group 1-year trial, 240 women 18 to 75 years of age from Spain and the United Kingdom with recurrent UTI were allocated to receive MV140 for 3 or 6 months or placebo for 6 months in a 1:1:1 ratio. The primary end point was the number of UTIs in the 9-month study period after 3 months of intervention. Key secondary end points were the percentage of women who were UTI free over the above period, time to UTI onset, and health-related quality of life. RESULTS: The median (interquartile range) of UTI episodes was 3.0 (0.5 to 6.0) for placebo compared with 0.0 (0.0 to 1.0) in both groups receiving MV140 (P<0.001). Among women treated with placebo, 25% (95% confidence interval [CI], 15% to 35%) were free of UTIs compared with 56% (95% CI, 44% to 67%) and 58% (95% CI, 44% to 67%) of women who received 3 and 6 months of MV140 treatment, respectively. A total of 205 AEs in 101 participants were registered (81, 76, and 48 in the placebo, 3-month MV140, and 6-month MV140 groups, respectively). CONCLUSIONS: In this controlled trial of modest size and duration, MV140 showed promising clinical efficacy in reducing recurrent UTI in women suffering from this condition. Adverse effects were not clinically limiting. (Funded by Inmunotek S.L. and Syner-Med [Pharmaceutical Products] Ltd.; ClinicalTrials.gov number, NCT02543827.)

Bacterial Mucosal Immunotherapy with MV130 Prevents Recurrent Wheezing in Children: A Randomized, Double-Blind, Placebo-controlled Clinical Trial.

Rationale: Recurrent wheezing in children represents a severe public health concern. Wheezing attacks (WA), mainly associated with viral infections, lack effective preventive therapies. Objectives: To evaluate the efficacy and safety of mucosal sublingual immunotherapy based on whole inactivated bacteria (MV130) in preventing WA in children. Methods: A Phase 3 randomized, double-blind, placebo-controlled, parallel-group trial including a cohort of 120 children <3 years old with ⩾3 WA during the previous year was conducted. Children with a positive skin test to common aeroallergens in the area where the clinical trial was performed were excluded from the trial. Subjects received MV130 or placebo daily for 6 months. The primary endpoint was the number of WA within 1 year after the first dose comparing MV130 and placebo. Measurements and Main Results: There was a significant lower number of WA in MV130 versus the placebo group, 3.0 (interquartile range [IQR], 2.0-4.0) versus 5.0 (IQR, 3.0-7.0) (P < 0.001). As secondary outcomes, a decrease in the duration of WA and a reduction in symptoms and medication scores in the MV130 versus placebo group were found. No adverse events were reported related to the active treatment. Conclusions: Mucosal bacterial immunotherapy with MV130 shows safety and clinical efficacy against recurrent WA in children.Clinical trial registered with www.clinicaltrials.gov (NCT01734811).

A pilot study of immunotherapy in dogs with atopic dermatitis using a mannan-Dermatophagoides farinae allergoid targeting dendritic cells.

BACKGROUND: Polymerized allergoids coupled to nonoxidized mannan (PM-allergoids) are novel allergen preparations used for immunotherapy. OBJECTIVE: To evaluate PM-allergoids as an alternative immunotherapy for dogs with canine atopic dermatitis (cAD) associated with serological responses to Dermatophagoides farinae allergens. ANIMALS: Sixteen dogs with history and clinical signs of cAD; positive on serum allergen specific IgE testing to D. farinae. Twelve dogs were, in addition, positive to Acarus siro and/or Lepidoglyphus destructor. METHODS AND MATERIALS: A prospective pilot study with no control group. PM-allergoids were administered by subcutaneous injection over a 10 month period. A pruritus Visual Analog Scale (pVAS) and medication scores were evaluated. Adverse reactions were recorded. RESULTS: The median value of the pVAS of the dogs decreased from 0.6 to 0.2 with a median of 67% improvement over the first three months (P < 0.0001). The individual improvement for each dog was greater than 60%. No major adverse effects were observed. CONCLUSIONS AND CLINICAL IMPORTANCE: Allergen-specific immunotherapy using an allergoid coupled to nonoxidized mannan may be an effective alternative for the management of cAD.

Mite allergoids coupled to nonoxidized mannan from Saccharomyces cerevisae efficiently target canine dendritic cells for novel allergy immunotherapy in veterinary medicine.

We have recently reported that grass pollen allergoids conjugated with nonoxidized mannan of Saccharomyces cerevisae using glutaraldehyde results in a novel hypoallergenic mannan-allergen complex with improved properties for allergen vaccination. Using this approach, human dendritic cells show a better allergen uptake and cytokine profile production (higher IL-10/IL-4 ratio) for therapeutic purposes. Here we aim to address whether a similar approach can be extended to dogs using canine dendritic cells. Six healthy Spanish Greyhound dogs were used as blood donors to obtain canine dendritic cells (DC) derived from peripheral blood monocytes. Allergens from Dermatophagoides farinae mite were polymerized and conjugated with nonoxidized mannan. Nuclear magnetic resonance (NMR), gel electrophoresis (SDS-PAGE), immunoblotting and IgE-ELISA inhibition studies were conducted to evaluate the main characteristics of the allergoid obtained. Mannan-allergen conjugate and controls were assayed in vitro for canine DC uptake and production of IL-4 and IL-10. The results indicate that the conjugation of D. farinae allergens with nonoxidized mannan was feasible using glutaraldehyde. The resulting product was a polymerized structure showing a high molecular weight as detected by NMR and SDS-PAGE analysis. The mannan-allergen conjugate was hypoallergenic with a reduced reactivity with specific dog IgE. An increase in both allergen uptake and IL-10/IL-4 ratio was obtained when canine DCs were incubated with the mannan-allergen conjugate, as compared with the control allergen preparations (unmodified D. farinae allergens and oxidized mannan-allergen conjugate). We conclude that hypoallergenic D. farinae allergens coupled to nonoxidized mannan is a novel allergen preparation suitable for canine allergy immunotherapy targeting dendritic cells.

Novel vaccines targeting dendritic cells by coupling allergoids to nonoxidized mannan enhance allergen uptake and induce functional regulatory T cells through programmed death ligand 1.

BACKGROUND: Allergen immunotherapy (AIT) is the only curative treatment for allergy. AIT faces pitfalls related to efficacy, security, duration, and patient compliance. Novel vaccines overcoming such inconveniences are in demand. OBJECTIVES: We sought to study the immunologic mechanisms of action for novel vaccines targeting dendritic cells (DCs) generated by coupling glutaraldehyde-polymerized grass pollen allergoids to nonoxidized mannan (PM) compared with glutaraldehyde-polymerized allergoids (P) or native grass pollen extracts (N). METHODS: Skin prick tests and basophil activation tests with N, P, or PM were performed in patients with grass pollen allergy. IgE-blocking experiments, flow cytometry, confocal microscopy, cocultures, suppression assays, real-time quantitative PCR, ELISAs, and ELISpot assays were performed to assess allergen capture by human DCs and T-cell responses. BALB/c mice were immunized with PM, N, or P. Antibody levels, cytokine production by splenocytes, and splenic forkhead box P3 (FOXP3)(+) regulatory T (Treg) cells were quantified. Experiments with oxidized PM were also performed. RESULTS: PM displays in vivo hypoallergenicity, induces potent blocking antibodies, and is captured by human DCs much more efficiently than N or P by mechanisms depending on mannose receptor- and dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin-mediated internalization. PM endorses human DCs to generate functional FOXP3(+) Treg cells through programmed death ligand 1. Immunization of mice with PM induces a shift to nonallergic responses and increases the frequency of splenic FOXP3(+) Treg cells. Mild oxidation impairs these effects in human subjects and mice, demonstrating the essential role of preserving the carbohydrate structure of mannan. CONCLUSIONS: Allergoids conjugated to nonoxidized mannan represent suitable vaccines for AIT. Our findings might also be of the utmost relevance to development of therapeutic interventions in other immune tolerance-related diseases.

Structural studies of novel glycoconjugates from polymerized allergens (allergoids) and mannans as allergy vaccines.

Immunotherapy for treating IgE-mediated allergies requires high doses of the corresponding allergen. This may result in undesired side effects and, to avoid them, hypoallergenic allergens (allergoids) polymerized with glutaraldehyde are commonly used. Targeting allergoids to dendritic cells to enhance cell uptake may result in a more effective immunotherapy. Allergoids coupled to yeast mannan, as source of polymannoses, would be suitable for this purpose, since mannose-binding receptors are expressed on these cells. Conventional conjugation procedures of mannan to proteins use oxidized mannan to release reactive aldehydes able to bind to free amino groups in the protein; yet, allergoids lack these latter because their previous treatment with glutaraldehyde. The aim of this study was to obtain allergoids conjugated to mannan by an alternative approach based on just glutaraldehyde treatment, taking advantage of the mannoprotein bound to the polymannose backbone. Allergoid-mannan glycoconjugates were produced in a single step by treating with glutaraldehyde a defined mixture of allergens derived from Phleum pratense grass pollen and native mannan (non-oxidized) from Saccharomyces cerevisae. Analytical and structural studies, including 2D-DOSY and (1)H-(13)C HSQC nuclear magnetic resonance spectra, demonstrated the feasibility of such an approach. The glycoconjugates obtained were polymers of high molecular weight showing a higher stability than the native allergen or the conventional allergoid without mannan. The allergoid-mannan glycoconjugates were hypoallergenic as detected by the IgE reactivity with sera from grass allergic patients, even with lower reactivity than conventional allergoid without mannan. Thus, stable hypoallergenic allergoids conjugated to mannan suitable for using in immunotherapy can be achieved using glutaraldehyde. In contrast to mannan oxidation, the glutaraldehyde approach allows to preserve mannoses with their native geometry, which may be functionally important for its receptor-mediated recognition.

Comparison of the allergenicity and Ole e 1 content of 6 varieties of Olea europaea pollen collected during 5 consecutive years.

BACKGROUND: Numerous varieties of Olea europaea have been described in Mediterranean countries. OBJECTIVE: To investigate the immunochemical characteristics of 6 varieties of Olea europaea collected during 5 consecutive years. METHODS: The varieties Carrasquefio, Manzanillo, Acebuche (wild olive), Hojiblanco, Picual, and Nevado were analyzed. Pollen samples from each variety were collected for 5 consecutive years from the same cultivars by trained personnel. The antigenic and allergenic profiles of these extracts were evaluated by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot using the serum of 29 O. europaea-allergic individuals. Ole e 1 was measured using enzyme-linked immunosorbent assay and purified Ole e 1 and rabbit polyclonal antibodies. Allergenic potency was determined using enzyme-linked immunosorbent assay inhibition and is expressed in histamine equivalent prick units per gram of raw material. RESULTS: Hojiblanco and Acebuche had the lowest mean +/- SD Ole e 1 content in the 5 years (0.045 +/- 0.029 and 0.059 +/-0.031 microg/microg of freeze-dried material, respectively). The variety with the highest mean +/- SD Ole e 1 content was Picual (0.19 +/-0.075 microg/microg). Hojiblanco had the lowest total biological potency throughout the study. A positive correlation was obtained between rainfall in the winter months and total allergenicity of the 6 varieties. CONCLUSIONS: The different varieties of O. europaea pollen demonstrated great differences in allergenic potency and Ole e 1 content. These differences were maintained throughout the study, suggesting that they are due to genetic differences intrinsic to the varieties, although certain climatic effects may also play a role.

Successful management of mite-allergic asthma with modified extracts of Dermatophagoides pteronyssinus and Dermatophagoides farinae in a double-blind, placebo-controlled study.

BACKGROUND: Mite sensitivity is highly prevalent in tropical and subtropical regions, such as the Canary Islands. OBJECTIVES: To evaluate the clinical efficacy and safety of a depigmented polymerized allergen vaccine containing a 50% mixture of Dermatophagoides pteronyssinus and Dermatophagoides farinae. METHODS: Sixty-four patients participated in the study. It was prospective, double-blind, and placebo-controlled, with random allocation of patients to receive active treatment or placebo. The active group received a mixture of modified allergen extracts containing 50% D pteronyssinus and 50% D farinae; the control group received placebo. All individuals were diagnosed with mild/moderate asthma and rhinoconjunctivitis caused by sensitization to D pteronyssinus and D farinae. Bronchial provocation test (BPT) was considered the main outcome to document clinical efficacy. RESULTS: Fifty-four patients completed the study. The active group experienced a significant improvement in BPT (P < .001), whereas the placebo group did not (P = .648). At the end of the study, 20 patients in the active versus 9 in the placebo group (P = .013; odds ratio, 5.71 [1.76, 18.51]) needed more than twice the amount of allergen to obtain a positive BPT. The median improvement in the active group over placebo was 53.76% in total symptom and 58.09% in medication scores. CONCLUSION: Immunotherapy with a mixture of modified allergen extracts of D pteronyssinus and D farinae is safe and efficacious to treat mite-allergic asthma. CLINICAL IMPLICATIONS: This immunotherapy modifies the natural course of the illness because it improves all clinical outcomes measured and prevents the worsening of specific bronchial hyperreactivity.

Mite immunotherapy.

Dermatophagoides pteronyssinus and D. farinae are the most common house dust mites and are among the most common sources of indoor allergens worldwide. These species are very common in humid regions, where most allergic individuals are sensitized to house dust mites. Specific immunotherapy with mite extracts has demonstrated clinical benefits in several double-blind, placebo-controlled trials that are included in recent reviews of subcutaneous immunotherapy, including pediatric and adult patients with rhinoconjunctivitis and or asthma. Most successful studies of mite immunotherapy have used native allergen extracts adsorbed onto aluminum hydroxide, or chemically modified mite-allergen extracts. Several studies have also shown efficacy using sublingual immunotherapy in pediatric and adult patients with asthma and/or rhinitis. Additionally, the efficacy of subcutaneous immunotherapy has been demonstrated in patients with atopic dermatitis, although more double-blind, placebo-controlled studies are needed. Based on several studies, it cannot be concluded that mite immunotherapy is more dangerous or safer than immunotherapy with grasses, epithelia, or animal epithelia. Because the delivery of high doses of allergen carries with it the risk for immunoglobulin E (IgE)-mediated events, several methods have been developed to reduce specific IgE binding to mite-allergen extracts. An important challenge for future mite immunotherapy modalities is the delivery of relatively high doses without a significant risk for severe reactions.

Comparative study of tolerance between unmodified and high doses of chemically modified allergen vaccines of Dermatophagoides pteronyssinus.

BACKGROUND: The physiochemical modification of allergens to reduce allergenicity, while retaining immunogenicity, provides a chance for the administration of higher doses of immunotherapy, with a decreased risk of systemic reactions. OBJECTIVE: To evaluate the safety of doses of depigmented glutaraldehyde-polymerized vaccine of Dermatophagoides pteronyssinus increasing those used in normal clinical conditions in comparison with regular doses of a non-modified vaccine. MATERIALS AND METHODS: The study was double-blind, parallel and included two patient groups. Twenty-three patients were treated weekly during 9 visits for the build-up phase, followed by 2-weekly maintenance doses (a total of 11 injections per patient). Eleven patients (mean age 22 years) received immunotherapy with the standardized modified vaccine. The maximum dose used was the result of depigmenting and polymerizing 100 times the maximum dose used with the native extract. The maximum concentration used was 990 mug/ml of freeze-dried material. Twelve patients (mean age 24 years) received a standardized, unmodified allergenic extract. The maximum concentration used was 70 mug of freeze-dried material/ml, with a potency of 10 HEP(L)/ml. The tolerance was evaluated recording all the side reactions related to immunotherapy and graded following the recommendations of the European Academy of Allergology and Clinical Immunology. RESULTS: In both groups, all immediate local reactions were clinically not relevant. Patients treated with the native extract experienced 42 local immediate and 24 delayed reactions (1 of them had a diameter >10 cm), whereas patients treated with the modified extract experienced 30 local immediate and 21 delayed reactions (2 of them had a diameter >10 cm). Four systemic reactions in 2 patients, 1 immediate of grade 1 and 3 delayed of grade 2 were reported in the group treated with native extract and 1 delayed of grade 2 in the group treated with the modified preparation. CONCLUSIONS: The modified extract of D. pteronyssinus, used at concentrations which are 10 times higher than those regularly administered in clinical practice, demonstrated to be safe to treat D. pteronyssinus-sensitive patients. The majority of the local reactions (immediate and delayed) were clinically not relevant (diameter <5 cm). No systemic reactions of grade 3 or 4 were noted.